Basic Concepts of Chemistry

JEE stuff

What is matter?

Anything which occupies space and has mass.

What are pure substances?

All constituent particles of the substance have the same chemical nature.

What is a mixture?

A substance that contains particles of two or more pure substances which may be present in any ratio.

What is a homogenous mixture?

Composition of the mixture is uniform throughout.

What is a heterogeneous mixture?

Composition of the mixture is not uniform throughout.

Elements?

Can neither be decomposed nor built from simpler substances by ordinary physical and chemical methods. It contains only one kind of atoms.

Most abundant element in the universe?

Hydrogen

Most abundant element in the Earth’s crust?

Oxygen

Most abundant metal in the earth’s crust?

Aluminium

What are compounds?

Forms of matter that can be formed by combining two or more elements in a definite ratio by mass.

What are organic compounds?

Hydrides of carbon (hydrocarbons) and their derivatives

What are inorganic compounds?

Compounds of all elements except for hydrides of carbon (hydrocarbons) and their derivatives.

What does the suffix ‘micro’ mean?

10^-6

What does the suffix ‘milli’ mean?

10^-3

What does the suffix ‘nano’ mean?

10^-9

What does the suffix ‘pico’ mean?

10^-12

What does the suffix ‘femto’ mean?

10^-15

What does the suffix ‘atto’ mean?

10^-18

What is precision?

It is the closeness of the set of values obtained from identical measurements of a quantity.

What is accuracy?

It is a measure of the difference between the experimental value or the mean value of a set of measurements and the true value.

How much is amstrong in metres?

10^-10m

How much is 1 eV in Joules?

1.602189 * 10^-19 J

How much is 1 calorie in Joules?

4.184 J

How much is 1 bar in pascal and N m^-2?

10⁵ Pa and 10⁵ N m^-2

How much is 1atm in pascal and N m^-2?

101325 in both units

How much is 1 dyne in Newtons?

10⁵ N

How much is 1 Litre in decimetre³?

1 dm³

How much is 1 Litre in m³?

10^-3 m³

What is Law of Conservation of Mass?

What is Law of Definite Proportions?

What is Law of Multiple Proportions?

What is Law of Reciprocal Proportions?

What is Gay Lussac’s Law of Gaseous Volumes?

What is Avogadro’s Hypothesis?

What are the basic postulates of Dalton’s Atomic Theory?

1. All substances are made up of tiny, indivisible particles, called atoms.

2. In each element, the atoms are all alike and have the same mass. The atoms of different elements differ in mass.

3. Atoms can neither be created nor destroyed during any physica or chemical change.

4. Compounds or molecules result from combination of atoms in some simple numerical ratio.

What are the limitations of Dalton’s Atomic Theory?