Question

An ion ${\mathrm{M}}^{3+}$contains 10 electrons and 14 neutrons. What is the atomic number and mass number of the element $\mathrm{M}$? Name the element.

Answer 1

• Atom consists of three subatomic particles, they are protons, electrons, and neutrons.
• Protons are positively charged particles., electrons are negatively charged particles., and neutrons have no charge
• The number of protons in one atom of an element is called the atomic number of the element. It is represented by the symbol ‘Z’
• All the atoms of the same element have the same number of protons in their nuclei and hence they have the same atomic number (Z).
• No two elements have the same atomic number. Moreover, the number of protons in an atom is equal to the number of electrons.

Atomic number (Z) = number of protons in an atom = Number of electrons.

The mass number is defined as the sum of the number of protons and the number of neutrons.

Mass number (A) = Number of protons + number of neutrons.

The given ion M³⁺electronic configuration = 2,8

because M has donated 3 electrons so it has a positive charge of 3.

so For M the electronic configuration = 2,8,3

Number of electron = number of protons = 13 for M

Therefore atomic number = 13

Mass number for M = 13+14 = 27.

Hence the element is aluminium.