| A | B |
|---|
| atom | the basic unit of matter |
| nucleus | the center of the atom made of protons and neutrons |
| electron | negatively charged particle with only 1/1840 the mass of the proton |
| proton | positively charged subatomic particle |
| neutron | a subatomic particle with no charge |
| element | a pure substance that consists entirely of one type of atom |
| isotopes | atoms of the same element that differ in the number of protons and neutrons |
| mass number | total number of protons and neutrons |
| compound | a substance formed by the chemical combination of two or more elements in definate proportions |
| ionic bond | formed when one or more electrons are transferred from one atom to the other |
| ions | positively and negatively charged atoms |
| covalent bond | atoms share electrons |
| molecule | structure that forms when atoms are joined by a covalent bond |
| van der Waals forces | weak intermolecular forces |
