| A | B |
|---|
| chemical symbol | shorthand way to write the name of an element |
| nucleus | center of the atom that contains the protons and neutrons |
| electron | negatively charged particles that move around the nucleus |
| proton | positively charged atomic particle found in the nucleus |
| neutron | atomic particle with no charge |
| atomic number | number of protons in an atom's nucleus |
| electron cloud | region where electrons are most probably found |
| quark | smaller particles that make up protons and neutrons |
| mass number | sum of the number of protons and neutrons in an atom's nucleus |
| isotope | atoms of the same element that have different numbers of neutrons |
| average atomic mass | the average mass of an element's mixture of isotopes |
| periodic table | table of the elements arranged according to repeated changes in properties |
| group | the vertical columns of the period table made up of elements sharing similar properties |
| dot diagram | diagram representing electrons in the outer energy level of an atom |
| period | horizontal row of the periodic table |
| metal | shiny, good conductors of heat and electricity |
| nonmetal | gases or brittle solids that do not conduct electricity or heat well |
| metalloid | elements having properties of both metals and nonmetals |
