Question

Q. Name the element which has :
(a) the electronic configuration 2, 8, 1.
(b) a total of two shells, with 4 electrons in the valence shell.
(c) a total of three shells, with 3 electrons in the valence shell.​

Answer 1

Answer:

a) Sodiun (Na)

b) Silicon(Si)

c) Aluminum (Al)

Answer 2

An element can be identified by the electronic configuration.

Explanation:

1. 2, 8, 1

The electronic configuration of 2,8,1 is $1s^2 2s^2 2p^6 3s1$, which is identical to that of the Sodium element.

2. a total of two shells, with 4 electrons in the valence shell.

The electronic configuration can be written as $1s^2 2s^2 2p^2$, which is similar to that of Carbon.

3. a total of three shells, with 3 electrons in the valence shell.​

The electronic configuration can be written as $1s^22s^22p^63s^13p^1$ which is similar to that of Aluminium.