| A | B |
|---|
| Nucleus | tiny central core of an atom. |
| Protons | have a positive electric charge. |
| Neutrons | have no charge. |
| Electrons | negative charge. |
| Valence electrons | farthest from nucleus, Involved in bonding. |
| Electron dot diagram | includes the symbol for an element surrounded by dots. Each dot equals one valence electron. |
| Atomic number | number of protons in the nucleus of an atom |
| Group | Number 1 - 18, identifies a group that an element belongs to in the periodic table. |
| Period | A row across the periodic table. |
| Covalent Bond | when two atoms share valence electrons and this makes the atoms more stable. Both atoms attract the two shared electrons at the same time. |
| Double bond | two pairs of electrons are shared between the oxygen atoms. |
| Molecular compound | molecules having covalently bonded atoms. Much weaker bond than ionic bonds. Most are poor conductors of electricity. |
| Polar | When the electrons are shared unequally in a covalent bond. |
| Nonpolar | when two atoms pull equally on the electons, neither atom becomes charged. |
| Mineral | natural, solid, crystal structure and a definite chemical composition. |
