| A | B |
|---|
| proton | a positively charged particle |
| neutron | a particle with no charge |
| electron | a negatively charged particle |
| orbit | where electrons are located |
| nucleus | area of an atom that contains the neutrons and the protons |
| atomic number | equal to the number of protons |
| neutral atom | an atom where the number of protons equals the number of electrons |
| atomic mass | the mass of the protons and neutrons combined |
| ion | an atom where the protons and electrons are not equal |
| chemical symbol | an abbreviated way to write an element's name |
| period | a row on the periodic table of elements |
| group | a column on the periodic table of elements |
| noble gases | elements found in group 18 on the periodic table |
| halogens | elements found in group 17 on the periodic table |
| alkali metals | elements found in group 1 on the periodic table |
| alkaline earth metals | element found in group 2 on the periodic table |
| transition metals | elements found in groups 3 - 12 on the periodic table |
| metalloids | elements found along the zig zag line on the periodic table |
