Transcript Physical Properties of Nonmetals

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