Sci9 Unit A Ch.2 Elements

3. It is equal to the number of protons and neutrons in an atom
7. The family of metals that are highly reactive and combine with halogens to form salts.
8. The set of elements that are lustrous, malleable, ductile, and good conductors.
9. A "type" of atom; a pure substance that cannot be broken down or separated into simpler substances.
10. The name of the last electron shell, which is responsible for the element's reactivity.
11. The group of elements that are dull, brittle, non-ductile, and poor conductors.

1. This number indicates the number of protons and electrons in an atom of an element.
2. A column of elements on the periodic table that have similar properties.
4. Each element is designated by a one- or two-letter _____.
5. The family of elements that contains a solid, a liquid, and a gas at room temperature and reacts very readily with metals and hydrogen.
6. The family of gases that are very unreactive because their valence shell is full.
7. The family of metals that are quite reactive, especially with water, and have two valence electrons.
8. The name of the scientist responsible for creating the periodic table.