# An atom loses electrons to form what?

Oct 17, 2016

An atom loses an electron to form $\text{a cation}$.

#### Explanation:

An atom loses electrons to form $\text{a cation}$, that is a positively charged ion (and one that is attracted towards the negatively charged terminal, the $\text{cathode}$).

${\text{Atom"+Deltararr"Atom}}^{+} + {e}^{-}$

Both charge and mass have been conserved. We had to put energy into the equation because the separation of unlike electric charges undoubtedly consumes energy.

Chemists measure this so-called ionization energy in the gas phase, and thus probe electronic, and atomic structure. The ionization energy is known to increase across a $\text{Period}$ of the Periodic Table (as we look at the Table from left to right), and DECREASE down a $\text{Group}$.