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unit 3, lesson 1 & 2
Term | Definition |
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atom | the smallest unit of an element that maintains the properties of that element |
electron | a subatomic particle that has a negative charge |
nucleus | in physical science, an atom's central region, which is made up of protons and neutrons |
proton | a subatomic particle that has a positive charge and that is located in the nucleus of an atom; the number of protons in the nucleus is the atomic number, which determines the identity of an element |
neutron | a subatomic particle that has no charge and that is located in the nucleus of an atom |
electron cloud | a region around the nucleus of an atom where electrons are likely to be found |
atomic number | the number of protons in the nucleus of an atom; the atomic number is the same for all atoms of an element |
mass number | the sum of the numbers of protons and neutrons in the nucleus of an atom |
periodic table | an arrangement of the elements in order of their atomic numbers such that elements with similar properties that fall in the same column, or group |
chemical symbol | a one-, two-, or three-letter abbreviation of the name of an element |
average atomic mass | the weighted average of the masses of all naturally occurring isotopes of an element |
metal | an element that is shiny and that conducts heat and electricity well |
nonmetal | an element that conducts heat and electricity poorly |
metalloid | an element that has properties of both metals and nonmetals |
group | a vertical column of elements in the periodic table; elements in a group share chemical properties |
period | in chemistry; a horizontal row of elements in the periodic table |