Untitled

Page 1

Atoms and elements The periodic table

ontains protons and electrons

protons are positively charged

neutrons have no charge

nucleus has a positive charge overall because of protons

tiny compared to the rest of the atom

Electrons

move around nucleus

negatively charged

tiny, but cover a ot of space

occupy shells around nucleus

Number of protons= number of electrons

If some electrons are added or removed, the atom becomes

charged and is then an ion.

If a substance contains only one atom it is an element