| A | B |
|---|
| atomic number | the number of protons in an atom's nucleus |
| mass number | the sum of the number of protons and neutrons in a particular atom's nucleus |
| average atomic mass | the average mass of the mixture of an element's isotopes |
| chemical symbol | a shorthand way to write the name of an element |
| electron | the negatively charged particle of an atom; moves around outside the nucleus |
| proton | the postively charged particle of an atom; found in the nucleus |
| neutron | the atomic particle which has no charge and is found in the nucleus |
| electron cloud | region surrounding the nucleus of an atom where its electrons are most probably found |
| isotope | atoms of the same element that have different numbers of neutrons |
| nucleus | the positively charged center of an atom that contains protons and neutrons |
| periodic table | a table of the elements arranged according to repeated changes in properties |
| group | a vertical row on the periodic table |
| family | another name for a group |
| period | a horizontal row on the periodic table |
| metal | elements to the left of the stair-step on the periodic table |
| nonmetal | elements to the right of the stair-step on the periodic table |
| metalloid | elements found along the stair-step on the periodic table and which have properties of both metals and nonmetals |
