Atomic Structure

Question 1

Bohr’s model can explain (1985, 1M)
(a) the spectrum of hydrogen atom only
(b) spectrum of an atom or ion containing one electron only
(c) the spectrum of hydrogen molecule
(d) the solar spectrum

Answer 1

Option (B)

Question 2

What are Isotones?

Answer 2

These are the species in which both atomic number and mass number but number of neutrons are same

Question 3

What are Isotopes?

Answer 3

These are the atoms that have same atomic
number ( ) Z but different mass number ( ). A
e.g. 1
1 H , 1
2 H , 1
3 H are three isotopes of hydrogen.

Question 4

What are isobars?

Answer 4

These are the atoms of different elements
that have same mass number (A) but different atomic
number.
e.g. 18 Ar 40 ,
19
K 40.

Question 5

What is isoelectronic?

Answer 5

These species have same number of
electrons.

Question 6

What is Isodiapher?

Answer 6

These species have same isotopic
number, which is obtained by subtracting double of
atomic number from atomic mass (or mass number),
i.e. isotopic number
= mass number - ´ 2 atomic number.
e.g. 19
K and
39
9
F are isodiaphers.
19

Question 7

What is Planck’s Quantum Theory

Answer 7

In 1900, Max Planck provided an explanation to this
behaviour, according to which
• atoms and molecules could emit or absorb energy in
discrete quantities or packets only, which are called
quantum.
• the energy of a quantum is proportional to its frequency
as E h = n. where, h is the proportionality constant, called the
Planck’s constant with the value 6.626 10 Js. 34 ´
-
• energy is always gained or lost in integral multiples of
hn as 2hn, 3hn etc. In other words, energy is quantised.
Planck was unable to explain the reason behind
quantisation of energy. However, Einstein explained
the quantised nature of light while explaining the
phenomenon of photoelectric effect.