| A | B |
|---|
| atom | basic unit of matter |
| proton | positive charge, 1amu, in nucleus |
| electron | negative charge, 0 amu, in energy levels |
| neutron | no charge, 1 amu, in nucleus |
| nucleus | formed by strong forces that hold protons and neutrons in center of atom |
| isotopes | atoms of same elements with different masses |
| compound | pure substance formed of two or more elements chemically combined in definite proportions |
| element | pure substance formed of only one kind of atom |
| ionic bond | atoms combine by tranferring electrons |
| covalent bond | atoms combine by sharing electrons |
| molecule | smallest particle of a compound |
