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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