Nonmetals and Metalloids

What is a nonmetal? Elements that lack most of the properties of metals. Located to the right of the zigzag line in the periodic table. Very common elements Extremely important to all living things on Earth

Physical Properties Many are gases at room temperature Opposite to those that characterize the metals Dull Break apart or easily crumble into pieces. Poor conductors of heat and electricity

Chemical Properties Readily form compounds; however, group 18 rarely ever do

Compounds of Nonmetals When nonmetals and metals react – valence electrons move from the metal atom to the nonmetal atom. Na + Cl = NaCl Nonmetals can form compounds with other nonmetals too. Atoms share electrons Many even form molecules of two identical atoms – diatomic molecules (O₂ , N₂, H₂)

Families of Nonmetals Carbon Family Nitrogen Family Oxygen Family Halogen Family Noble Gases Hydrogen

Carbon Family Group 14 Each element has atoms with 4 valence electrons Only one element is a nonmetal – Carbon Two are metalloids – silicon and germanium Two are metals – tin and lead

Nitrogen Family Group 15 Contain 5 valence electrons Two nonmetals – nitrogen and phosphorus

Oxygen Family Group 16 Six valence electrons Three nonmetals – oxygen, sulfur, selenium The oxygen we read is a diatomic molecule Ozone is a triatomic molecule Oxygen is very reactive and can combine with almost any element.

Halogen Family Group 17 Fluorine, chlorine, bromine, iodine and astatine All are nonmetals except astatine 7 valence electrons All are very reactive, most are dangerous to humans

Noble Gases Group 18 Do not ordinarily form compounds with other elements Do not gain, lose or share their valence electrons Generally very stable and unreactive All exist in Earth’s atmosphere in small amounts

Hydrogen Hydrogen has chemical properties very different from other elements in family. Makes up more that 90% of the atoms in the universe 1% of mass of Earth’s crust, oceans, and atmosphere Rarely found on Earth as a pure element

Metalloids Have some of the characteristics of metals and some of nonmetals Seven metalloids Most common is silicon Most useful property is their varying ability to conduct electricity. Some are used to make semiconductors