If a species has 11 protons, 12 neutrons and 10 electrons then:

(A) what is its atomic number and mass number?

(B) is it neutral, a cation or an anion? Explain.

(C) write its electronic configuration.

(D) name the species.

Given that the species has 11 protons, 12 neutrons and 10 electrons.
(A) The atomic number is equal to the number of protons. Therefore, the atomic number is 11.

$$\begin{aligned} \text{Mass number} &= \text{Number of protons} \\ &\quad + \text{Number of neutrons} \\ &= 11 + 12 = 23 \end{aligned}$$

So, the mass number is 23.

(B) The number of protons (11) is greater than the number of electrons (10).

Positive charge = +11

Negative charge = -10

Net charge = +11 - 10 = +1

Hence, the species has a positive charge of +1. Thus, it is a cation.

(C) According to the Bohr-Burry scheme: Maximum number of electrons in a shell = 2n$^{2}$

For K-shell, n = 1

So, K-shell can hold maximum 2 electrons.

For L-shell, n = 2

So, L-shell can hold maximum 2 × (2)$^{2}$ = 8 electrons.

Therefore, the electronic configuration of given species is 2, 8.

(D) The species is sodium ion (Na$^{+}$) because the atomic number 11 corresponds to sodium.