Term | Definition |
alkali metals | group 1 and most reactive metal on the periodic table |
alkaline earth metals | group 2 and is a valence electron |
group | a column on the periodic table |
metals | an element that is shiny, easily pulled into wires or hammered into thin sheets, and a good conductor of electricity and thermal energy |
period | a row on the periodic table |
transition elements | an element in groups 3-12 on the periodic table |
noble gases | least reactive gas and is in group 18 |
atom | a small particle that is the building block of matter, and is the smallest piece of an element that still represents that element |
atomic number | the number of protons in an atom of an element |
atomic mass | amount of mass in an object |
ion | an atom that is no longer neutral because it has lost or gained valence electrons |
neutron | a neutral particle in the nucleus of an atom |
average atomic mass | the average mass of the element's isotopes, and is weighted according to the abundance of each isotope |
iosotopes | atoms of the same element that have different numbers of neutrons |
nucleus | the region in the center of an atom where most of an atom's mass and positive charge are concentrated |
elements | a substance that consists of only one type of atom |
protons | positively charged particle in the nucleus of an atom |
radioactivity | any element that spontaneously emits radiation |
electrons | a negatively charged particle that occupies the space in an atom outside the nucleus |