Question

Name the following elements 

(a) Two shells, both of which are completely filled. 

(b) Three shells with 2 valence electrons. 

(c) Group 1, two shells. 

(d) Group 17, period 3. 

(e) Metal, with valency 3 group number 13 period 3.

Answer 1

(a) Two shells → K L

Completely filled → 2,

8 Atomic number → 10

∴ Element — Neon.

(b) Three shells → K, L, M

2 Valence electron → 2, 8, 2

Atomic number → 12

∴ Element = Magnesium

(c) Group 1

2 shells → K L

Electronic (RBSESolutions.com) configuration → 2,1

Atomic number → 3

∴ Element = Lithium

(d) Group 17

Period → 3, K L M

Electronic configuration → 2, 8, 7

Atomic number → 17,

∴ Element = Chlorine

(e) Group → 13

Valency → 3

Period → 3 K L M

Electronic configuration → 2, 8, 3

∴ Atomic number → 13,

∴ Element = Aluminium.