| A | B |
|---|
| periodic Table | an arrangement of elements by atomic number |
| Mendeleev | he designed a periodic table where elements were arranged in order of increasing atomic mass |
| Periodic Law | the physical and chemical properties of the elements are periodic functions of their atomic numbers (the properties repeat across the periodic table) |
| Period | each horizontal row of elements |
| Family or group | column of elements in the periodic table |
| Alkali metal | member of Family 1 (or 1A) that have a 1 valence electron and are extremely reactive; from salts with family 17. |
| Alkaline earth metal | member of Family2 (or 2A) of the periodic table that have 2 valence electrons |
| Transition metals | Families 3-12 (or the "B" family 1-9) of the periodic table; elements that have properties similar to other transition metals and to other metals but whose properties do not fit in with other families |
| Boron Family | Family 13 (or 3A) of the periodic table; elements have 3 valence electrons |
| Carbon Family | Family 14 (or 4A) of the periodic table; elements have 4 valence electrons |
| Nitrogen Family | Family 15 (or 5A) of the periodic table; elements have 5 valence electrons |
| Oxygen Family | Family 16 (or 6A) of the periodic table; elements have 6 valence electrons |
| Halogen Family | Family 17 (or 7A) of the periodic table; elements have 7 valence electrons and are highly reactive; form salts with family 1 |
| Noble gas family | Family 18 (or 8A) of the periodic table; elements have 8 valence electrons and are extremely un-reactive |
| Rare-earth elements | general term for any element in the lanthanoid or actinoid series |
| Lanthanoid series | first row of the rare-earth elements in periodic table; soft, malleable metals that have high luster and conductivity |
| Actinoid series | second row of the rare-earth elements on the periodic table; radioactive; all but 4 are man-made (synthetic) |
| Metals | elements that are good conductors of heat and electricity; they have luster (areshiny) ; have high melting points; are ductile and malleable; lose electrons to form compounds |
| Luster | shininess |
| Ductile | able to be drawn into a thin wire |
| Malleable | able to be hammered out into a thin sheet |
| Corrosion | gradual wearing away of a metal due to the chemical reaction in which the metal element changes into a metal compound |
| Non-metals | elements that are poor conductors of heat and electricity; have dull surfaces; have low melting points; are brittle; gains electrons when forming compounds |
| Metalloids | element that has properties of both metals and nonmetals |
| Valence electrons | electrons in the outermost energy level of an atom; responsible for how elements bond to make compounds |
| Chemical formula | combination of chemical symbols usually used to represent a compound |
| Atomic number | number of protons in the nucleus of an atom |
| Atomic mass or average atomic mass | the average of the masses of the existing isotopes of an element (sometimes referred to as the atomic weight) |
| Inert | nonreactive or un-reactive |
| Reactive | combines with other elements to form compounds |
