| A | B |
|---|
| medeleev | organized elements according to atomic mass, but was wrong how they were placed |
| period | horizontal row in periodic table |
| group | vertical column in peridoc table |
| metal | an element that is good conductor of electricity, groups 1-12 and some in 13 and 16 |
| transition metals | gtoups 3-12. not as reactive as group 1 and 2 and varied properties |
| nonmetal | an element that is poor condutor of electricity, group all 17 and 17 some in 14 and 16 |
| semiconductors or metaloids | a crystalline material with intermdeiate electrical conducticity, better conuctor but not as well as metals |
| main group elements | groups in 1,2,13 through 18. |
| alkali metals | highly reactive metallic elements in group1 that react rapidly with water to form hydrogen and alkaline solutions and that burn in air |
| alkaline-earth metals | reactive metallic elements in group2 with 2 electrons in the outermost energy level |
| lathanides | shiny, metallic transition metals with atomic numers 58 through 71 in which electrons are 4f orbitals |
| actinides | shiny , metallic transition metals with atomc numbers 90 through 103 in which electrons ore added to 5f orbitals |
| halogen | group 17, 7 electrosn on outer most. combined to make salts |
| salts | compound composed of +and - ions arraged in a regular 3 dimesional pattern |
| noble gases | elements in group 18 or periodic table that are chracterized by low reactivity |
| cation | positive charge |
| ion | negative charge |
| crystal | substance in which the atoms or molecules are arranged in an orderly, geometric, repeating pattern |
| conductive band | a band within whic electrons must move to allow electrical cunduction |
