| A | B |
|---|
| atom | the smallest particle in an element |
| electrons | negatively charged particles found moving rapidly in the elrectron cloud |
| nucleus | central core of an atom; consists of protons and neutrons |
| protons | positively charged particles in the nucleus of an atom |
| energy level | specific amount of energy that an electron has |
| neutron | small particle in the nucleus of an atom, with no electrical charge |
| atomic number | unique number of protons in the nucleus of an atom which identifies an element |
| isotopes | atoms with the same number of protons and a different number of neutrons |
| mass number | sum of protons and neutrons in the nucleus of an atom |
| atomic mass | average mass of all the isotopes of an element |
| periodic table | chart of elementss showing the repeating pattern of their properties |
| periods | horizontal row of elements in the periodic table |
| groups | elements in the same vertical column of the periodic table: also called a family |
| chemical symbol | one or two letter representation of an element |
| plasma | state of matter that consists of a gas like mixture of free electrons and nuclei of atoms that have been stripped of electrons |
| nuclear fusion | process in which two atomic nuclei combine, forming a larger nucleus and releasing huge amounts of energy |
