Chapter 3: Elements
and the Periodic
Table
Section 4: Nonmetals and Metalloids
Nonmetal
• An element that lacks most of the properties of a metal.
• Most are poor conductors of electricity and heat and are
reactive with other elements. Solid nonmetals are dull and
brittle.
Physical Properties
• State
• 10 of 16 are gases at room temperature (O, N)
• Others are solids (C, I, S)
• 1 is liquid (Br)
• Solid nonmetals are generally opposite of metals
• Dull (not shiny)
• Brittle (not malleable or ductile): break or crumble if hit with
hammer
• Lower densities
• Poor conductors of heat and electricity
Chemical Properties
• Reactivity
• Most are reactive; readily form compounds
• Fluorine (F) is the most reactive known element
• Some, group 18, hardly ever form compounds
• Electrons during reactions with other atoms
• When nonmetals and metals react, electrons move from the metal
to the nonmetal (NaCl)
• When nonmetals form compounds with other nonmetals, they
share electrons and become bonded together into molecules (CH4)
Checkpoint 1
• What happens to the electrons in the atoms of nonmetals
when they form bonds with other atoms?
Checkpoint 1
• What happens to the electrons in the atoms of nonmetals
when they form bonds with other atoms?
• They either gain or share electrons.
Families of Nonmetals
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The Carbon Family
The Nitrogen Family
The Oxygen Family
The Halogen Family
The Noble Gases
Hydrogen
The Carbon Family
• Group 14
• Atoms can gain, lose, or share four electrons when reacting
with other elements
• Only carbon is a nonmetal
• Carbon has an important role in the chemistry of life and fossil
fuels
The Nitrogen Family
• Group 15
• Two nonmetals: nitrogen and phosphorus
• Usually gain or share three electrons when reacting with other
elements
• Nitrogen
• Makes up 80% of atmosphere
• Diatomic molecule: consists of two atoms
• Nitrogen fixation by bacteria that turn it into useful form for
plants
• Phosphorus
• Much more reactive, always found in compounds in nature
• Used to make matches
The Oxygen Family
• Group 16
• Contains three nonmetals: oxygen, sulfur, and selenium
• Usually gain or share two electrons when reacting with other
elements
• Oxygen
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•
•
•
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Important to life
Diatomic (oxygen you breathe) O2
Sometimes triatomic (ozone) O3
Can combine with almost every other element (very reactive)
Most abundant in Earth’s crust, second-most abundant in
atmosphere
• Sulfur
• Smells like rotten eggs
• Used to make rubber, sulfuric acid
Checkpoint 2
• Which family of elements gains or shares three electrons?
Checkpoint 2
• Which family of elements gains or shares three electrons?
• The Nitrogen family.
The Halogen Family
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Group 17
Fluorine (F), Chlorine (Cl)
Halogen: salt forming
All but astatine (At) are nonmetals
Typically gain or share one electron when they react with
other elements
• Very reactive; dangerous in uncombined form
• Fluorine (F) is most reactive, reacts with almost every known
substance
• Useful in compounds
• Ex. Fluorine compounds added to water supply to help prevent
tooth decay
The Noble Gases
• Group 18
• Do not ordinarily form compounds because atoms of noble
gases do not usually gain, lose, or share electrons (unreactive)
• Found in small amounts in Earth’s atmosphere
• Not discovered until the late 1800s
Hydrogen
• Simplest and smallest atom: one proton and one electron
(some isotopes of hydrogen also have neutrons)
• Very different from other elements; not in a family 
(hydrogen is not an alkali metal, even though it’s in the same
column)
• Makes up more than 90% of the atoms in the universe, but
only 1% of the mass of Earth’s crust, oceans, and atmosphere
• Rarely found as a pure element; usually in water molecules
The Metalloids
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Have some characteristics of both metals and nonmetals
All are solid at room temperature
Brittle, hard, and somewhat reactive
Most useful property is their varying ability to conduct
electricity
• Conductivity depends on temperature, exposure to light, or the
presence of small amounts of impurities
• Used to make semiconductors (substances that can conduct
electricity under some conditions but not under other conditions)
in computer chips, transistors, and lasers.
• Most common is silicon (Si), which forms a compound with
oxygen to make sand and glass
Checkpoint 3
• Which family of nonmetals is unreactive?
Checkpoint 3
• Which family of nonmetals is unreactive?
• The noble gases.
Post-lesson Quiz
1. Which is not a property of nonmetals?
a. shininess
b. dullness
c. brittleness
d. poor conductivity
Post-lesson Quiz
2. Where are nonmetals generally located on the periodic table?
a. on the right side
b. in the middle
c. on the left side
d. interspersed throughout
Post-lesson Quiz
3. Some metalloids can conduct electricity under some
conditions, but not others. Because of this, these metalloids are
sometimes called…
a. pseudo-conductors
b. semiconductors
c. hemiconductors
d. biconductors
Post-lesson Quiz
4. Which element is the simplest and is not part of a family?
a. helium
b. lithium
c. boron
d. hydrogen
Post-lesson Quiz
5. What happens when nonmetal atoms form bonds with other
atoms?
a. they lose electrons
b. they always gain electrons
c. they sometimes gain and sometimes share electrons
d. they always share electrons