Question

Name

(a) An alkali metal in period 3 and halogen in period 2.

(b) The noble gas with 3 shells.

(c) The non-metals present in period 2 and metals in period 3.

(d) The element of period 3 with valency 4.

(e) The elements i period 3 which does not form oxide.

(f) The element of lower nuclear charge out of Be and Mg.

(g) Which has higher E.A., Fluorine or Neon.

(h) Which has maximum metallic character Na, Li or K.

Answer 1

a)
An alkali metal in period 3 is sodium.

Halogen in period 2 is Fluorine.
b)
Argon has three shells. It is a noble gas with completely filled three shells (K,L and M shell ).
Atomic Number of Argon is 18.
Thus the electronic configuration is 2,8,8.
It has 2 electrons in K shell , 8 electrons in L shell and 8 electrons in M shell.
c)
Any element which has a tendency to lose electron behave as a metal. For example Sodium, Potassium , calcium etc all are metals . Specifically the elements in period 3 which act as metals are Sodium , Magnesium and Aluminium.
On the other hand elements which have a tendency to gain electrons acts as non-metals. For example, Chlorine , Bromine, Oxygen, Sulphur etc are non-metals . In period 2 boron , carbon , nitrogen, oxygen ad fluorine all are non-metals.
d)


Answer is Silicon .Its atomic number is 14.
The electronic configuration is 2,8,4 . It requires 4 electrons to complete its octet thus it show a valency of 4
e)

Argon is the element of period 3 which cannot form oxides
f)

The nuclear charge increases as we go down the group as it is equal to the number of protons in a nucleus. So the element of lower nuclear charge will be Be.
g)
neon
h)Maximum metallic character - Potassium