| A | B |
|---|
| electrons | negatively charged particles found in clouds outside the nucleus |
| protons | positively charged particles in the nucleus |
| neutrons | particles in the nucleus with a neutral charge |
| nucleus | the positively charged center of the atom made up of protons and neutrons |
| atomic mass unit | the mass of one proton or neutron |
| ion | an atom with more/less electrons than protons which give it a positive/negative charge |
| atomic number | the number of protons in the nucleus |
| isotope | a different variety of the same element in which the number of neutrons differ |
| mass number (atomic weight) | the sum of protons and neutrons in an atom |
| isotope names | based on the element name followed by the mass number |
| determining number of neutrons | subtract the atomic number from the mass number |
| atomic mass | the average of the masses of all the isotopes |
| gravitational force | depends on the masses of objects and the distance that separates them |
| electromagnetic force | like charges repel while opposite charges attract |
| strong force | a force strong enough to overcome the electromagnetic force |
| weak force | plays a key role in radioactive atoms |
