| A | B |
|---|
| atoms | the smallest particles of matter |
| atomic theory | matter is made up of fundamental particles |
| law of definite proportions | the principle that the elements that comprise a compound are always in a certain porportion by mass |
| hypothesis | a testable prediction to explain their observations |
| theory | an explanation based on many observations and supported by the results of many experiments |
| scientific law | simply a fact of nature that is observed so often that it becomes accepted as truth |
| electrons | negatively charged particles |
| protons | positively charged particles |
| isotopes | atoms of an element that are chemically alike, but differ in mass |
| neutron | neutral particle |
| nucleus | small, dense, positively charged central core |
| atomic number | is the # of protons in the nucleus of an atom of that element |
| mass number | sum of protons and neutrons in the nucleus |
| electromagnetic spectrum | the whole range of electromagnetic radiation |
| emission spectrum | spectrum of light released from excited atoms of an element |
| energy levels | regions of space in which electrons can move about the nucleus |
| electron cloud | space around the nucleus of an atom where the atom's electrons are found |
| valence electrons | electrons in the outermost energy level |
| lewis dot diagrams | illustrates valence electrons as dots around the chemical symbol of an element |
