1) Atoms retain their identity during a chemical reaction.
2) All matter is composed of atoms.
3) Atoms combine in small, whole-numbered ratios.
4) All atoms of a given element are identical.
5) Different ratios of atoms produce different compounds.
6) J. J. Thomson suggested the “plum pudding” model of the atom.
7) Robert Millikan determined the charge on an electron.
8) The number of protons and neutrons in the nucleus of a given atom is called the atomic number.
9) Isotopes have different atomic number (Z) but the same mass number (A).
10) The vertical columns in the periodic table of the elements are called groups.
