Core electrons

Definition

Core electrons are the electrons in an atom that are not involved in chemical bonding. They reside in the inner shells of an atom, closer to the nucleus.

5 Must Know Facts For Your Next Test

1. Core electrons do not participate in chemical reactions; valence electrons do.
2. The number of core electrons can be determined by subtracting the number of valence electrons from the total number of electrons in an atom.
3. Core electrons effectively shield outer (valence) electrons from the full attraction of the nucleus, a concept known as shielding or screening effect.
4. In electron configurations, core electrons are represented by filled inner orbitals, often abbreviated using noble gas notation.
5. The energy levels of core electrons are much lower (more negative) than those of valence electrons.

Review Questions

Related terms

Valence Electrons:

Electrons located in the outermost shell of an atom that can participate in chemical bonding.

Electron Configuration:

The distribution of electrons among the various atomic orbitals; it includes both core and valence electrons.

Shielding Effect:

The phenomenon where core electrons reduce the effective nuclear charge felt by valence electrons.