Method of Scientific Investigation
Scientific investigation method
- A scientific method is a series of systematic steps which a scientist practises when conducting an investigation.
- The steps of a scientific investigation are as follows:
- Identifying the problem
- Identifying the variables
- Making a hypothesis
- Planning the investigation
- Carrying out the experiment
- Collecting and recording data
- Analysing and interpreting data
- Making a conclusion
- Writing a report
- Making a hypothesis
- Making hypothesis is the process of forming a general statement about the relationship between the variable that is manipulated and the responding variable.
- a hypothesis is also a statement of a scientific concept or principle made as a solution to the problem.
- Planning investigation
- then planning of an investigation often involves the following:
- determining the apparatus and materials
- determining the procedures
- determining the observation to be made and measurements
- determining the correct and safe techniques
- determining the set of apparatus of control experiments
- identifying the variables
- Carrying out the investigation
- the apparatus, materials and procedures must be handled correctly and safely when carrying out investigations.
- The variebles must be determined accurately
- The observations must be made accurately and objectively.
- Collecting and recording data
- Data collected by measurement in digits are called quantitative data.
- Data collected by more observation and do not involve accurate measurements are known as qualitative data.An assessment of the characteristics of an observation is also part of the qualitative data.
- The data collected can be recorded in the form of:
- Pie chart
- Bar chart
- Analysing and interpreting data
- Analysing and interpreting data
- Making a conclusion
- Writing a report
The scientific attitudes and noble values ned to be practised when conducting a scientific investigation to ensure a better understanding and interpretation of a scientific investigation.A scientist must have scientific attitudes and noble values such asa being curious in stating a problem statement, being honest and accurate in recordibg and validating data, being responsible for the safety of oneself, others and the environment when conducting an experiment, being critical and analytical thinking when proposing a hypothesis and being objective when making a conclusion.
- Body coordination is a life process that involves harmonious fuctioning of interrelated organs and parts in the body to produce a coordinated response
- Two body systems that control and regulate coordination are:
- The nervous system
- The endocrine system
- A stimulus is a detectable change in the internal or external environment.It evokes a response.
- Response is an action or movement as a result of a stimulus.
- The nervous system handles fast and short responses which involve the transmission of electrical impulses
- The human nervous system can be divided into:
- The central nervous system (CNS) which consists of the brain and spinal cord.
- The peripheral nervous system (PNS) which consists of cranial nerves and spinal nerves.
- A neurone is a nerve cell which is the basic functional unit of the nervous system
- The central nernous system consists of the brain and spinal cord
- The peripheral nervous system consists of cranial nerves and spinal nerves.
- The brain is an organ that is the centre of control and coordination in the nervous system
- The spinal cord controls reflex action
- The peripheral nervous system is the network of nerves which connect the central nervous system with other parts of the body.
- Cranial nerves composed of 12 pairs of nerves which orogonate from the brain and are connected to sense organs in the head and neck, and also to effectors such as the muscles or glands in the body cavity.
- Spinal nerves are composed of 31 pairs of nerves which originate from spinal cord and are connected to sense organs and effectors in the whole body including hands and legs.
- A neurone is a nerve cell.It is the basic functional unit of the nervous system
- The cell body contains many projections
- Dendrons - projections from the cytoplasm that point outward from the cell body
- Dendrites - smaller projections that branch from dendrons or axons
- Axons - another type of projection
- Dendrans and dendrites receive messages from other cells and trnasmit the message to the cell body
- Axons conduct messages away from the cell body
- Some axons in certain neurones are covered by myelin sheath.The sheath breaks up at intervals along the dendrons or axons.This enables impulses to jump from one node to another, shortening the time impulses travel along the surface of the axons or dendrons.
- Besides this, the meylin sheath is important because:
- It acts as an electrical insulator
- it is a source of food for axons and dendrons
- it also protects axons and dendrons from physical injury.
- There are three types of neurones
- sensory neurones
- motor neurones
- interneurones (relay neurones)
Receptors and effectors
- Any changes which occur inside and outside of the human body are known as stimuli
- Receptors are sensory cells that detect and receive stimuli and turn them into electrical impulses
- Effectors are muscles or glands which produce responses due to stimuli.They respond to stimuli by:
- gland secretion
- Figure above shows how the human nervous system works.
- are messages conveyed along the nerve in the form of weak electrical pulse
- An impulse moves only in one direction as shown in figure.
Impulses move in one direction
- A reflex action is a rapid,automatic unlearned response to a stimulus.This action is involuntary and cannot be controlled by the brain
- A reflex action does not require conscious thought or decision by the brain
- The components involved in a reflex action are:
- The receptors
- The effectors
- Sensory neurones
- Relay neurones
- Motor neurones
- A reflex arc is a sequence of pathways taken by the impulses from receptors to effectors in a reflex action
- The pathway of impulses in a reflex arc are as follow:
Pathway of impulses
- Proprioceptors are sense organs which are connected to sensory neurones.Humans are able to determine the position of their legs, arms, head and other parts, along with the orientation of the body as a whole with this type of receptors
- Proprioceptors are found in all skeletal muscles, tendons, ligaments and joints.They provide information to the brain regarding adjustment in posture and movement.Therefore, adjusments may be made to maintain body posture or to carry out a particular body movement.
- Kinaesthesis is the ability to sense the position, location, orientation and movement of the body and its part without looking at ourselves.
The Human Brain and Its Complexity
Structure of the brain
- The human brain is the most complex organs in the human body.It is also the most complex brain among all mammals.
- The brain is the centre that contols and coordinates our responses as shown in above
- The human brain has an external layer which is white in colour.
- The grey-coloured layer is made up of closely packed neurone cell bodies which form the grey matter of the brain
- The white-coloured layer is made up of nerve fibres which form the white matter of the brain
- The human brain can be divided into three main parts:
- Medulla oblongata
- The cerebrum is the largest part of the human brain.It makes up about 80% of the mass of the human brain.
- The cerebrum can be divided into two hemispheres.
- Right hemisphere
- Left hemisphere
- Nerve impulses from the left side of the body will be received by the right hemisphere whereas nerve impulses from the right side of the body will be received by the left hemisphere
- Functions of the cerebrum are:
- It controls voluntary and highest intellectual functions such as thinking, learning and problem solving.
- It regulates emotion and memory through the limbic system.
- It controls human behavior.
- Receives and interpets impulses from sensory organs
- The cerebellum is located below and behind the cerebrum
- The function of the cerebellum are:
- Controlling and maintaining posture and balance of the body
- Controlling and coordinating muscular activities
- Medulla oblongata is the lower most portion of the brain and is continuos with the spinal cord.It is the smallest component of the brain
- Medulla oblongata relays nerve signals between the brain and spinal cord.
- Medulla oblongata controlsn automatic functions
- Human respond to a stimulus through voluntary actions and involuntary actions
Effect of injuries to specific parts of the human brain
Hormonal Coordination in the Body
- are chemicals secreted by endocrine glands.Hormone produced are secreted directly into the bloodstream and carried by blood to tissues or organs without the need of any ducts.They are usually secreted is small amounts
- The hormones have a specific effect only on the tissue or an organ designed to receive its message .This tissue or organ is called target tissueor target organ.This is because only this specifictissue or organ will respond to them.
- Important roles of hormones are:
- causing physical and physiological changes.
- Controlling the rate of body process
- Influencing growth
- Chemical coordination involves the endocrine glands and their secretion
- Endocrine system consists of endocrine glands and their secretion
- Endocrine glands do not have ducts.Thus it is also called ductless glands.
- is located at the base of the brain just beneath the hypothalamus
- The anterior lobe regulates the activity of several glands.Among these are thyroid,adrenals and reproductive glands.
- It produces hormones such as:
- Corticotropin - stimulates the adrenal gland to produce certain hormones.
- Growth hormone - stimulates the growth of bones, muscles and other body organs.Plays a role in the handling of nutriens and minerals in the human body.
- Prolactin - promotes the development of glandular tissue in the female breast during pregnancy.Stimulates milk production in women who are breastfeeding.
- Thyrotropin - stimulates the thyroid gland to produce thyroxine hormones.
- The posterior lobe of the pituitary gland releases antidiuretic hormones (ADH).This hormone acts on the kidneys to regulate water content and write output.Oxytocin is also released by the posterior lobe.Oxytocin triggers the contraction of the uterus during labour.It also stimulates the ejection of milk from the lactating breast.
- The thyroid gland is located in the front of the lower neck.
- Hormone thyroxine produced by the thyroid gland has the following functions:
- Controls metabolic rate
- Controls skeletal growth
- Controls mental development
- Insulin - insulin decreases blood glucose concentration by stimulating the conversion of glucose into glycogen in the liver.
- Glucagon - glucagon increases blood glucose concentration by stimulating the conversion of glycogen to glucose in the liver.
- is located on top of each kidney.
- The adrenal glands have two parts; the internal part is the adrenal cortex and the inner part is name adrenal medulla
- Adrenal cortex produces hormones called corticosteroids.Corticosteroids influence or regulate salt and water balance in the body, the body's response to stress,metanolism,the immune system and sexual development abd function.
- Adrenal medulla produces catecholamines such as adrenaline.
- are located in the female reproductive system
- Ovaries produce two groups of female sex hormones.
- Oestrogen is involved in the development of secondary sexual characteristics in female such as:
- The development of breasts
- The accumulation of body fat aroundthe hips and thighs.
- Maturation of reproductive organs such as the uterus and vagina.
- Progesterone prepare the uterus lining for pregnancy
- is located in the male reproductives system
- testis secretes hormones called androgens
- The most important androgen hormone is testosterone.
Coordination between the Nervous System and the Endocrine System
- The two types of coordination work together at certain times.The human digestive system is a good example.When food is served,the mouth will start to salivate and this response is coordinated by the nervous system.Gastrin a type of hormone is secreted when the half-digested food goes into the stomach.Gastrin causes the stomach wall to produce hydrochloric acid and other emzymes to carry out further digestion.
Effects of Drug Abuse on Body Coordination and Health
Definition of drugs
- Drugs are chemical or biological substances which affect the function of the nerveous system,especially the brain,causing changes in behaviour and personality.They change the way the body works.
- The four main types of drugs are:
- is the misuse or overuse of any medication or drug
- Reasons of drug abuse include:
- use drugs because they are thrill-seekers
- use drugs out of curiosity or because their friends do it
- use drugs in order to cope with unpleasant emotions and difficulties in life
Effects of Excessive Consumption of Alcohol on Body Coordination and Health
- Ethanol commonly known as alcohol is found in most alcoholic drinks.It is a strong psychoactive substance with a depressing effect.
- Ethanol is produced in a process call fermentation.Fermantation is a process that uses yeast or bacteria to change the glucose in the food into ethanol.
Effect of excessive consumption of alcohol on body coordination
- Alcohol is a depressant.This means it slows down the function of the central nervous system.
- When alcohol is consumed, it is absorbed into the bloodstream rapidly and travels around the body to the brain.
- Alcohol is broken down into acetaldehyde by the enzyme, alcohol dehydrogenase in the liver.The acetaldehyde is then broken down into acetic acid by the enzyme acetaldehyde dehydrogenase.Next acetic acid is converted into fats or carbon dioxide and water.Fatty acids build up as plaques in the capillaries around liver cells.Liver cells begin to die.This leads to the liver disease called cirrhosis.As we know the liver is damaged,certain toxins build up.This leads to sympthoms of jaundice.
- Foetal alcohol syndrome is another one consequence of excessive consumption of alcohol use.
- Foetal alcohol syndrome:
- a foetus is fed through the placenta inside the mother.Since alcohol passes easily through the placenta,the developing foetus gets a dose of alcohol when the mother drinks alcohol.
UNDERSTANDING PROCESS CELL DIVISION
- We know that our bodies built from millions Tues In this cell there is a center of activity known as the nucleus. There are chromosomes in the nucleus that contains genes. Gen, this is the nature of our control. For example it controls whether our hair curly or not.
- Genes are genes that carry material genetic information.
- Gene located in chromosome. If viewed through a microscope, chromosomes are structures in the nucleus stranded Tues
- Humans can grow and reproduce because the cell can divide. Two types of cell division is Mitosis and Meiosis. Mitosis occurs in the entire body and cause each day we grow. The number of chromosomes that results remain the same as the original genes [sometimes called the 'master gene']. Meiosis also occurs in the testes or ovaries to produce sperm or ovum. Number of chromosomes in sperm is half the number of cells holding. Human chromosome 23 has a half from Stem cell chromosomes (46 chromosomes).
- There are many differences between Mitosis and Meiosis
- Scientists already know that organisms typically have a pair of chromosomes that carry a pair of genes. Genes may be different or the same. There are two types of genes and gene dominant gene resesif.
- Gene dominant gene is a strong and able to highlight features in the organism. Resesif genes are genes that weak. It can not be met if the features highlight a dominant gene. Gen.
- resesif can only highlight the features if he came to the same pair resesif genes.Dominant gene will result in a dominant nature. Based on several examples of genetic research scientist dominant nature of human nature is such as wavy hair and the ability to roll tongue. [the ability to roll his tongue].Resesif properties are properties such as hair is straight and can not roll tongue. How these properties can be handed down from parents to children?.
- Human cell has 46 chromosomes (23 pairs of genes). Sperm and ovum that results from Meiosis only contain only 23 chromosomes. If the sperm carrying genes that control the nature of curly hair (dominant) ovum mix that brings nature hair straight, then the resulting child will be curly-haired.
- Chromosome structure in gamet:
- Chromosomes X and Y chromosome known as the "sex chromosome". This chromosome determines gender of a person.
SEX DETERMINATION AND THE OCCURRENCE OF TWINS
- 22 pairs of choromosomes are known as autosomes.The largest of the autosomes is referred to as chromosome 1,the next largest as chromosomes 2, and so on, down to the smallest autosomes , which are chromosomes 21 and 22.The 23rd pair of the last two chromosomes are known as sex chromosomes.Sex choromosomes are responsible for determining gender.There are two types of sex chromosomes:
- X chromosomes
- Y chromosomes
- The human male will have a genetic make up of pairs of autosomes and two types of sex choromosomes X and Y
- The human female will have a genetic make up of 22 pairs of autosomes and only one type of sex chromosomes, XX.
Formation of twins
- Under normal circumstances, one ovum is released in one menstrual cycle.During fertilision, one ovum will be fertilised by one sperm to produce one zygote.Therefore, a single baby will be born,
- There are two types of twins:
- Non- identical twins
- Identical twins
- More than one ovum is produced in expectional cases.Each ovum will be fertilised by different sperms, developing into zygotes
Formation of non-identical twins
- Sometimes, one ovum is fertilised and then divides immediately into two or more zygotes through division, resulting in twins.
- The zygotes then develop into two embryos.Both embryos share one placenta with separate amniotic sacs.Babies born in this wy are known as identical twins
- In certain cases identical twins are born joined at identical sides.This happens because the zygote failed to divide completely into two separate embryos.
- definition of mutation - Human traits can be altered by sudden changes in chromosomes or genes.This is known as mutation
- Mutation can happen in somatic or reproductive cells.The difference is mutation in somatic cells cannot be inherited by the next generation.
- Mutation that happens in either the sperm or ovum may be inherited by the next generation although the parents do not possess these traits.
- Chromosome mutation occurs when changes take place in the structure of the chromosome or to the number of choromosomes.
- Gene mutation occurs when there is a change in the chemocal structure of a gene.
- Klinefelter's syndrome
Karyotype of an individual with Klinefelter's syndrome
- turner's syndrome
Karyotype of an individual with turner's syndrome
- down's syndrome
Non-disjunction in meiosis I and meiosis II
- is a condition where there is an absence of the melanin pigment in the skin, hair and iris in human.This condition is caused by a recessive gene taht affects the production of melanin.
- Colour blindness is a condition that arises from the mutation of the gene for colour vision.This causes a person to be unable to differentiate between the colour green and red.The mutation produces a recessive gene.
- is a disease where the blood fails to clot.As a result severe sufferers can bleed to death without treatment .Even if with treatment, internal bleeding in the joints is the most problematic complication since it leads to paintful arthritis.This disease is an example of a sex-linked disease which is caused by a recessive allele on the X chromosome.
Haemophoilia man married to a normal female
A normal man married to a carrier female
Causes of mutation
- Some mutations are induced and others are spontaneous.
- Mutation is more likely to occur as a result of exposure to mutagens.Mutagens are factors that cause mutation.Among the known mutgens are nuclear radiations,harmful rays and certain chemicals called carcinogens.
- Nuclear radiations will penetrate the nucleus of the cell and change the structure of the genes and chromosomes in the nucleus.
- Harmful rays are also mutagens
- Chemical - There are many hundreds of known chemical mutagens such as benzene,fungicides,herbicides,insecticides,pesticides and dioxins
Advantages and disadvantages of mutation
Advantages of mutation
- mutation is one of the sources for the creation of new species.
- mutation may lead to variation .Variation is the difference in traits between individual of the same species.
- If no mutation occurs,evolution could not have taken place.In other words mutation is a precursor of the evolution process.
- The disadvantages of mutation to humans can be grouped into:
- Physical deformities - is a type of physical deformity as a result of mutation.Suffers have extra fingers or toes on both hands or feet.
- Genetic diseases - Gene mutation many cause genetic diseases such as colour-blindness and albanism.
Effects of Genetic Research on Human Life
Distributions of gebe
- Amniocentesis is a test perfomed between 16 and 18 weeks of a woman's pregnancy.The drawn fluid is then analysed.This fluid can be tested not only to check for genetic problems but also to determine the sex of an unborn baby.
- In gene therapy, a detective gene in unhealthy cells will be replaced with a new and healthy gene by using a type of virus called retrovirus.
- Selective breeding is a technique which involves the choosing and breeding of animals or plants with desirable traits to ensure that these traits are inherited by the next generation.
- Oil palm is the highest yielding oil crop.Selective breeding between the oil palm species Pisifera and Dura to produce a new species called Tenera is a good example.This is shown in Figure 3.32.The oil palm is continually being improved through breeding.
- Table shows comparison between Pisifera, Dura and Tenera
- Vaccines and better medicines are produced in medicine and healthcare through genetic research.
- The quality of crops and livestock have been improved by genetic research.
- Crops can be affected by many different diseases.Transgenic plants which are resistant to certain diseases are produced to solve this problem
- Genetic research may lead to exitinction of species since new varieties replace them.
- Cloning oe genetic engineering, especially on human beings may give rise to moral,ethical and religious problems.
- Genetically modified food may be harmful to human health.
- Ecosystem can also be threatened by genetic technology.
Variation Among Living Things
Definition of variation
- Variation is the difference in trais of an organism of the same species which can be passed on from one generation to another.
- Human differ from each other in terms of
- Physical characteristics
- There are two types of variation
- Continuous variation - differences in traits which are not very distict or discrete.This type of variation tend to be quantitative. controlled by genetic factors and is often significantly affected by environmental influences.
- Discontinuous variation - is variation which deals with clear-cut differences in traits.Discontinuous variation is completely controlled by genetic factors and is not effected at all by environmental factors.
- There are two factors that lead to variation:
- Genetic factors
- variation that is controlled by genetic factors can be inherited.Crossing-over occurs at the start of Prophase I during meiosis.
- Chromosome separate randomly in gamete formation
- Random fertilisation
- Environmental factors
- environmental factors which cause variation include climate.light, moisture,oxygen,pressure,soil fertility,temperature,type of food and lifestyle.
- The emergence of traits which can adapt well to changes in the environment enables the organism to survive,breed and inherit new characteristics.
- Variation ensures the survival of a species.Variation may encourage the formation of new species,a process called speciation
- There will be no diversity in organisms without variation.
- Pedigree analysis is another term for the construction of a family tree.
- Pedigree analysis is a schematic chart that shows the flow of a certain trait from parents to the next generation and other related members in a family through inheritance.
- Table shows a a list of symbols commonly used in a human pedigree analysis.
- All things wheather living or non-living things in the world consist of matter.Matter is any living or non-living thing that has mass and occupies space.Matter is made up of tiny and discrete particles
- The kinetic Theory of Matter states that matter is mae up of tiny and discrete particles which are always moving in random motion
- Matter exists in three states which are solid,liquid and the gaseous states.
- All matter whether solid, liquid or in the gaseous state, have the following characteristics:
- Made up of tiny particles
- Particles always vibrate and are sometimes moving
- has space between the particles
- In the solid state, particules:
- are arranged in a regular pattern
- are tightly packed
- have fixed positions
- do not move freely
- only vibrate and rotate around their fixed positions.
- In the liquid state,particles:
- are not arranged in a regular pattern
- are further apart
- do not have fixed positions
- move freely around one another
- In the gaseous state,particles:
- are not arranged in a regular pattern
- are widely spaced
- do not have fixed positions
- process where solid changes to gas or gas to solid without going htrough the liquid
- e.g. iodine, dry ice, ammonium chloride and naphthalene
- can occur because particles move into the space in between the particles of solids, liquids and gases
- Eg: when 50 cm3 of ethanol and 50 cm3 of distilled water are mixed,only 98cm3 of mixture are obtained.This is because the ethanol and water particles occupy each other spaces between the particles.
- is random movement example shown by smoke particles or pollen grains when knocked about by air particles
Changes in the state of matter
Impurities like common salt can
- increase the boiling point of distilled water (102oc)
- lower the freezing point of distilled water (-2oc)
- all matter consists of tiny units called atoms
a neutral atom is the number of protons equal to the number of electron (Number of proton = number of electron)
Ion are atoms which have charge:
- Positive ion = atom which losses of electron
- Negative ion = atom which receives more electron
Proton number = numner of protons = number of electrons
Nucleon number = total number of protons and neutrons
Isotopes = atoms that posses the same number of proton but different number of neutrons
= same proton number (chemical properties) but different nucleon number (physical properties)
The periodic table is important in the systematic and methodical study of elements.
Classification of elements in periodic table are arranged orderly and systematically of increasing proton number from left to right based on the number of protons.
Characteristic or Properties of Metals and Non-Metals
- Distilled water is pure water because it does not contain any dissolve substance or forein matter.
- The boiling point of pure water is 100oc and melting point is 0oc
- However impurities such as salt can increase the boiling point to 102oc and lower the melting points to -3oc
- is the process of boiling the liquid and condensing the vapour into pure liquid
- Is forming of pure crystal from a hot saturated of a salt when it is cooled
- E.g mining salt from sea water
5.1 physical and chemical changes.
two types of changes involved in matter:
physical change are defined as the changes that only affect the physical properties of substances.
the characteristics of physical change are:
involves only physical changes such as shape or size of a substance.
involves changes in the state of matter;solid,liquid and gas.
chemicals composition and chemical properties of substances remain unchanged so that no new substances is formed.
less energy is needed.
the changes are reversible.
3.physical changes in our daily life are:
(a) *Melting of ice:
*Melting of chocolate.
(C) *Evaporation of water:
*evaporation of alcohol or evaporation of petrol.
(d)Natural water cycle.
(f)Dissolving salt and sugar in water.
(g)Formation of dew on the grass.
4.Physical changes being studied in a laboratary are:
Defined as the changes that affect the chemical composition and chemical properties of the substances.
the characteristics of chemical change are:
new substances known as products.
chemical composition and chemical properties of the new substances are different from the original substance which is known as reactant.
is usually fixed and irreversible.
needs large amount of energy.
3.chemical changes in our daily life are:
burning of paper or fossil fuels produces carbon dioxide and ash.
digestion of food.
washing dishes with detergent or washing hair using shampoo.
Change in colour of peeled apple when exposed to air.
decomposition of animal carcasses.
making bread from wheat flour.
4.examples of chemical changes being studied in a laboratary are:
Oxygen + glucose --------> carbon dioxide + water vapour + energy
Acid + alkali + -------> salt = water
electrolysis of water.
~COMPARING AND CONTRASTING PHYSICAL AND CHEMICAL CHANGES~
~5.2 HEAT CHANGE IN CHEMICAL REACTIONS~
CHEMICAL REACTION INVOLVES HEAT CHANGE
- chemical reactions involves changes in energy in the form of heat energy.
- chemical reactions,
energy is aborded to break bonds in the reactants.
energy is released when new bonds sre formed in the products.
-chemical reaction that absorbs energy is dissolving ammonium chloride in water.when ammonium chloride(Salt) is put into a beaker of water which is held with our hands,we can feel that the temperature of water falls.this is because the reaction in the beaker absorbs energy from the water and our hands.-Chemical reactions that releases energy is dissolving sodium hydroxide in water.When sodium hydroxide(SOAP) is put into a pail of water and stirred using our hands,we can feel that the soap solution becomes hot.this is because the reaction releases heat into the surroundings.
REACTION INVOLVING HEAT LOSS AND HEAT GAIN.
Chemical reactions can be classified into two groups:
exothermic reactions is defined as a reaction which releases energy in the form of heat into the surrounding (heat loss),and causes the surrounding temparature to increase.
the characteristics of exothermic reactions are:
heat is released into the surroundings.
Energy is released when bonds are formed because the energy needed to break the bond in the reactants is less than the energy released when new bonds are formed in the products.
surrounding temperature increases due to the release of energy but the temperature of mixture decreases.
Energy content of the reactant(s)
Higher energy content of the product(s)
1.~absorb energy or gain heat.
~surrounding temperature to decrease.
2.The characteristics of exothermic reaction are:
heat is absorbed.
Energy is aborded.
surrounding temperature decreases and temperature of the mixture increases.
energy content of the reactant(s) is lower than energy content of the product(s)
3.endothermic reactions are:
heating copper sulphate crystals.
dissolving ammonium chloride in water.
decomposition of mercury oxide by heat and decomposition of copper carbonate by heat.
HEAT CHANGES IN INDUSTRIAL CHEMICAL REACTIONS
ammonia is produced by the haber process on a large scale.
catalyst(iron)at atemparature of 450-500°C and a pressure of 200 atmospheres.
the process is reversible.
heat is released in the forward reaction (exothermic).
5.3 The reactivity of metals .
Activity a chemical reaction.
the reactions metals with water.
The reactivity of metals with water.
Highly reactive metals.
less reactive metals
The reactivity of metals with oxygen.
the metal oxide produced a different colour compared to the original metal as shown in table 5.6.
COMPARING AND CONTRASTING THE REACTIVITY OF METALS WITH WATER,ACIDS AND OXYGEN.
The reaction of metals with water,dilute acids and oxygen will individually produce different chemical substances.
table 5.8 shows the comparison of the reactivity of metals with water,dilute acids and oxygen:
Reactivity series of metals.
The reactivity series order of reactivity with oxygen
Table 5.9 shows the reactivity series of metals .
THE POSITION OF CARBON IN THE REACTIVITY SERIES OF METALS.
The raectivity series of metals shows the inclination of a metal to react with oxygen.
The operatinal definition of this experiment is carbon reduces a metal oxide to its metal if carbon is more reactive than the metal.
on the the other hand, carbon does not react with a metal oxide if it is less reactive than the metal.
5.4 APPLICATION OF THE REACTIVITY SERIES OF METALS
RELATING THE POSITION OF METALS IN THE REACTIVITY SERIES TO THE METHOD OF EXTRACTION OF METALS FROM THEIR ORES.
Table 5.12 shows some common ores.
Two methods of extraction of metals from their ores:
Electrolysis of the molten more.
reducation of metal ore using carbon
A Suitable method to extract a metal from its ore is based on the position of the metal in the reactivity series of metals as shown in table 5.13.
The importance of the reactivity series are:
Determine the method of extracting the metal.
Predict the reactivity of a particular metal.
Predict whether a particular metal can remove oxygen from another metal oxide.
The extraction of metals from their ores through reduction using carbon.
Metal which are located below carbon in the reactivity series are extracted through the reduction method by carbon.
Pure metals which can be extracted using carbon include tin,zinc,copper,iron and lead.
Tin extraction Process is carried out in two main stages as follows:
mixed with coke (carbon) and limestone (Calcium carbonate)
Decomposition of an electrolyte using electricity.
Electrical energy is changed into chemical energy.
electrolyte is a compound in molten form or aqueous solution which contains ions.
Positive ions (cations) and Negative ions (anions).
Electrical source is the source which generates electrical energy.
Ammeter measure the flow of current.
Electrolysis of an electrolyte using carbon electrodes.
Electrolysis process is based on the type of electrolyte decomposed and the movement of the ions.
Uses of electrolysis in industry
Extraction of metals
Purification of metals
Electroplating of metals
Extraction of metals
Extraction of metals.
Extraction of aluminium:
Mixed with cryolite
Purification of metals
Pure metal electrolysis.
Impure metal as the anode
Pure metal as the cathode
A salt solution as the electrolyte.
Electroplating of metals
Electroplating coating of a thin layer of less reactive metal on the surface of another more reactive metal electrolysis.
Electroplating a coin with copper.
Electroplating an iron nail with copper.
Electroplating costume jewellery with gold.
Tin plating to produce food cans
Electroplating iron nails with zinc.
Prevent a metal object from rusting.
Make metal look nicer,shiny and attractive.
5.6 The production of electrical energy from chemicals reactions
Chemical energy can change into electrical energy.
A simple cell is used hoe electrical energy id produced by chemical reaction.
Two different metal plates or carbon plate and a metal plate as electrodes.
A dilute acid,an alkali or a salt solution as an electrolyte.
The less reactive metal or carbon forms the positive electrode known as the anode
Various types of cells and their uses
Production of electrical energy from a simple cell to produce electrical energy.
5.7 Chemical reactions that occur in the presence of light.
Chemical reaction which require light.
Some reactions need light energy to start a chemical reaction.
Green plants synthesise food using chlorophyll pigment,light energy,water and carbon dioxide.
Hydrogen and oxygen as photolysis of water.
Food or glucose.
Effect of light on photosensitive chemicals
Is sensitive to Light is known as a photosensitive chemical.
Photosensitive chemical are:
- Silver chloride.
- silver bromide.
- Silver iodide.
- chlorine water.
- hypochlorite solution
- silver nitrate
5.8 Innovative efforts in the design of equipments using chemical reactions as sources of energy
using ellectrical energy efficiently.
6.1 Radioctive substances
Radioactive substances are:
Radioactive isotopes or radioisotopes.
Examples of radioisotopes:
Nuclei energy is produced.
Three types of radiations:
The uses of radioactive substances
6.2 Production of Nuclear Energy and Its Uses
Nuclear energy is released
Radio active decay and nuclear reaction
Two types of nuclear reactions:
An unstable nucleus is bombarded by high-speed neutrons,Form more stable nuclei.
Nuclear energy produced by nuclear fission is used to generate electricity.
Nucleus of uranium -235 is bombarded with high-speed neutrons.
Nucleus will absorb the neutron and split in two nuclei.
Two nuclei are radioactive barium-141 nucleus and krypton-92 nucleus.
Three new high-speed neutrons are produced.
a large amount of nuclear energy is released.
Two light nuclei combine to form a heavier nucleus.
Nuclear fusion of hydrogen isotopes:
Very high temperature and pressure,hydrogen-2 and hydrogen-3 isotopes fuse and form a helium nucleus.
Total mass after nuclear fusion is slightly lower than the mass before nuclear fusion.
Loss in mass is converted into large amount of nuclear energy and a neutron is released.
The uses of nuclear energy.
Used to propel vessels such as submarine and aircrafts which allow them to operate for one or two years without having to refuel.
Besides solar energy,Nuclear energy is the major source of energy that enables the satellites to operate for years.
Nuclear energy is mainly used to generate electricity.
Process of generating electricity from nuclear energy.
Uranium rods,Radioactive substances.
graphite rods,control the rate of chain reactions.
Heat energy ,boil water.
Steam rotates the turbine,produce electricity
The effect of nuclear energy production
6.3 The Need Proper Handling of Radioactive Substances
In 1986,a fire in a nuclear power plant in cherynobyl,Russia.This incident caused:
The death of thousands of people.
About 24 000 people will die of cancer in the next 70 years.
Farm and diary products in europe were polluted with radioactive substances .
The city was completely destroyed.
Proper safety measures should be taken when handling radioactive substances in order to prevent:
Nuclear disaster such as in chernobyl,Russia.
Health problem such as cancer.
genetic mutations .
Effect of radioactive radiations on living things can be categorised into short and long term as shown in table 6.3:
Correct ways of handling radioactive substances and radioactive wastes.
Symbol represent radioactive substances:
7.1 Formation of images by plane mirrors and lenses.
Formation of images by plane mirrors.
Distance image behind the screen same as the distances of the object.
Characteritics of images formed by convex and concave lenses.
A lens transparent material glass or plastic.
Table 7.4 shows the comparison of images formed by a convex and a concave lens .
A ray diagram shows the path of light rays passing through a lens.
A ray diagram is drawn using two rays from a point on the object as shown in table 7.5:
The ray diagram and the characteristic of images formed by convex lens is different according to the object distances as shown in table 7.6.
Focal length is defined as the distance between the focal point and the optical centre.
The symbol for local length is 'f '.
7.2 Formation of images by optical instruments
Identifying parts of optical instruments involved in image formation
Figure 7.5 Periscope
The same size as the object.
same object distance.
Two convex lenses.
Figure 7.6(a) Telescope
Figure 7.7(a)Magnifying glass.
Figure 7.8 Pinhole Camera
Real and inverted.
Size of the image dependent on the object distance in front of the pinhole camera.
Number of image dependent on the number of pinholes.
Nearby object,lens is adjusted away from the film.Distance between the lens and the film is increased.
Distant object,Lens is adjusted towards the film.The distance between the lens and film is decreased.
diaphragm control the amount of light entering the lens.Aperture focal length of the camera lens.
Table 7.9 shows effect of the light condition due to the size of the
diaphragm opening and the speed of the shutter opening.
Film capture the image of the object.
Real,inverted and smaller.
The human eye as an optical instrument.
Figure 7.10 structure of the human eye.
Image are formed here.It contains thousands of light sensitive cells which send nerve impulses when they receive light.
Carries nerve impulse to the brain to be processed.
The thickness of the lens can be altered to control the focus of the eye.
Light enters the eye through this opening,it appears black.
Helps to focus light onto the retina by refracting light rays that pass through it.
Control the size of the pupil.
Table 7.10 Function of main parts of the human eye.
Ability of the eye lens to change its focal length accommodation.
Radial muscles contract,circular muscles relax.
Size of the pupil bigger.
Radial muscles relax.
circular muscles contract.
Size of the pupil smaller.
Comparing the human eye with a camera.
The structure and function of various parts of human eye using the camera as an anology.
Table 7.12 shows the analogy between the structure and function of the eye and a camera.
7.3 Dispersion of light.
Dispersion of light.
Dispersion of light by a prism
Light dispersion light is split colour consituents Spectrum passes through a glass prism.
Red,Orange,yellow,green,blue,indigo and violet.
Formation of the rainbow
Dispersion of light.
7.4 Scattering of light.
Wavelength of the light.
Shorter more scattered.
Scattering of light in natural phenomena.
Short wavelength scattered more.
Eyes more sensitive to blue light.
At dawn or dusk:
Short wavelength scattered more..
Long wavelength Scattered less.
Sun reddish if polluted with dust.
7.5 Addition and substraction of coloured light.
Addition of coloured light.
Process two primary coloured lights overlap.
Subtraction of coloured lights by coloured filters.
Enables a particular coloured light to pass through it.
Red,green,and blue filters.
Allows lights of the same colours to pass.
Yellow,magenta and cyan filters.
allows lights of the same colours and primary colours that from them.
7.6 Using the principle of substraction of coloured lights to explain the appearance of coloured objects.
Primary coloured reflect its own colour.
Secondary coloured reflect its own colour and the colours that form it.
Table 7.16 shows the summary of the principle of subtraction of coloured lights in the appearance of an object.
Function of rod and cone cells in the eye.
Sensitive to low intensity light.
Sensitive to coloured light.
7.7 The Effects of Mixing Pigments.
Substract and reflects certain colours in light.
Living things such as plants and animals.
Uses of pigments.
Effects of mixing pigments.
Mixing of coloured pigment produces colours as shown in table 7.17.
Coloured lights reflected by different coloured pigments in white lights as shown in table 7.18.
Comparison between the coloured pigments and coloured light from different aspects as shown in table 7.19.
7.8 The importance of colour in daily life.
Symbols and signals.
Survival of living things.
Black ink to sharper clearer.
Brown for live wires.
Blue for neutral wires.
Yellow and green stripes for earth wires.
Symbols and signals.
Two white lines in the middle of the road indicate that no overtaking is permitted.
Yellow line painted side of the road ,Cars cannot be parked along the side of the road.
Yellow box painted with yellow stripes,Cannot stop inside the box.
Small red flag is raised when an event is being is being prepared,Small green flag is raised when the event is ready to begin.
Ambulance red light indicates an emergency.
7.9 Appreciating the benefits of various types of optical instruments of to mankind.
Table 7.20 shows optical instuments and their uses.
8.1 Properties of alloys and Their uses in industry.
Homogenuos mixture pure metal another pure metal or Non metal.
Alloying mixing other elements to the pure metal.
Alloying process is carried out as follow:
- A pure metal is melted
- some metal and non-metal are then added to the molten metal
- The mixture is the cooled
Alloying Changes the properties of metals.
Weakness and structure of a pure metal are improved by alloying.
Pure metals become more resistant to corrosion,shinier,more attractive appearance and harder.
Prevents corrosion of metals.
Improves the appearance of metals.
Copper has dull brown surface after being oxidised.
Alloying prevents rust,most alloys,nice shiny surface.
A little nickel is added to copper to produce copper nickel alloy.
Increases the hardness and strength of metals.
Metal such as magnesium,aluminium are soft and light.
Problem can overcome by alloying.Alloys are harder and stronger.
Magnesium is mixed with aluminium to produce magnalium.Magnalium is an alloys are hard but it still retains the lightness of both these pure metals.
Arrangement of particles in alloys and the uses of alloys
Atoms of pure metals are arranged very closely and orderly as shown in figure 8.1.
2.The layers of atoms slide easily over one another when a force is applied.as a result,it becomes ductile as shown in figure 8.2.
Figure 8.2 Ductile property of metal.
3.Ability of the layers metal atoms to slide easily also makes it malleable and easily shaped when a forced is applied as shown in figure 8.3.
In an alloy,substances added which are smaller or bigger fill the shapes between the pure metal atoms and the new arrangement is formed as shown in figure 8.4.
Figure 8.4 Alloy with smaller atoms.
Prevents the layers of pure metal atoms from sliding over one another.
Table 8.2 shows the comparison between a pure metal and alloy.
The importance of alloys in industry.
Stainless steel resistant to corrosion.
Differences ordinary conductor(Normal conductor) and superconductor.
Table 8.3 shows uses of superconductor alloys in industry and daily life.
8.2 Production and uses of ammonia in industry.
Pungent smell,colourless and very soluble in water.
Uses of ammonia and its compound in daily life.
Table 8.4 shows uses of ammonia and its compounds in daily life.
Production of ammonia in industry.
Haber process produce ammonia.
Nitrogen and hydrogen.
Hydrogen is produced by reacting methane with steam or from the cracking oil.
Iron powder is added as a catalyst.Booster like aluminium oxide.
The following shows the reaction in producing ammonia.
Figure 8.6 The haber Process
Factor influencing the production of ammonia:
Pressure 200-500 atmospheres.
Temperature Exothermic 450-500ºC
Catalyst increase the rate of a chemical reaction boosters activate the catalyst.
Uses of ammonia in industry.
Ammonia is also used in large quantities to produce Nitric acid.
Production of ammonium fertilisers.
Production of ammonium salt fertilisers.
The preparation of ammonium salt fertiliser in the science laboratory is as follows:
Production of urea.
Urea is produce through the following processes:
Heated 200ºC and pressure of 200 atmospheres.
The reaction between chemicals which produce urea is shown below.
8.3 Effects of industrial waste disposal on the environment.
Poisonous and harmful industrial activities causes the quality of the environment to be on the decline.
the two main pollution-causing industrial activities are:
The burning of fossil fuels.
the direct disposal of industrial wastes from facrtories.
Sources of pollution from manufacturing activities and the effects of imporer industrial waste disposal .
Burning of fossil fuels.
Fossil fuels such as diesel,oil and natural gas are burned in factories and electric power stations to generate heat energy and electrical power.
Gases such as carbon dioxide,carbon monoxide,sulphur dioxide,and nitrogen dioxide are released.because fossil fuels have high contents of carbon and sulphur.
Earth receives most of its energy from the sun.Energy is used to heat up the Earth's surface.Heat produced is in the form of infrared radiation.It reflects heat back into the atmosphere.70% of the sun's energy is radiated back into space.Earth is kept warm enough to support life.
Increase Earth's temperature by trapped heat in the atmosphere as shown in figure 8.8.
Figure 8.8 the green house effect
The greenhouse effect also causes other problems such as:
The weather becomes warmer.
The melting of ice.
desert areas bigger.
Figure 8.9 shows the contribution of different types of greenhouse gases towards global warming.
Greenhouse gases that contribute
towards global warming
Figure 8.10 Formation of acid rain
sulphur dioxide contributes to acid rain
Oxides of nitrogen contribute to acid rain.
The effects of acid rain:
Disturbs the equilibrium of nature
Acid rain affects lakes,streams,rivers,bays,ponds and other sources by increasing their acidity.This leads to the death aquatic organisms and plants.
Destroys plants and trees as the soil becomes too acidic.
Toxic chemicals,oils and untreated waste.
Pollutants also affect quantity of dissolved oxygen,affecting aquatic animals and plants.
Nuclear power stations and research institutions.
Radioactive produced nuclear research centres,nuclear reactors and manufactring products contain radioactive substances.
Radioactive radiations released by these sources into the surrounding.
Oil palm industry
Oil palm industry are stalks of fruit branches,fibre wastes and oil spill.
Oil palm wastes are disposed off by burning them or leaving them to rot.
Rubber wastes are made up of phospate salt,ammonia and rubber protein.
These wastes encourage the growth of bacteria.
Table 8.5 shows the types of pollutants,their sources and effects on living organisms.
Method of controlling industrial waste disposal.
Several ways to control the disposal of industrial wastes such as:
Environmental Quality (scheduled wastes)Regulation,1989
Environmental quality (Clean air)Regulation,1979
Variety of industrial wastes recycled for use as products.
Particulars industry can also be used by other industries if that industries if that industrial waste is suitable for them.
Public need to be educated about the importance of environmental cleanliness and the harmful effects of environmental pollution.
The mass media and schools plays important roles in spreading environmental awareness to the public.
Using electrostatic precipitator
Using a scrubber
Process agricultural wastes naturally through digestion by microorganisms.
Inside a digester drum called the Digester unit.
Temperature 30 ºC - 40 ºC
Figure 8.12 biogas digester
The separated methane is sent to houses for cooking purposes or to factories for Heating purpose.
Agricultural wastes are directly burned in a heating furnace.
Figure 8.13 shows the system which is used to burn agricultural wastes.
Figure 8.13 Component of the direct burning system.
Radioactive waste is radioactive material which may be left after a commercial or laboratory process has been carried out.
Radioactive wastes disposal drums which are made of strontium.
Disposal drums placed 200 metres below the soil surface.
Using electrostatic precipitor.
Electrostatic precipitator two collection plates:
Using a scrubber.
Scrubber is used to filter the poisonous gases by sparing a liquid onto the poisonous gases.
The toxic-free gas is then released.
figure 8.14 shows an air scrubber.
Figure 8.14 Air scrubber.
8.4 Preservation and Conservation of the Environment.
Preservation Environment refers to steps taken to maitain the environment as close to its Natural state as possible.
Conservation refers continuos managment of the environment to minimise damage to the environment.
Consequences of uncontrolled and haphazard disposal of industrial wastes.
Earth is in real danger.This can be proven through headlines in newspapers about the uncontrolled and haphazard disposal of industrial wastes.
Indusrtrial wastes can pollute water sources.Water sources become unsuitable for human consumption.Water pollution also threatens aquatic lives.
The importance of practising responsiblity in disposing wastes.
Humans must practice responsibility.
All wastes produced by industries must be stored,transported and disposed off properly.
A pollution-prevention hierarcy which emphasies on reducing the amount of toxic waste produced as shown in figure 8.15 must be implemented .stratergies involved include:
Reduce the amount of pollution at the source.
Recycle wastes wherever possible.
Treat wastes to minimise their hazards.
Disposal of wastes on land is carried out only as a last resort.
Figure 8.15 the pollution-prevention hieracy
Several ways to preserve and conserve the environment which include:
Control by authorities.
Use of technology.
Control by authorities.
The following laws are used to control the disposal of industrial wastes:
The Environmental Quality act 1974(Amendment 1985).
The Factory and machinery Act 1976(Revised 1983).
The pest Poison Act 1874
The government organised and participated in international conferences to discuss environmental world issues.There are:
The langkawi declaration (october 1991).
The Earth summit conferences (1992).
The agreements made in this conferences include:
Reducing the emission of carbon dioxide gas that causes global warming.
The protection of animals and plants to ensure they do not become extinct.
The Earth summit resulted in the following documents:
convention on biological diversity
Rio declaration on Environment and development.
Educating the public.
Every citizen has a responsibility in looking after the cleanliness and purity of the environment.
The preservation and conservation Environment can be spread through campaigns,mass media and the school syllabus.
Use of technology.
Pollution reduced by using modern technology.
Factories reduce pollutants in the air by installing filters.