Answer the following question given this paragraph: 

In ordinary chemical reactions, the nucleus of each atom (and thus the identity of the element) remains unchanged. Electrons, however, can be added to atoms by transfer from other atoms, lost by transfer to other atoms, or shared with other atoms. The transfer and sharing of electrons among atoms govern the chemistry of the elements. During the formation of some compounds, atoms gain or lose electrons, and form electrically charged particles called ions (Figure 2.28).


Q: When atoms gain or lose electrons, they can form electrically charged particles called what?

 Choices:

- crystals

- eons

- toxins

- ions

A:
ions
