Question

An atom has the electron configuration of 1s22s22p5 how many electrons are in that atom

Answer 1

Answer:

There are $9$ electrons in this atom.

Explanation:

Electron configuration of this atom: $1s^2\, 2s^2\, 2p^5$.

The electron orbitals of an atom are denoted as $1s$, $2s$, $2p$, $3s$, $3p$, etc. At any given time, an electron in this atom is located in exactly one orbital.

The electron configuration of an atom gives the number of electrons in each orbitals of this atom.

For example, in this atom, the superscript "$2$" on the right of "$1s$" means that there are two electrons in the $1s\!$ orbital of this atom. Hence, $1s^2\, 2s^2\, 2p^5$ would translate to:

• The $1s$ orbital of this atom contains $2$ electrons.
• The $2s$ orbital of this atom contains $2$ electrons.
• The $2p$ orbitals of this atom contain $5$ electrons.

Hence, there would be $2 + 2 + 5 = 9$ electrons in total in this atom.