Question

From the symbol ${}_{15}^{31}\text{P}$, state:
(i) mass number of phosphorus,
(ii) atomic number of phosphorus, and
(iii) electron configuration of phosphorus.

Answer 1

An element along with its atomic number and mass number is represented as $X_z^A$

where X is the symbol of the element, Z is the atomic number and A is the mass number.

Therefore, in $P_{15}^{31}$

(i) Mass number: 31

(ii) Atomic number: 15

(iii) Electronic configuration : (2, 8, 5), that is K:2 L:8 M:5

$1s^2,2s^2,2p^6,3s^2,3p^3$