Question

1. Name the neutral element(s) in the fourth period of the periodic table which has: a) 7 valence electrons (name two elements)

b) [Ar] 4s23d104p2 configuration

c) the alkaline earth metal

d) the largest atomic radius

e) the halogen

f) diamagnetic electron configurations (name all elements)

Answer 1

(a) Manganese (Mn) has 7 valence electrons.
The electronic configuration of manganese is

[Ar] 3d5 4s2.

It has 25 electrons out of which 7 electrons are in the last shell or orbit.

Bromine (Br) has 7 valence electrons.

The electronic configuration of Br is

[Ar] 3d10 4s2 4p5

(b) The electronic configuration of Germanium (Ge) is

[Ar] 3d10 4s2 4p2

(c) Since alkaline earth metals are present in group 2 of the periodic table, In period 4 Calcium (Ca) is the alkaline earth metal.

(d) Since atomic radius decreases across the period from left to right, Potassium (K) has the largest atomic radius.

(e) Bromine is the halogen of period 4 of the periodic table.

(f) Elements having diamagnetic electronic configuration are

Ca : [Ar] 4s2

Ti : [Ar] 3d2 4s2

Fe : [Ar] 3d6 4s2

Ni : [Ar] 3d8 4s2

Zn : [Ar] 3d¹⁰4s²

Ge : [Ar] 3d10 4s2 4p2

Se : [Ar] 3d10 4s2 4p4

Kr : [Ar] 3d¹⁰ 4s² 4p⁶