Chapter 20--Section 3 Mixed Groups

Diatomic Elements These elements exist naturally as diatomic elements: Hydrogen (H-2) Iodine (I-2) Nitrogen (N-2) Chlorine (Cl-2) Fluorine (F-2) Bromine (Br-2) Oxygen (O-2) Acronym: Have No Fear of Ice Cold Beverages

Properties of Metalloids can form from ionic and covalent bonds w/other elements can have metallic and nonmetallic properties some can conduct electricity better than most nonmetals, but not as well as metals—semiconductors w/exception of aluminum, all are located on the stair-step line

The Boron Group Group 13—have 3 valence electrons Boron—metalloid—common in some household products—borax, boric acid Aluminum—the most abundant metal in Earth’s crust Used in soft-drink cans, foil wrap, cooking pans, siding

The Carbon Group Allotropes—different forms of the same element that have different molecular structures (Silicon occurs as an allotrope_ Carbon—nonmetal, silicon and germanium are metalloids and tin and lead are metals Carbon occurs as an element in coal and as a compound in oil, natural gas and foods Si—abundant in Earth’s crust, found in sand, and almost all rocks and soil

Allotropes of Carbon Diamond—clear and extremely hard Has one carbon atom bonded to four other carbon atoms at vertices/makes it very strong Graphite—black powder—consists of hexagonal layers of carbons/ea carbon atom is bonded to three other carbon atoms Buckminsterfullerene—a new allotrope of carbon—buckyball—soccer-ball shaped

The Nitrogen Group Nitrogen family—Group 15 Elements tend to share electrons and form covalent compounds Ex: ammonia, fertilizer, nitrates, Phosphorous—in compound form is used for water softeners, fertilizers, match heads, china, etc. Antimony and Bismuth—used with other metals to lower their melting points

The Oxygen Group Group 16 Oxygen—exists in air as a diatomic molecule All living things require oxygen to survive Also ozone—protects us from Sun’s radiation Sulfur—nonmetal—exists in several allotropic forms—used as pigments in paints

Synthetic Elements Scientists break apart elements in order to make new SYNTHETIC elements (they smash existing elements with particles accelerated in a heavy ion accelerator) Except for technetium and promethium, each synthetic element has more than 92 protons (SEE MORE INFO-PG. 627)

Transuranium elements -have an atomic number of 92 or greater, the atomic number of uranium They do not belong exclusively to the metal, nonmetal, or metalloid group All are synthetic and unstable, and many disintegrate quickly ELEMENTS—pg. 628 Why make elements? New types of elements may be useful in medicine, or in other ways