Terminology: Basic Terms Used in Chemistry

The following are the terms that are used in chemistry very frequently.

Element: a chemical element is a substance that cannot be broken down by chemical means. For example, hydrogen, oxygen etc.

Atom: the smallest particle of a chemical element that can exist. For example, the basic unit of hydrogen element is hydrogen atoms. An element has the same kind of atoms.

Compound: A compound is a substance formed when two or more chemical elements are chemically bonded together. For example, HCl, NaCl etc.

A molecule of an element: when the same kind of element combines together, they form a molecule of an element. For example, H₂, Cl₂, O₂, S₈, P₄ etc.

A molecule of a compound: when different elements combine together in a fixed ratio, they form a molecule of a compound. For example, 8g of oxygen combines with 1g of hydrogen to form 9g of water.

Mixture: a substance made by mixing two or more substance together in any proportion. A mixture is of two types.
a. Homogeneous mixture: a mixture which has the same proportion of its components throughout any given sample. For example, alloys.
b. Heterogeneous mixture: a mixture whose proportion vary throughout the sample. For example, mud or sand in water.

Temperature: it is a measure of the hotness or the coldness of the environment.

Pressure: it is the force exerted by the substance per unit area. The pressure of a gas is the force that the gas exerts on the walls of its container.

P = F÷A

Where, P = pressure

F = force exerted

A = area of cross section

It's SI unit is N/sq. m

Volume: it is a 3-D space enclosed by a closed surface.
V = L × B × H
Where L is the length
B = breadth
H = height of the container.
Its SI unit is the cubic metre.

Density: it is a measure of how much stuff an object has in a unit volume.
Density = mass/volume.

It's SI unit is g/L.

Bond: it is the force holding atoms together. For example, the force between Na and Cl is known as an ionic bond.

" A chemical bond is not a line (as shown in covalent or coordinate bonds), it is a force holding things together."

Physical property: properties that do not change the chemical nature of the matter. For example, melting point, odour, colour, physical appearance, refractive index etc.

Chemical property: properties that change the chemical nature of the matter. For example, chemical reactions.

Mass: it is the amount of matter an object has. It does not change with place or centre of gravity. It is generally taken in kg.

Weight: it is the force exerted on an object due to the acceleration of gravity.
W = mg
Where, W = weight
m = mass of the object
g = acceleration due to gravity ( 9.8m/s²)

Chemical equation: it is a symbolic representation of a chemical reaction in the form of symbols and formulae. In this, the reactants are written on the left-hand side and products on the right-hand side.
Example, Cu + H₂SO₄ → CuSO₄ + H₂

Valency: it is the combining power of an element with other atoms when it forms a chemical compound.
Or, valency is the number of electrons gained or lost in order to complete the octet.
For example, the valency of Na is 1 as it loses 1 electron to attain noble gas configuration while valency of S is 2 as it gains 2 electrons to complete its octet.

These terms will be helpful in your studies.

Phase transition

Interconversion of one state of matter to another state of matter is known as phase transition. The three states of matter, i.e. solid, liquid and gas, can interchange into each other under different conditions of temperature and pressure. Let us understand this one by one:

Conversion of solid to

a. Liquids: This process is known as melting. For example, melting of ice cream.

Melting point: It is the temperature at which the solid phase changes to the liquid phase or the temperature at which the solid-liquid state is in equilibrium.

b. Gas: This process is known as sublimation. For example, conversion of solid camphor to vapors.

"Phase transition is a physical process."

Conversion of liquid to
a. Solid: is known as freezing. For example, changing of liquid water to ice.

b. Gas: is known as vaporization. For example, changing of liquid water to water vapor.

Boiling point: The temperature at which the liquid changes to gaseous state or the temperature at which liquid-gas exist in equilibrium.

Conversion of gas to
a. Solid: is known as deposition.
b. Liquid: is known as condensation.

Latent heat of fusion: The amount of heat energy absorbed or released when a solid change to liquids at atmospheric pressure at its melting point is known as latent heat of fusion.

For example, when water changes its phase from solid to liquid, a lot of energy is utilized but the temperature does not change. The energy is consumed but no effect on temperature is visible. Hence, the name latent heat (i.e. hidden heat).

Latent heat of vaporisation: The amount of heat energy absorbed or released when a liquid changes to gaseous at its boiling point is known as latent heat of vaporisation.

Matter and its states

The matter is anything that has mass and occupies space. Matter exists in different phases, also known as states of matter.

Theoretically, more than 27 states of matter are known, most of which are condensates, i.e., exist at a very low temperature or under drastic conditions. But only 5 states are well-established. These are solid, liquid, gas, plasma and bose-einstein. These are classified according to the force of attraction between the particles.

1. Solid: In this, particles are packed very tightly. As a result, they have
a. strong force of attraction.
b. fixed shape, size, and volume.
c. least compressible.
d. negligible or no diffusion.

2. Liquids: In liquids, particles are packed comparatively loosely. As a result, they do not have strong force of attraction between the particles. They can
a. take the shape of the container in which it is poured.
b. be compressed when pressure is applied.
c. show the process of osmosis.

3. Gas: The particles in gases are very far apart since they have a little force of attraction between the particles. As a result, they are
a. highly compressible.
b. occupy the whole container.
c. highly diffusible.

The liquids and gases are known as fluids (to flow).

4. Plasma: Though this state of matter is not so common on our planet, it is the most common state of matter that is found in our universe. For example, stars, sun etc. Today, various inert gases are ionized using electricity so as to make glowing sign boards.

5. Bose-einstein condensate: In this, the atoms are supercooled to the temperature at which all the molecular motion ceases. At this stage, the atoms start to join together and form a cluster of atoms known as a super atom. They are also known as superfluids as they can flow without friction.
This state was named after two renown scientist, i.e., Albert Einstein and Satyendra Nath Bose.

"Vapour is not a state of matter."

Vapour is an equilibrium state between the gaseous state and the liquid or solid state, which can come back to its original state when pressure is applied on it, keeping the temperature constant or at standard condition of pressure and temperature.

*Description of every state will be posted later in this blog.

Why we use copper for electrical wirings?

We cannot imagine our lives without electricity. It makes our lives so comfortable. You can use technology and various appliances like AC, TV, washing machines, computers, lights and fan, etc. with the help of electricity. 

Even in big industries, a lot of work is done with the help of machines, that runs on the electricity.

Electricity is chiefly provided to us via using wires. From a very old time, copper wires are used for this purpose. Though there are other matters which have higher conductivity than copper wires but still use of copper wires is widespread.

" In supplying electricity to our houses by copper wires, more than 60% of the energy gets wasted."

The following are the reasons for using copper for electrical purposes:

1. Copper is malleable and ductile in nature and can be drawn into wires.

2. It is a good conductor of electricity.

3. According to Joules heating effect of current, when the electric current passed through a solid or a liquid, electric current is converted to heat energy. If more current is passed through the circuit, the wires might melt resulting in breaking the circuit. To avoid this situation, copper is used as it has high melting and boiling point.

4. It is comparatively cheaper.

5. It is easily and readily available.

Though silver is a better conductor than copper, it is not used because
1. It is expensive.
2. Silver can tarnish easily.

WHAT IS CHEMISTRY?

Chemistry is the branch of science which deals with the study of matter and its interaction either with another matter or with the wave.

When matter interacts with matter, physical and chemical changes occur. For example, when we make tea, we mix milk and water. But in doing so, no new substance is formed and it is called a physical change. Then, we add tea leaves and boil this mixture. We observe a change in colour, odour, taste etc. because a new product is formed. Hence, it is known as a chemical change. In this, the water, milk, and tea leaves are all matter and they interact with each other to form a new product.

The matter can also interact with the waves and as a result, the chemical reaction occurs. A common example is the use of microwave ovens for cooking food. Food, a matter, and the radiations from microwave ovens interact with each other and a new substance is formed.
Being a chemist or a chemistry student, it is our work to study all these changes so as to know the basic nature of each and every particle in the universe.

" Chemistry is the study of matter."

Chemistry works in combination with other disciplines. It makes use of logic and reasoning, mathematics, physics, biology, geology etc. Some common relationships are given below.

With mathematics:  for solving numerical, for preparing solutions of various concentrations.

With physics: there are many laws in physics which we use in chemistry, like Law of Conservation of Mass/Energy, Or quantum mechanics, radioactivity etc.

With biology: by using chemical laws and reactions, we make so many products which are useful in our daily life. Also, some of the products affect the lives of other organisms. For example, the use of DDT as a pesticide.

With geology: it is useful in the study of metallurgy for mining and extracting minerals from ores.

With logic: Every science needs logic to work. If something is not logical, it is beyond our mind.

" Chemistry is known as the central science."