Isoelectronic

Isoelectronic

When an atom, radical, or ion has an equal number of electrons or has the same number of electrons when compared to the atoms of another element, the two species are called isoelectronic.

Basically, if two atoms/ions/radicals have the same number of electrons they are isoelectronic to each other.

Examples:

Sodium is isoelectronic to neon when it loses one electron

When Na⁺=[He]2s²2p⁶ it is isoelectronic to Ne=[He]2s²2p⁶

Chlorine is isoelectronic to argon when it gains an electron

When Cl^-=[Ne]3s²3p⁶ it is isoelectronic to Ar=[Ne]3s²3p⁶

Further Information:

See atom, iso, electronic, electron and electronic configuration.