| Question | Answer |
| proton | a positively charged paritcle located in an atom's nucleus |
| neutron | a particle that has no electric charge and is located in an atom's nucleus |
| nucleus | the central region of an atom where most of the atom's mass is found in protons and neutrons |
| electrons | a negatively charged particle located outside an atom's nucleus |
| atomic number | the number of protons in the nucleus of an atom |
| atomic mass number | the total number of protons and neutrons in an atom's nucleus |
| isotope | an atom of one element that has a different number of neutrons than another atom of the same element |
| ion | an atom or group of atoms that has a positive or negative electric charge |
| atomic mass | the average mass of the atoms of an element |
| periodic table | a table of the elements, arranged by atomic number, that shows patterns in their properties |
| group | a vertical column in the periodic table of the elements. they have similar properties |
| period | a horizontal row in the periodic table of the elements. they have varying properties |
| reactive | likely to undergo a chemical change |
| metals | an element that tends to be shiny, easily shaped, and a good conductor of electricity and heat |
| nonmetals | an element that is not a metal and has properties generally opposite to those of a metal |
| metalloids | an element that has properties of both metals and nonmetals |
| radioactivity | the process by which the nucleus of an atom of an element releases energy and particles |
| half-life | the length of time it takes for half of the atoms in a sample of a radioactive element to decay into atoms of another element |
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Ch.18 LTI-MA 509
