Chapter 2 : Basics of Chemistry
Topics covered in this snack-sized chapter:
It is the branch of science that deals with the identification of the substances of which matter is composed.
- It also deals with the investigation of their properties and the ways in which they interact, combine and change.
- It also deals with the use of the processes to form new substances.
Disciplines within chemistry are traditionally grouped by the type of matter being studied or the kind of study.
These include the following:
Inorganic chemistry
- The study of inorganic matter.
Organic chemistry
- The study of organic (carbon-based) matter.
Biochemistry
- The study of substances found in biological organisms.
Physical chemistry
- The study of chemical processes using physical concepts, such as thermodynamics and quantum mechanics.
Analytical chemistry
- The analysis of material samples to gain an understanding of their chemical composition and structure.
Neurochemistry
- The chemical study of the nervous system.
Several concepts are essential for the study of chemistry.
Some of them are as follows:
- Matter and its classification
Matter includes atoms and other particles which have mass.
Matter is anything that occupies space and has mass.
There are five main states of matter:
- Bose-Einstein condensates.
Solids: Have a rigid shape and fixed volume.
Liquids: Have no fixed shape and may not fill a container completely.
Gases: Expand to fill the container.
Plasma: The fourth state of matter.
- Plasma is an ionized gas, a gas into which sufficient energy is provided to free electrons from atoms or molecules and to allow species, ions and electrons to coexist.
Bose-Einstein Condensates:
- Recently, scientists have discovered the Bose-Einstein condensate, which can be thought of as the opposite of plasma.
- It occurs at ultra-low temperature, close to the point that the atoms are not moving at all.
- A Bose-Einstein condensate is a gaseous superfluid phase formed by atoms cooled to temperatures very near to absolute zero.
| Extensive Property
| Depends upon how much matter is being considered.
Examples:
Mass
Length
Volume
|
| Intensive Property
| Does not depend upon how much matter is being considered.
Examples:
Density
Temperature
|
A mixture is a combination of two or more substances in which the substances retain their distinct identities.
Homogeneous mixture – Composition of substances is the same throughout.
Example:
Heterogeneous mixture – Composition of substances is not uniform throughout.
Example:
An atom is the basic unit of chemistry.
It consists of a positively charged atomic nucleus, which contains protons and neutrons.
It also maintains a number of electrons to balance the positive charge in the nucleus.
A chemical element is specifically a substance that is composed of a single type of atom.
A chemical element is characterized by a particular number of protons in the nuclei of its atoms.
This number is known as the atomic number of the element.
- 116 elements have been identified.
- 82 elements occur naturally (Example: gold).
- 34 elements have been created by scientists (Example: americium).
A compound is a substance with a particular ratio of atoms of particular chemical elements.
This ratio determines its composition and its particular organization.
Example: Water
A chemical substance is a kind of matter with a definite composition and a set of properties.
Acidity and Basicity of Substance
A substance can often be classified as an acid or a base.
There are several theories which explain acid-base behavior.
The simplest is Arrhenius theory, which states that:
- “An acid is a substance that produces hydronium ions when it is dissolved in water, and a base is one that produces hydroxide ions when dissolved in water.”
A molecule is the smallest indivisible portion of a pure chemical substance.
It has its unique set of chemical properties.
The concept describes the state in which the parameters such as chemical composition remain unchanged over time.
Atoms sticking together in molecules or crystals are said to be bonded with one another.
A chemical bond may be visualized as the balance between:
- The positive charges in the nuclei and the negative charges oscillating about them.
An ion is a charged species, an atom or a molecule, that has lost or gained one or more electrons.
- Positively charged species are called cations (e.g., sodium cation Na+
).
- Negatively charged species are called anions (e.g., chloride Cl−
).
Chemistry has been further divided into different branches depending upon specialized fields of study.
This branch deals with the study of compounds of all other elements except carbon.
It mainly deals with the study of minerals found in the crust of earth.
This branch deals with the study of carbon compounds especially hydrocarbons and their derivatives.
Organic chemistry defines life.
Beyond our bodies' DNA, peptides, proteins and enzymes, organic compounds are all around us.
They are a source of energy: We obtain energy from organic compounds like carbohydrates (sugars) and fats, using amino acids and proteins (organic) to grow.
Genetic information transmission: from one generation to the next, through organic compounds called nucleic acids.
- Body parts formation: Organic chemicals make up our Hair, Skin and Fingernails.
This branch deals with the explanation of fundamental principles governing various chemical phenomena.
It is basically concerned with the laws and theories of different branches of chemistry.
This branch deals with the chemistry involved in industrial process.
This branch deals with the qualitative and quantitative analysis of various substances.
This branch deals with the chemical changes going on in the bodies of living organisms; plants and animals.
This branch deals with the study of nuclear reactions such as nuclear fission, nuclear fusion etc.
In addition to above branches there are other branches of chemistry developed in recent years.
These include pharmaceutical chemistry, geo-chemistry, agricultural chemistry, medicinal chemistry, solid state chemistry etc.
Chemistry plays very significant role in almost all walks of life. Our daily life involves the use of many chemical products and many chemical changes although we are unaware of them.
Some of the major contributions of chemistry to the life in modern world are as given below:
Modern chemical discoveries have done a lot to eradicate disease and to improve health.
Some important contributions of chemistry in the field of medicines are development of:
- Lifesaving drugs like Taxol and cisplatin (used in cancer therapy); azidothymidine (AZT) used for AIDS victims.
- Prophylactics i.e. disease preventing screen and vaccines
- Anaesthetics and antiseptics.
- Disinfactants and germicides.
The major contribution of chemistry in the field of Industry is the use of:
- Synthetic fiber like rayon, nylon, dacron, orlon etc.
- Plastics like Bakelite, teflon, polythene etc.
- Paints, varnishes, enamels, dyes etc.
- Cement, glass and ceramics and extraction of metals like silver, magnesium, gold iron, etc.
The major contribution of chemistry in the field of agriculture is the use of:
- Chemical fertilizers like urea, ammonium sulphate, calcium nitrate, etc. for the better production of crops.
- Insecticides such as D.D.T., gammexane, methoxychlore etc., for the protection of crops from insects and help the safe storage of food grains.
- Preservatives like sodium benzoate, sodium metabisulphate and salicylic acid for better preservation of food and check its wastage.
Chemistry in Comfort, Convenience and Pleasure:
Domestic requirements such as paper, fabrics, soaps, cosmetics, oils, flavoring essences, dyes and perfumes.
Air conditioning: To keep efficient in all seasons we make use of air conditioning. In this we use chemical substances like liquid ammonia or liquid sulphur dioxide.
Chemistry and Energy Resources:
The energy resources of the world are petroleum, coal, wood and nuclear fuels.
The reserves of coal and petroleum are being exhausted at a fast speed; therefore attempts are being made by chemists to utilize the nuclear energy and solar energy for meeting our requirements.
Hydrogen from sea water may provide an inexhaustible source for future energy needs.
Like most of the human achievements, chemistry has been used as well as misused.
On one side it has contributed so much for the benefit of our society.
On the other hand, it has endangered the society by providing explosives such as TNT, RDX, other deadly chemical weapons of destruction, atomic and hydrogen bombs.