Section 4: Nonmetals and Metalloids Objectives: locate nonmetals and metalloids in the periodic table compare the physical and chemical properties of nonmetals with those of metals, and describe the properties of metalloids

What is a Nonmetal? The element on the right side of the zigzag line are nonmetals. (yellow boxes) •An element that does not have most of the properties of metal.

Physical Properties of Nonmetals •low melting point -many are gases at room temperature

Few are solids at room temperature Examples: Sulfur, carbon, and iodine Only bromine is a liquid at room temperature. Most physical properties of nonmetals are opposite of the metals; -dull, not shiny -solid nonmetals are brittle (not malleable and not ductile) -poor conductors of heat and electricity.

Chemical Properties of Nonmetals Except for Group 18 most form compounds -able to gain or share electrons (usually do not loose electrons) -Group 18 has full valence shells do not easily loose or share electrons

Compound of Nonmetals Nonmetals usually react with metals Valence electrons move from the metal atoms to the nonmetals Example: table salt (NaCl) sodium has 1 valence electron and chlorine has 7 Nonmetals can form compounds with other nonmetals forms diatomic molecules such as oxygen and hydrogen

Families of Nonmetals Carbon is most important in chemistry of living things ·All living thing made up of carbon. Carbon only nonmetal is this family Silicon and germanium are metalloids Tin and lead are metal Contain 4 valence electron

Diamonds and soot are both forms of carbon. Diamonds are the hardest material materials. It is used as a jewel and for saws, drills, and files. Soot is very soft. It is used as pigment in paints and crayons

Nitrogen Group Contain 5 valence electrons 80% of atmosphere is nitrogen Most living things get nitrogen from food eaten Some bacteria use nitrogen from the air

Phosphorus is in nitrogen group Not stable as element Must combine with other elements to form compounds

Oxygen Group Elements in this group share or gain 2 Electrons Group contains 3 nonmetals Important gas for all living things Oxygen is most abundant element is Earth crust and 2nd most abundant element in earths atmosphere

Sulfur is nonmetal in oxygen family Used in production of rubber bands, tires, and medicines

Halogen Family All elements have 7 electron Usually gains or shares one electron All elements are nonmetals Very reactive Dangerous to humans in pure form

Halogens Fluorine used in nonstick cookware and fluoridation of water to fight tooth decay Chlorine is used as disinfectant found in table salt Bromine is used in compound of silver bromide that is used in photographic film. Iodine is used as disinfectant

Noble Gases Valence shell is full with 8 electrons Very stable and unreactive All are found in earth’s atmosphere in small amounts

Hydrogen Stands Apart 1 proton and 1 electron however chemical properties are so different it is not grouped into a family 90% of atoms in universe are hydrogen, but only 1% of mass of crust, oceans, and atmosphere is hydrogen Rarely found on earth as pure element

Metalloids Areas shaded in green are metalloids Have some characteristics of metals and some of nonmetals

Most useful property of metalloid is ability to conduct electricity Silicon and germanium are used to make semiconductor Semiconductors carry electricity under some conditions and during other conditions cannot carry electricity Used in computer chips, transistors, and lasers.