Atoms and Molecules long 2

Question 1

What is the atomic theory ?

Answer 1

John Dalton gave a theory which was based on the laws of chemical combination. The theory states all matter are composed of small particles called atoms.

(i) All matter is made of very tiny particles called
atoms, which participate in chemical reactions.
(ii) Atoms are indivisible particles, which cannot be
created or destroyed in a chemical reaction.
(iii) Atoms of a given element are identical in mass
and chemical properties.
(iv) Atoms of different elements have different masses
and chemical properties.
(v) Atoms combine in the ratio of small whole numbers
to form compounds.
(vi) The relative number and kinds of atoms are
constant in a given compound.

Question 2

What is the relative atomic mass of the
atom of an element ?

Answer 2

It is defined as the average mass of the atom and said to be 1/12th the mass of one carbon-12 atom.

Question 3

How do atoms exist ?

Answer 3

Atoms of most elements are not able to exist independently. Atoms form molecules and ions. These molecules or ions bulk up in large numbers to form the matter that we can see, feel or touch.