Question

An element A has 2 electrons in its fourth shell. State it's (a) atomic number
(b) electronic configuration
(c) valency
(d) position in the periodic table
(e) is it a metal or non metal
(f ) is it an oxidizing or reducing agent

Answer 1

●element is calcium

◆atomic no. is 20

◆electronic configuration -2,8,8,2

◆valancy is 2

◆ belongs to period no.4 and group no. 2

◆it is metal.

Answer 2

Answer:

An element A has two electrons in its fourth shell, so it will appear as 4s²4p⁰. Therefore, the given element A is Calcium.

• (a) The atomic number of the given element A is 20.
• (b) The electronic configuration of calcium is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s².
• (c) The valency if an element is defined as the combining capacity, that how many number of hydrogens can combine with that element. The valency of calcium is 2.
• (d) The position of calcium in the modern periodic table is fourth period and group 2. In the fourth period, calcium is present after Potassium (K) and before Scandium (Sc).
• (e) Because calcium is present in group 2. All the elements of group 2 are alkaline earth metals. So, calcium is a alkaline earth metal.
• (f) Calcium is reducing agent. Calcium (Ca) is used as a reducing agent in preparation of  other metals such as thorium (Th) and uranium (U).