Question

(a) Calculate the gram molecular mass of water from the values of gram atomic mass of hydrogen and oxygen.
Gram atomic mass of hydrogen $=1g$
Gram atomic mass of oxygen $=16g$
(b) Modern atomic theory takes up the wave concept, principles of uncertainity and other latest discoveries to give a clear-cut picture about an atom. State any three findings of modern atomic theory.

Answer 1

(a)Gram molecular mass of water

It has 2 atoms of hydrogen and 1 of oxygen.

$\therefore Grammolecularmass=2\times 1+16$ =18g,

(b) The findings of modern atomic theory are:

(i) Atom is considered to be divisible particle.
(ii) Atoms of the same element may not be similar in all respects
eg: Isotopes $C{l}_{17}^{35}$ and $C{l}_{17}^{37}$
(iii) Atoms of different elements may be similar in some respects.
eg: Isobars $C{l}_{40}^{18}$ and $C{l}_{40}^{20}$
(iv) Atom is the smallest particle which takes part in chemical reactions.