1. Chapter 20--Section 3
Mixed Groups

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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)

10. 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