Transcript Chapter 20--Section 3

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