| A | B |
|---|
| CHEMICAL SYMBOL | abbreviated way to write name of an element |
| NUCLEUS | center of an atom with a positive charge |
| ELECTRON | surrounds the nucleus of an atom and has a negative charge and very small mass |
| ATOM | the smallest part of matter |
| PROTON | part of the nucleus with a positive charge |
| NEUTRON | part of the nucleus with no charge (it is neutral) |
| ATOMIC NUMBER | number of protons in the nucleus of an atom |
| ELECTRON CLOUD | a cloud that surrounds the nucleus of an atom where an electron is likely to be |
| QUARKS | smaller particles of protons and neutrons |
| MASS NUMBER | sum of protons and neutrons in the nucleus of an atom |
| ISOTOPE | atoms of the same element with different number of neutrons |
| AVERAGE ATOMIC MASS | average mass of the mixture of an element's isotopes |
| ATOMIC MASS UNIT | unit of measurement of small masses of atoms |
| PERIODIC TABLE | arrangement of elements and their atomic masses |
| MENDELEEV | Russian chemist in 1800s organized elements into a periodic table |
| DOT DIAGRAM | uses symbol of the element and dots to represent electrons in the outer energy level |
| PERIOD | horizontal rows of the elements in the periodic table |
| METAL | most exist as solids, are shiny and good conductors of electricity |
| NONMETAL | most are gases or brittle solids such as oxygen, nitrogen and carbon |
| METALLOID | both metals and nonmetals such as boron and silicon |
| TRANSITION ELEMENTS | are metals but have properties not found in elements of other groups such as copper and iron |
