Question

If an element has $15$ protons and $16$ neutrons in the nucleus, find out its atomic number and mass number. Represent the element with atomic and mass numbers.

Answer 1

Given:

Number of protons$=15$

Number of neutrons$=16$

Formula used:

1. Atomic number$=$Number of protons$=$Number of electrons
2. Mass number$=$Number of protons$+$Number of neutrons
3. Representation of atom$={}_{\mathrm{Z}}{}^{\mathrm{A}}\mathrm{X}$

Here, $\mathrm{X}$ is the chemical symbol of the element, $\mathrm{Z}$ is the atomic number and $\mathrm{A}$ is the mass number

Calculate the atomic number of the element:

Atomic number$=$Number of protons

Thus,

Atomic number$=15$

Thus, the atomic number of the element is $15$.

Calculate the mass number of the element:

Mass number$=$Number of protons$+$Number of neutrons

Thus,

Mass number$=15+16$

Mass number$=31$

Thus, the mass number of the element is $31$.

Represent the element:

The element with atomic number $15$ is Phosphorous $\mathbf{\left(}\mathbf{P}\mathbf{\right)}$.

The general representation of elements is done as ${}_{\mathrm{Z}}{}^{\mathrm{A}}\mathrm{X}$.

Substitute $\mathrm{P}$ for the chemical symbol, $15$ for the atomic number and $31$ for the mass number.

Thus, the representation of element is ${}_{15}{}^{31}\mathrm{P}$.