| A | B |
|---|
| atom | A tiny particle contained within all matter |
| element | a substance that is made of one kind of atom |
| proton | positvely charged subatomic particle |
| neutron | a neutral charged subatomic particle |
| electron | negatively charged subatomic particle |
| Niels Bohr | proposed that electrons orbited a postively charged nucleus |
| John Dalton | proposed that matter was composed of tiny particles called atoms |
| mass number | equal to the number of protons and neutrons within an atom |
| atomic number | equal to the number of protons within an atom |
| isotope | an atom that contains different number of neutons |
| compound | contains more than one kind of element |
| covalent bonding | atoms combine by sharing electrons |
| ionic bonding | atoms combine by bonding either negatively or positively |
| ion | an electrically charged atom |
| mixture | composed of two or more substances that are not chemically combined |
| heterogeneous mixture | a mixture that is not mixed evenly and contains own properties |
| homogeneous mixture | a mixture that is evenly mixed thoroughly |
