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atoms and periodic
unit 3, lesson 1,2
Term | Definition |
---|---|
atom | the smallest particle into which an element can be divided and still be the same element |
electrons | the negatively charged particles |
nucleus | a small, dense center that has positive charge and is surrounded by moving electrons |
protons | the positively charged particle |
neutrons | the nucleus contains uncharged particles |
electron cloud | the current theory, electrons don't move within an area around the nucleus |
atomic number | the number of protons in the nucleus of an atoms |
mass number | the total number of protons and neutrons in an atom's nucleus |
periodic table | arrangement of elements |
chemical symbol | an abbreviation for the elements name |
average atomic mass | an atom is the weight average of the masses of all the naturally occurring isotopes of that elements |
metals | elements that are shiny and conduct heat and electricity well |
nonmetals | poor conductors of heat and electricity |
metalloids | elements that have the same properties are often dull and brittle |
group | a vertical column of elements on the periodic table |
period | a horizontal row of elements on the periodic tble |