| A | B |
|---|
| Chemical Symbol | A shorthand way to write the name of an element |
| Nucleus | The positively charged center of an atom |
| Electron | A negatively charged particle that orbits around the nucleus of an atom |
| Proton | A particle in the nucleus of an atom that has a positive charge |
| Neutron | A particle in the nucleus of an atom that has no electrical charge |
| Atomic Number | The number of protons in an atom's nucleus |
| Electron Cloud | The space where electrons most probably exist around the nucleus of an atom |
| Periodic Table | A table of the elements, in order by increasing atomic mass, arranged in rows and columns based on the number of valence electrons and therefore chemical properties |
| Group | One of the 18 vertical columns in the periodic table |
| Dot Diagram | A diagram of an atom, using the element symbol with dots to show the valence electrons (electrons in the outer energy level) |
| Period | A horizontal row of elements in the periodic table; increasing from left to right is the number of valence electrons |
| Metals | An element usually having the following characteristics: shiny, ductile, and a good conductor of heat and electricity |
| Nonmetal | An element that usually lacks the characteristics of a metal |
| Metalloid | An element having some properties of both a metal and a nonmetal |
| Alkali Metals | The metals in Group 1 of the periodic table |
| Alkaline Earth Metals | Metals in Group 2 of the Periodic Table |
| Halogens | Non-metals in Group 17 of the Periodic Table |
| Noble Gases | Gases in Group 18 of the Periodic Table |
| Valence electrons | Electrons in the outer energy level (shell) of an atom |
| Atomic Mass | Number of protons & neutrons in the nucleus (the number of particles in the nucleus) |
