Question

What do you understand by isoelectronic species? Name a species that will be isoelectronic with each of the following atoms or ions. (i) F– (ii) Ar (iii) Mg2+ (iv) Rb+

Answer 1

elements having same or equal number of electrons are called  isoelectronic species
 1 na⁺ ion ,o²⁻ ion
2 cl⁻ ion,s²⁻ ion,k⁺ ion
3 o²⁻ ion,f ⁻ ion,al³⁺ ion
4 Br⁻ ion,Sr⁺ ion

Answer 2

Explanation:

Species that contain same number of electrons either in their ground state or ionic state are known as isoelectronic species.

• As atomic number of F is 9 and $F^{-}$ ion has 10 electrons. Neon atom in its ground state also has 10 electrons.

• Ar atom has atomic number 18 and it also contains 18 electrons. It is isoelectronic with $Ca^{2+}$ ion.

• $Mg^{2+}$ contains 10 electrons. This is also isoelectronic with $Na^{+}$ ion.

• $Rb^{+}$ has 36 electrons as in ground state the atomic number of rubidium is 37. It is isoelectronic with neutral atom of krypton (Kr).