Chemistry is the study of the composition,structure, properties and interactions of matter
In retrospect, the definition of chemistry seems to invariably change per decade, as new discoveries and theories add to the functionality of the science. Shown below are some of the standard definitions used by various noted chemists:
Alchemy (330) – the study of the composition of waters, movement, growth, embodying and disembodying, drawing the spirits from bodies and bonding the spirits within bodies (Zosimos).Chymistry (1661) – the subject of the material principles of mixt bodies (Boyle).Chymistry (1663) – a scientific art, by which one learns to dissolve bodies, and draw from them the different substances on their composition, and how to unite them again, and exalt them to an higher perfection (Glaser).Chemistry (1730) – the art of resolving mixt, compound, or aggregate bodies into their principles; and of composing such bodies from those principles (Stahl).Chemistry (1837) – the science concerned with the laws and effects of molecular forces (Dumas).Chemistry (1947) – the science of substances: their structure, their properties, and the reactions that change them into other substances (Pauling).Chemistry (1998) – the study of matter and the changes it undergoes (Chang).
Chemistry is a branch of science that studies the properties of substances and the products that are formed when substances mix and join together.
The study of chemistry aims to understanda) The structure and behaviour of substancesb) The composition and properties of substancesc) The reactions between substances and the accompying energy exchanges
Common chemical substances and their uses
Acetic acid - as food preservatives, manufacture of paintAlcohol - Used in perfumes, furniture polishAluminium - Body in aircraft, kitchen foilsAmmonia - Manufacture of fertilisers, prevents coagulation of latexCalcium hydroxide = manufacture of cement adn plasterChlorine - used as disinfectant for swimming pool , making bleachFlouride - toolpaste and drinking water to prevent tooth decayIodine - used in antiseptics, medicineIron - making stee., construction of cars and buildingsKerosene - fuels fro jet aircraft , used in kerosene lampsMonosodium glutamate - seasoning to boost the flavour in foodSilicon dioxide - manufacture of glass and construction of materials
Robert Boyle (1627 - 1691) an Irish Scientist known as Father of Moderm Chemistry, was one of the first prominetn scientist to perform controlled experiments and publish his works with elaborate details of his experiments.
Importance of Chemistry
Overview of the Scientific MethodThe scientific method is a process for experimentation that is used to explore observations and answer questions. Scientists use the scientific method to search for cause and effect relationships in nature. In other words, they design an experiment so that changes to one item cause something else to vary in a predictable way.Just as it does for a professional scientist, the scientific method will help you to focus your science fair project question, construct a hypothesis, design, execute, and evaluate your experiment.
| Substances | Uses |
| Acetic acid | As food preservatives, manufacuture of paint |
| Alcohol | Used in perfumes, funiture polish |
| Aluminium | Body of aircraft, kitchen foils |
| Ammonia | Manufacture of fertilizer, prevents coagulation of latex |
| Calcium Hydroxide | Manufacture of cements and plaster |
| Chlorine | Used as disinfectant for swimming pool, making bleach |
| Flouride | In tooth paste and drinking water to prevent tooth decay |
| Iodine | Used in antiseptics, medicine |
| Iron | Making steel, construction of cars and building |
| Kerosene | Fuel for jet aircraft and lamps |
| Monosodium glutamate | Seasoning to boost flavour of food |
| Silicon dioxide | Manufacture of glass |
| Silver bromide | Used in photography films |
| Sodium hydroxide | Manufacture of soaps and paper |
| Detergent | Manufacture of detergents, used in car batteries |
| Urea | Manufacture of fertilizers |
| Vinyl chloride | Used in water pipes and toys |
The importance of ChemistryMaterials made in the chemical industry are all around us and even in our bodies.Raw materials enter the industrial plants where chemical reactions take place to change these raw materials into useful materials.
Agriculture - Fertilizer, weed killer, pesticides, organic farmingBuilding and Construction - Alloys, steel, coal paint , adhesives, glassClothing and fashion - Dyes, pigments, cosmetics, synthetic fibres such as nylon, rayon and polyesterCommunication - Optic fibres, microelectronics, chemical cells, paperFood - Preservatives, food additives, colourings, falvourings, antioxidants, fermented food, cheeseHousehold - Soap, detergent, ceramics, steel cutlery, plastic containersMedicine - Antibiotics, vitamins, hormones, drugs, antisepticsTransport - Fuels, glass, alloy and metal bodies of vehicles.
Carrer in the field of chemistry
a) Doctor - a person who treats people who are ill.b) Biochemist - a person who studies chemcial processes in libing thingsc) Dietician - a person who advises people on what they should or should not eat ub order to be healtyd) Food technologist - a person who conducts experiments on food to find out if they are safe to ber consumede) Pharmacist - aperson who checks the safety of drugs and medicine.f) veterination - a person who looks after the health of animalsg) Material scientist - a person who does research on the porperties of materialsh) Metallurgist - a person who does studies the properties and uses of metalsi) Forensic scientist - a person who investigates a crime by scientifically examining the object involved in it.
Scientific Method
The scientific method or scientific process is fundamental to scientific investigation and to the acquisition of new knowledge based on physical evidence by the scientists.Scientists use observations and reasoning to propose tentative explanations for natural phenomena, termed hypotheses.The scientific method is a systematic approach to research. It consists of the following steps:
Steps in the Scientific MethodMaking observationAn investigation usually begins with an observation on a phenomenon.Observation is to observe and gather the information about the phenomenon.Phenomenon refers to situation or condition which is being observedExample : Salt dissolves easily in hot water compared to cold water.
Making Inference After gathering sufficient information, we make an inference, or early conclusion, based on what has been observed. The inference may or may not be true and need to be proven true or false with further investigation.
Identifying problem Asking question based on the inference made to identify the problem related to the observation.
Making a hypothesis A hypothesis is a proposed explanation for a phenomenon.Normally, it is a general statement about the relationship between the manipulated variable and a responding variable in order to explain the question ask.This is what we called SMART GUESS.
Identifying variables A variable is a factor that affects other factors in an experiment.In a scientific investigation, we need to identify all related variables.There are three types of variable, namelyManipulated variable — the factor that is purposely changed in an experimentResponding variable — the factor that changes with the manipulated variableFixed variables — the factors that are kept constant throughout an experiment. This is to ensure that other factors do not affect the results of the experiment.
Controlling variables Deciding how to repeat the experiment several times by using different values of the manipulated variable.This step is to test the consistency in the experiment and also to relate the manipulated variable to the responding variable.
Designing the experiment Deciding how to carry out the experiment, including determine the material, apparatus, experiment sets out and the procedure to take.Always keep in mind that the main purpose of the experiment is to o test the hypothesis.
Carrying Out the Experiment After the planning of the experiment is done, you will need to carry out the experiment according to the procedure.
Collecting data Make observations in the experiment by watching and measuring.Measure the quantities accurately using suitable measuring instruments and units.All data are collected and recorded in a proposed table.
Analysing and interpreting data After collecting the data, you will need to analyse the results of the experiment.Data analysis is the step to studies information by breaking it down into smaller parts.The results can be presented in various forms, such as a table, graph or chart.
Making a conclusion Draw conclusions based on the observations and results.State whether the hypothesis is true or false.
Writing the report A report is written after an experiment is performed.The format of the report is arranged based on the scientific investigation method which is performed systematically; starting from the problems identified to the last stage.State any precautions taken to overcome problems in the experiment.A simple diagram of the experiment set-up would sometime be useful.
Scientific attitudes and values in scientific investigations
It is important to practise the right attitude and values when conducting investigation.Among thema) Show interest, curiosity and open mindedness when conducting investigationsb) Be precise and honest when recording observations, measurement and datac) Be systematic and organized when conducting experiments and collecting data.d) Think objectively and rationally when analysing and interpreting datae) Be co-operative and responsible when donducting experimentsf) Give clear and concise statement of inferences, hypothesis, experimental procedures, observations, precautions and conclusions.
Studnets should also demonstrate good laboratory skills, such asa) Keeping the work area cleanb) not suing more chemicals than needed to reduce wastagec) using proper procedures when lighting the bunsen burnerd) checking and using all electrical equipment with caree) typing back long hair and securing loose clothingf) being mindful of body movements and those around you when conducting experiments
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