1.
each horizontal line of elements in the periodic table
2.
when elements are in order of increasing atomic number there is a periodic repetition of their physical and chemical properties
3.
each vertical column of elements
4.
one half the distance between the nuclei of two atoms of the same element
5.
an atom or group of atoms that has a positive or negative charge
6.
an atom that loses one or more electrons to form an ion with a net positive charge
7.
an atom that gains one or more electrons to form an ion with a net negative charge
8.
the energy required to remove the outermost electron from the ground state of a gaseous atom
9.
the energy change that happens when an atom gains an electron
