| A | B |
|---|
| electrons | atomimc particles that have little mass and a negative charge |
| nucleus | the dense, central portion of the atom |
| protons | positively charged atomic particles found in the nucleus |
| neutrons | particles found in the nucleus and have a neutral charge |
| atomic number | the number of protons an atom has |
| mass number | equal to the total umber of neutrons and protons |
| isotopes | atoms of the same element but have different number of neutrons |
| orbitals | regions around an atom where electrons are likely to be found |
| electromagnetic spectrum | the range of wavelengths varying in frequency and wavelength |
| ground state | the state of an electron in which it has the lowest possible energy |
| excited state | the stat of an electron where it gains energy |
| quantum numbers | numbers that define the region in which electrons can be found |
| electron configuration | the arrangement of electrons in an atom |
