| A | B |
|---|
| Mendeleev | found a pattern in the elements |
| periodic table | list of all the known elements |
| Henry Moseley | discovered protons |
| periodic table rows | called periods |
| periodic table columns | called families |
| atomic number | number of protons |
| atomic mass | particles in the nucleus |
| chemical symbol | used to write chemical formulas |
| metals | shiny, good conductors, malleable, ductile |
| classes of elements | metals, nonmetals, & metalloids |
| nonmetals | dull, poor conductors, brittle, unmalleable |
| metalloids | also called semiconductors |
| semiconductors | conduct electricity when light and temperature conditions are right |
| malleable | can be pounded on without breaking |
| ductile | can be stretched into thin wires |
| metals have _ | fewer valence electrons |
| nonmetals have _ | more valence electrons |
| metals are mostly _ | solids |
| nonmetals are mostly _ | gases |
| the periodic table is mostly | metals |
