| A | B |
|---|
| atomic number | number of protons in an atoms nucleus |
| average atomic mass | average mass of an element is the average mass of the mixture of its isotopes |
| chemical symbol | shorthand way to write chemical element |
| dot diagram | represents electrons in the outer energy level of an atom |
| electron | neg. charged particles that move around the nucleus |
| electron cloud | region where electrons are found |
| group | each of the 18 vertical columns of elements in the periodic table |
| isotope | atoms of the same elemet w/dif numbers of neutrons |
| mass number | sum of the protons and neutrons in a nucleus |
| metal | elements having shiny, good conductors of heat and electricity, are solids at room temps. |
| metalloid | elements having both properties of metals and nonmetals |
| nonmetal | usually gases or brittle solids at room temps. |
| nucleus | positively charged center of an atom that contains protons and neutrons |
| neutron | atomic particle w/no energy that is part of an atom's nucleus |
| period | horizontal row in the periodic table |
| periodic table | table of the elements arranged according to repeated changes in properties |
| proton | atomic particle w/a positive charge |
| quark | very small particles of matter that make up protons and neutrons |
