Chemistry, a branch of physical science, is the study of the composition, properties and change of matter.[1][2] Chemistry is chiefly concerned with atoms and their interactions with other atoms - for example, the properties of the chemical bonds formed between atoms to create chemical compounds. As well as this, interactions including atoms and other phenomena - electrons and various forms of energy - are considered, such as photochemical reactions, oxidation-reduction reactions, changes in phases of matter, and separation of mixtures. Finally, properties of matter such as alloys or polymers are considered.Chemistry is sometimes called "the central science" because it bridges other natural sciences like physics, geology and biology with each other.[3][4] Chemistry is a branch of physical science but distinct from physics.[5]

The etymology of the word chemistry has been much disputed.[6] The genesis of chemistry can be traced to certain practices, known as alchemy, which had been practiced for several millennia in various parts of the world, particularly the Middle East.[7]

What is the scope of chemistry?Answer Scope of Chemistry is huge · Biochemistry 34% · Organic Chemistry9% · Analytical Chemistry · Inorganic Chemistry 27% · Physical Chemistry · Applied Chemistry and Chemical Engineering 21% · Macromolecules 9%

Chemistry

Branches of ChemistryChemistry can be divided into branches according to either the substances studied or the types of study conducted. The primary division of the first type is between inorganic chemistry and organic chemistry. Divisions of the second type are physical chemistry and analytical chemistry.The original distinction between organic and inorganic chemistry arose as chemists gradually realized that compounds of biological origin were quite different in their general properties from those of mineral origin; organic chemistry was defined as the study of substances produced by living organisms. However, when it was discovered in the 19th cent. that organic molecules can be produced artificially in the laboratory, this definition had to be abandoned. Organic chemistry is most simply defined as the study of the compounds of carbon. Inorganic chemistry is the study of chemical elements and their compounds (with the exception of carbon compounds).Physical chemistry is concerned with the physical properties of materials, such as their electrical and magnetic behavior and their interaction with electromagnetic fields. Subcategories within physical chemistry are thermochemistry, electrochemistry, and chemical kinetics. Thermochemistry is the investigation of the changes in energy and entropy that occur during chemical reactions and phase transformations (see states of matter). Electrochemistry concerns

the effects of electricity on chemical changes and interconversions of electric and chemical energy such as that in a voltaic cell. Chemical kinetics is concerned with the details of chemical reactions and of how equilibrium is reached between the products and reactants.Analytical chemistry is a collection of techniques that allows exact laboratory determination of the composition of a given sample of material. In qualitative analysis all the atoms and molecules present are identified, with particular attention to trace elements. In quantitative analysis the exact weight of each constituent is obtained as well. Stoichiometry is the branch of chemistry concerned with the weights of the chemicals participating in chemical reactions. See also chemical analysis.

Overview of the 5 Branches of Chemistry

Organic Chemistry - the study of carbon and its compounds; the study of the chemistry of life.

Inorganic Chemistry - the study of compounds not-covered by organic chemistry; the study of inorganic compounds or compounds which do not contain a C-H bond. Many inorganic compounds are those which contain metals.

Analytical Chemistry - the study of the chemistry of matter and the development of tools used to measure properties of matter.

Physical Chemistry - the branch of chemistry that applies physics to the study of chemistry. Commonly this includes the applications of thermodynamics and quantum mechanics to chemistry.

Biohemistry - the study of chemical processes that occur inside of living organisms.

History of chemistryThe 1871 periodic table constructed by Dmitri Mendeleev. The periodic table is one of the most potent icons in science, lying at the core of chemistry and embodying the most fundamental principles of the field.The history of chemistry encompasses a span of time reaching from ancient history to the present. By 1000 BC, ancient civilizations used technologies that would eventually form the basis of the various branches of chemistry. Examples include extracting metals from ores, making pottery and glazes, fermenting beer and wine, extracting chemicals from plants for medicine and perfume, rendering fat into soap, making glass, and making alloys like bronze.The protoscience of chemistry, alchemy, was unsuccessful in explaining the nature of matter and its transformations. However, by performing experiments and recording the results, alchemists set the stage for modern chemistry. The distinction began to emerge when a clear differentiation was made between chemistry and alchemy by Robert Boyle in his work The Sceptical Chymist (1661). While both alchemy and chemistry are concerned with matter and its transformations, chemists are seen as applying scientific method to their work.Chemistry is considered to have become a full-fledged science with the work of Antoine Lavoisier, who developed a law of conservation of mass that demanded careful measurements and quantitative observations of chemical phenomena. The history of chemistry is intertwined with the history of thermodynamics, especially through the work of Willard Gibbs.[1]

The scientific method is a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge.[1] To be termed scientific, a method of inquiry must be based on empirical and measurable evidence subject to specific

principles of reasoning.[2] The Oxford English Dictionary defines the scientific method as: "a method or procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses."[3]

The chief characteristic which distinguishes the scientific method from other methods of acquiring knowledge is that scientists seek to let reality speak for itself,[discuss] supporting a theory when a theory's predictions are confirmed and challenging a theory when its predictions prove false. Although procedures vary from one field of inquiry to another, identifiable features distinguish scientific inquiry from other methods of obtaining knowledge. Scientific researchers propose hypotheses as explanations of phenomena, and design experimental studies to test these hypotheses via predictions which can be derived from them. These steps must be repeatable, to guard against mistake or confusion in any particular experimenter. Theories that encompass wider domains of inquiry may bind many independently derived hypotheses together in a coherent, supportive structure. Theories, in turn, may help form new hypotheses or place groups of hypotheses into context.

Scientific inquiry is generally intended to be as objective as possible in order to reduce biased interpretations of results. Another basic expectation is to document, archive and share all data and methodology so they are available for careful scrutiny by other scientists, giving them the opportunity to verify results by attempting to reproduce them. This practice, called full disclosure, also allows statistical measures of the reliability of these data to be established (when data is sampled or compared to chance).

Formulation of a question: The question can refer to the explanation of a specific observation, as in "Why is the sky blue?", but can also be open-ended, as in "How can I design a drug to cure this particular disease?" This stage also involves looking up and evaluating previous evidence from other scientists, including experience. If the answer is already known, a different question that builds on the previous evidence can be posed. When applying the scientific method to scientific research, determining a good question can be very difficult and affects the final outcome of the investigation.[19]

Hypothesis: An hypothesis is a conjecture, based on the knowledge obtained while formulating the question, that may explain the observed behavior of a part of our universe. The hypothesis might be very specific, e.g., Einstein's equivalence principle or Francis Crick's "DNA makes RNA makes protein",[20] or it might be broad, e.g., unknown species of life dwell in the unexplored depths of the oceans. A statistical hypothesis is a conjecture about some population. For example, the population might be people with a particular disease. The conjecture might be that a new drug will cure the disease in some of those people. Terms commonly associated with statistical hypotheses are null hypothesis and alternative hypothesis. A null hypothesis is the conjecture that the statistical hypothesis is false, e.g., that the new drug does nothing and that any cures are due to chance effects. Researchers normally want to show that the null hypothesis is false. The alternative hypothesis is the desired outcome, e.g., that the drug does better than chance. A final point: a scientific hypothesis must be falsifiable, meaning that one can identify a possible outcome of an experiment that conflicts with predictions deduced from the hypothesis; otherwise, it cannot be meaningfully tested.

Prediction: This step involves determining the logical consequences of the hypothesis. One or more predictions are then selected for further testing. The less likely that the prediction would be correct simply by coincidence, the stronger evidence it would be if the prediction were fulfilled; evidence is also stronger if the answer to the prediction is not already known, due to the effects of hindsight bias (see also postdiction). Ideally, the prediction must also distinguish the hypothesis from likely alternatives; if two hypotheses make the same prediction, observing the prediction to be correct is not evidence for either one over the other. (These statements about the relative strength of evidence can be mathematically derived using Bayes' Theorem.)Testing: This is an investigation of whether the real world behaves as predicted by the hypothesis. Scientists (and other people) test hypotheses by conducting experiments. The purpose of an experiment is to determine whether observations of the real world agree with or conflict with the predictions derived from an hypothesis. If they agree, confidence in the hypothesis increases; otherwise, it decreases. Agreement does not assure that the hypothesis is true; future experiments may reveal problems. Karl Popper advised scientists to try to falsify hypotheses, i.e., to search for and test those experiments that seem most doubtful. Large numbers of successful confirmations are not convincing if they arise from experiments that avoid risk.[21] Experiments should be designed to minimize possible errors, especially through the use of appropriate scientific controls. For example, tests of medical treatments are commonly run as double-blind tests. Test personnel, who might unwittingly reveal to test subjects which samples are the desired test drugs and which are placebos, are kept ignorant of which are which. Such hints can bias the responses of the test subjects. Failure of an experiment does not necessarily mean the hypothesis is false. Experiments always depend on several hypotheses, e.g., that the test equipment is working properly, and a failure may be a failure of one of the auxiliary hypotheses. (See the Duhem-Quine thesis.) Experiments can be conducted in a college lab, on a kitchen table, at CERN's Large Hadron Collider, at the bottom of an ocean, on Mars (using one of the working rovers), and so on. Astronomers do experiments, searching for planets around distant stars. Finally, most individual experiments address highly specific topics for reasons of practicality. As a result, evidence about broader topics is usually accumulated gradually.Analysis: This involves determining what the results of the experiment show and deciding on the next actions to take. The predictions of the hypothesis are compared to those of the null hypothesis, to determine which is better able to explain the data. In cases where an experiment is repeated many times, a statistical analysis such as a chi-squared test may be required. If the evidence has falsified the hypothesis, a new hypothesis is required; if the experiment supports the hypothesis but the evidence is not strong enough for high confidence, other predictions from the hypothesis must be tested. Once a hypothesis is strongly supported by evidence, a new question can be asked to provide further insight on the same topic. Evidence from other scientists and experience are frequently incorporated at any stage in the process. Many iterations may be required to gather sufficient evidence to answer a question with confidence, or to build up many answers to highly specific questions in order to answer a single broader question.

1. Famous Chemists and What They Discovered

Svante Arrhenius (1859 -1927) - He was initially a physicist but more popular as a

chemist because, he was the one who proposed the equation now known as the Arrhenius equation. He was also one of the first chemists who proposed that when in a solution the salt dissociates into ions even in the absence of an electric current.

Amedeo Avogadro (1776 - 1856) - He is known for proposing the Avogadro's Law which states that, "Equal volumes of gases contain the equal number of molecules when the given temperature and pressure are same for all the gases." The number of molecules present is known as, Avogadro's number and is 6.023 x 1023

Jons Jacob Berzelius (1779 - 1848) - He was Swedish and gave the technique of chemical formula notations. He also proposed the law of constant proportions, which proved that inorganic substances are made of elements that are in constant proportion by weight.

Marie Curie (1867 - 1934) - She was a Polish born chemist and physicist who later acquired French citizenship. She is renowned for her discoveries in the phenomenon of radioactivity. Marie Curie discovered the radioactive elements radium and polonium for which she was awarded the Nobel Prize in Chemistry.

John Dalton (1766 - 1844) - He was an English who is well-known for his discovery of atoms and the theory known as John Dalton's atomic theory. He stated that an atom is a fundamental unit of matter and these atoms can neither be created nor destroyed.

Michael Faraday (1791 - 1867) - He was a physicist who made contributions in the field of electrochemistry and electromagnetism. In the field of chemistry, it was Michael Faraday who discovered the aromatic compound benzene.

Joseph Louis Gay-Lussac (1778 - 1850) - He was French and physicist who is known for his work on gases. He proposed the Gay-Lussacs Law which states that, "At constant mass and pressure values, the volume of a gas increases linearly with temperature."

Dorothy Mary Hodgkin (1910 - 1994) - She was a British chemist who used the technique of X-ray crystallography to elucidate the structures of biomolecules. She also won the Nobel Prize in Chemistry for her work in protein crystallography.

Henri Louis Le Chatelier (1850 - 1936) - He proposed the principle for chemical equilibrium, known as the Le Chatelier's principle.

Dmitri Ivanovich Mendeleev ( 1834 - 1907) - A Russian, he was the one who charted the first periodic table, which has now undergone a lot of modifications. The table however, was so designed that there was scope to fit in new elements which were yet to be discovered then.

These were just a few of the best known chemists. There are many others who have made a noteworthy contribution to the subject of chemistry. We definitely owe a note of gratitude towards all these famous scientists, who have a vital role to play in the progress and development of mankind.

beaker - a liquid-measuring container2. burette - measures volume of solution3. clay triangle - a wire frame with porcelain used to support a crucible4. wire gauze - used to spread heat of a burner flame5. test tube - used as holder of small amount of solution6. forceps - holds or pick up small objects7. graduated cylinder - measures approximate volume of liquids8. graduated pipette - measures solution volumes

9. condenser - used in distillation10. crucible - used to heat a small amount of a solid substance at a very high temperature11. funnel - used to transfer solids and liquids without spilling12. thermometer - measures temperature13. balance - measures mass of material14. pH meter - measures acidity of solutions15. centrifuge - separates materials of varying density16. pipette - used to transfer measured substances into another vessel17. droppers - for addition of liquids, drop by drop18. glass funnels - for funneling liquids from one container to another, or for filtering when

equipped with filter paper.19. graduated cylinders - for measurement of an amount of liquid. The volume of liquid can

be estimated to the nearest 0.1 mL with practice.20. ring stand (with rings or clamps) - for holding pieces of glassware in place.21. test tubes - for holding small samples or for containing small-scale reactions22. test-tube holders - for holding test tubes when tubes should not be touched23. tongs - similar function to forceps, but are useful for larger items24. volumetric flasks - to measure precise volumes of liquid or to make precise dilutions.25. wash bottles - for dispensing small quantities of distilled water.26. watch glasses - for holding small samples or for covering beakers or evaporating dishes.27. wire gauze on a ring - supports beakers to be heated by Bunsen burner.

Protective Clothing

Labatory coats can help protect your skin from spills. Personal safety is a primary concern in a laboratory, starting with the appropriate attire. Basic protective clothing for this environment include: laboratory apron, splash-resistant goggles and gloves. Shoes need to have a covered-toe design, and you should avoid wearing heels, sandals or clog-style shoes. The clothing that you wear in the laboratory needs to be washed in a separate load. Clothing should also cover the skin and fit snugly to your body.

Cleanliness Keeping the laboratory clean is a key preventative measure to avoid accidents.

Equipment should be organized and properly stored to avoid clutter. Hallways and staircase landings should not be used for storage. Areas around fume hoods, table tops, passage ways and floors should be clear of clutter and cleaned with a disinfectant spray. The floor needs to be kept dry, and spills should be cleaned up quickly to avoid falls. When work in the laboratory is finished, the area should be cleaned up and you should wash your hands.

Laboratory Equipment

Equipment in the laboratory should be carefully inspected before using it, and any damaged items should be replaced. The equipment should also have any necessary maintenance performed as recommended by the manufacturer. Fume hoods should be utilized whenever you are working with any type of chemical. You should ensure that guards and protective shields are on any mechanical equipment to prevent injury. Fume hoods should not be utilized as a storage area for various chemicals, unless it has a built-in storage space.

Dealing with Chemicals

Chemical containers have to be carefully handled and stored.

You need to have a thorough understanding of the various chemicals, their properties and how to properly store them. When storing chemicals, you need to keep ones that are not compatible in a separate space. This is especially true for those that are explosive, corrosive or can catch on fire. When carrying chemicals, use a carrier and make sure that the lids are securely fastened. All bottles need to be clearly labeled with the contents and should be dated.