Topic
10
Table of Contents
Topic
10
Topic 10: Elements
Basic Concepts
Additional Concepts
Elements: Basic Concepts
Topic
10
Periodic Properties of the Elements
• An element’s chemical and physical
properties are closely related to its position in
the periodic table and that certain properties
repeat periodically.
• Both position in the periodic table and the
properties of the elements arise from the
electron configurations of their atoms.
Elements: Basic Concepts
Topic
10
Periodic Properties of the Elements
• Understanding the relationship between
electron configuration and position in the
periodic table enables you to predict the
properties of the elements and the outcome
of many chemical reactions.
Elements: Basic Concepts
Topic
10
Behavior of Main Group Elements
• Elements in the same group (vertical column)
of the periodic table have the same number of
valence electrons, and because of this, they
have similar properties.
• But elements in a period (horizontal row)
have properties different from one another.
Elements: Basic Concepts
Topic
10
Behavior of Main Group Elements
• This is because the number of valence
electrons increases from one to eight as you
move from left to right in any row of the
periodic table except the first.
• As a result, the character of the elements
changes.
Elements: Basic Concepts
Topic
10
Behavior of Main Group Elements
• Each period begins with two or more metallic
elements, which are followed by one or two
metalloids.
• The metalloids are followed by nonmetallic
elements, and every period ends with a noble
gas.
Elements: Basic Concepts
Topic
10
Trends in Metallic Properties
Elements: Basic Concepts
Topic
10
Patterns in Atomic Size
• Recall that the size of an atom increases in
any group of elements as you go down the
column because the valence electrons are
found in energy levels farther and farther
from the nucleus.
• But how does atomic radius change across a
period from left to right?
• The lithium atom, with only three electrons,
is actually larger than the fluorine atom,
which has nine.
Elements: Basic Concepts
Topic
10
Patterns in Atomic Size
• There’s a simple explanation for the trend of
decreasing atomic size across a period.
• Picture the valance electron on a lithium atom.
• The lithium nucleus has three protons, so
there’s an attractive force of 3+ acting on the
electron.
Elements: Basic Concepts
Topic
10
Patterns in Atomic Size
• Now, think about the valence electrons in a
beryllium atom.
• Here, there is an attractive force of 4+ from
the four protons in the beryllium nucleus.
Elements: Basic Concepts
Topic
10
Patterns in Atomic Size
• With each increase in nuclear charge across
the period, the outer electrons are attracted
more strongly toward the nucleus, resulting
in smaller size.
Elements: Basic Concepts
Topic
10
Atomic Radii of Main Group Elements
Elements: Basic Concepts
Topic
10
Ionic Size
• Atomic size is an important factor in the
chemical reactivity of an element.
• Ionic size is also important in determining
how ions behave in solution and the structure
of solid ionic compounds.
Elements: Basic Concepts
Topic
10
Ionic Size
• When metallic atoms lose one or more
electrons to become positive ions, they
acquire the configuration of the noble gas in
the preceding period.
• This means that the outermost electrons of
the ion are in a lower energy level than the
valence electrons of the neutral atom.
Elements: Basic Concepts
Topic
10
Size of Atoms and Their Ions
• The electrons that are not
lost by the atom experience
a greater attraction to the
nucleus and pull together in
a tighter bundle with a
smaller radius.
• The result is that all positive
ions have smaller radii than
their corresponding atoms.
Elements: Basic Concepts
Topic
10
Size of Atoms and Their Ions
• When an atom gains
electrons to become a
negative ion, the atom
acquires the electron
configuration of the noble
gas at the end of its period.
• But the nuclear charge
doesn’t increase with the
number of electrons.
Elements: Basic Concepts
Topic
10
Size of Atoms and Their Ions
• In the case of fluorine, a
nuclear charge of 9+ must
hold ten electrons in the
F– ion.
• The result is that all the
electrons are held less
tightly, and the radius of the
ion is larger than the neutral
atom.
Elements: Basic Concepts
Topic
10
Patterns in Ionic Radii― The Alkali
Metals
• The Group 1 elements—
lithium (Li), sodium (Na),
potassium (K), rubidium
(Rb), cesium (Cs), and
francium (Fr)—are called
the alkali metals. The
alkali elements are soft,
silvery-white metals and
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good conductors of heat
and electricity.
Elements: Basic Concepts
Topic
10
Patterns in Ionic Radii― The Alkali
Metals
• Their chemistry is relatively uncomplicated;
they lose their s valence electron and form a
1+ ion with the stable electron configuration
of the noble gas in the preceding period.
Elements: Basic Concepts
Topic
10
Patterns in Ionic Radii― The Alkaline
Earth Metals
• The Group 2 elements—beryllium (Be),
magnesium (Mg), calcium (Ca), strontium
(Sr), barium (Ba), and radium (Ra)—are
called the alkaline earth metals.
Elements: Basic Concepts
Topic
10
Patterns in Ionic Radii― The Alkaline
Earth Metals
• The properties of Group 2 elements are similar
to those of the Group 1 elements.
• Like the alkali metals, they are too reactive to
be found as free elements in nature.
• They lose both of their s valence electrons and
form 2+ ions with the stable electron
configuration of the noble gas in the preceding
period.
Elements: Basic Concepts
Topic
10
Important Properties of Magnesium
• Alloys of magnesium
are used where light
weight and strength
are important, as in
this jet engine.
• Magnesium resists corrosion because it reacts
with oxygen in the air to form a coating of
magnesium oxide.
• The coating of MgO protects the metal
underneath from further reaction with oxygen.
Elements: Basic Concepts
Topic
10
Strontium Reveals Its Presence
• Strontium is a less well-known element of
Group 2, but it’s important, nevertheless.
• Because of its chemical similarity to calcium,
strontium can replace calcium in the
hydroxyapatite of bones and form
Sr5(PO4)3OH.
Elements: Basic Concepts
Topic
10
Strontium Reveals Its Presence
• This could be a problem only if the strontium
atoms are the radioactive isotope strontium-90,
which is hazardous if it is incorporated into a
person’s bones.
Elements: Basic Concepts
Topic
10
Group 13 Elements
• Only boron, the first element in Group 13, is a
metalloid.
• The other Group 13 elements—aluminum (Al),
gallium (Ga), indium (In), and thallium (Tl)—
are metals.
Elements: Basic Concepts
Topic
10
Group 13 Elements
• None of the metals are as active as the metals
in Groups 1 and 2, but they’re good conductors
of heat and electricity.
Elements: Basic Concepts
Topic
10
The Uses of Group 13 Elements
• Boron is a metalloid found in boric acid
(H3BO3) and borax (Na2B4O7•10H2O).
• Boric acid is one of the active ingredients in
eyewash or contact lens-cleaning solution.
• Borax is the abrasive in some tough
cleansing powders.
• It’s also used as a water softener and is an
important component in some types of glass.
Elements: Basic Concepts
Topic
10
Group 14 Elements
• The Group 14 elements—carbon (C), silicon
(Si), germanium (Ge), tin (Sn), and lead
(Pb)—exhibit a variety of properties.
Elements: Basic Concepts
Topic
10
Group 14 Elements
• Carbon is a nonmetal, silicon and
germanium are metalloids, and tin and lead
are metals.
Elements: Basic Concepts
Topic
10
Group 15 Elements
• The trend in metallic properties is obvious
as you go from the top of Group 15 to the
bottom—from nitrogen (N) to phosphorus
(P) to arsenic (As) to antimony (Sb) and
bismuth (Bi).
• Nitrogen and
phosphorus
are nonmetals.
Elements: Basic Concepts
Topic
10
Group 15 Elements
• They form covalent bonds to complete their
outer-level configuration.
• Arsenic and antimony are metalloids and
either gain or share electrons to complete
their octets.
• Bismuth is more metallic and often loses
electrons.
Elements: Basic Concepts
Topic
10
Group 16 Elements
• The Group 16 elements—oxygen (O), sulfur
(S), selenium (Se), and tellurium (Te)—are
nonmetals, and polonium (Po) is a metalloid.
• Their valence-electron configuration is s2p4.
• With rare exceptions, oxygen gains two
electrons and forms the oxide ion (O2–) with
the neon configuration.
Elements: Basic Concepts
Topic
10
Group 16 Elements
• Oxygen reacts with both metals and nonmetals
and, among the nonmetals, is second only to
fluorine in chemical reactivity.
Elements: Basic Concepts
Topic
10
Group 17 Elements
• The halogens—fluorine (F), chlorine (Cl),
bromine (Br), idodine (I), and astatine
(At)—are active nonmetals.
• Because of their chemical reactivity, they
don’t exist as free elements in nature.
Elements: Basic Concepts
Topic
10
Group 17 Elements
• Their chemical behavior is characterized by
a tendency to gain one electron to complete
their s2p5 valence-electron configuration and
form a 1– ion with a noble-gas configuration.
Elements: Basic Concepts
Topic
10
Group 18 Elements
• Helium (He), neon (Ne), argon (Ar), krypton
(Kr), xenon (Xe), and radon (Rn), the noble
gases, were originally called the inert gases
because chemists couldn’t get them to react.
Elements: Basic Concepts
Topic
10
Properties of the Transition Elements
• With the exception of the Group 12 elements
(zinc, cadmium, and mercury), the transition
metals have higher melting points and boiling
points than those of almost all of the main
group elements.
Elements: Basic Concepts
Topic
10
Properties of the Transition Elements
• Multiple oxidation states are characteristic of
the transition elements.
• Many of the transition elements can have
multiple oxidation numbers ranging from
2+ to 7+.
Elements: Basic Concepts
Topic
10
Properties of the Transition Elements
• These oxidation numbers are due to
involvement of the d electrons in chemical
bonding.
Elements: Basic Concepts
Topic
10
Lanthanides and Actinides:
The Inner Transition Elements
• In the lanthanides, electrons of highest energy
are in the 4f sublevel.
• The lanthanides were
once called rare earth
elements because all of
these elements
occurred in Earth’s
crust as earths, an older term for oxides, and
seemed to be relatively rare.
Elements: Basic Concepts
Topic
10
Lanthanides and Actinides:
The Inner Transition Elements
• The
highestenergy
electrons
in the
actinides
are in the
5f
sublevel.
Basic Assessment Questions
Topic
10
Question 1
Explain why elements within the same group of
the periodic table are similar but not identical in
properties, such as ionization energy.
Basic Assessment Questions
Topic
10
Answer
Elements within the same group of the periodic
table have the same number of valence electrons,
but different numbers of nonvalence electrons.
Basic Assessment Questions
Topic
10
Question 2
Compare the alkali and alkaline earth metals
in terms of position in the periodic table,
number of valence electrons, and overall
properties.
Basic Assessment Questions
Topic
10
Answer
The alkali metals have one valence electron and
are in group 1A. The alkaline earth metals have
two valence electrons and are in group 2A. Both
types of metals are reactive, but the alkaline
earth metals are less reactive. The alkali metals
are softer.
Basic Assessment Questions
Topic
10
Question 3
Compare the metallic character of the
elements carbon, silicon, and lead. What do
these elements have in common in terms of
valance electrons and placement in the
periodic table?
Basic Assessment Questions
Topic
10
Answer
Carbon is a nonmetal, silicon is a metalloid, and
lead is a metal. All have four valence electrons
and are located in group 4A.
Elements: Additional Concepts
Topic
10
Additional Concepts
Elements: Additional Concepts
Topic
10
Reactivity of the Group 1A Element,
Lithium
• Lithium is the most active metal in the
second period because it can attain the noblegas configuration of helium by losing a single
electron.
• If lithium loses one electron from its 2s
sublevel, its electron configuration changes
from 1s22s1 to 1s2.
Elements: Additional Concepts
Topic
10
Reactivity of the Group 1A Element,
Lithium
• The resulting lithium ion has a 1+ charge and
the same electron configuration as a helium
atom.
• While this is not an octet, it is a noble-gas
configuration.
• Elements tend to react in ways that allow
them to achieve the configuration of the
nearest noble gas.
Elements: Additional Concepts
Topic
10
Reactivity of the Group 2A Element,
Beryllium
• Beryllium, the next element in the second
period, must lose a pair of 2s electrons to
acquire the helium configuration.
• It’s harder to lose two electrons than it is to
lose one, so beryllium is slightly less reactive
than lithium.
• Nevertheless, beryllium does react by losing
both of its 2s electrons and forming a 2+ ion
with the helium electron configuration.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 3A Element,
Boron
• If this pattern continued, you would expect
boron to lose three electrons to attain the
helium configuration.
• Sometimes, boron does react by losing
electrons, but often it reacts by sharing
electrons.
• Boron is the only metalloid in the period.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 3A Element,
Boron
• That means boron sometimes behaves like a
metal and loses electrons like its neighboring
metals, lithium and beryllium.
• When it loses electrons, boron achieves the
noble-gas configuration of helium.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 3A Element,
Boron
• But more often, boron acts like a nonmetal
and shares electrons.
• Boron is unusual because it has only three
electrons to share and cannot acquire an octet
of electrons by just sharing.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 4A, 5A, 6A,
and 7A Elements, C, N, O, and F
• Carbon, nitrogen, oxygen, and fluorine are
nonmetals.
• Carbon, with the configuration [He]2s22p2,
and nitrogen, with the configuration
[He]2s22p3, share electrons to attain the
noble-gas configuration of neon, [He]2s22p6.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 4A, 5A, 6A,
and 7A Elements, C, N, O, and F
• Oxygen, with the configuration [He]2s22p4,
gains two electrons to form the oxide ion, O2–.
• Fluorine, with the configuration [He]2s22p5,
gains one electron to become the fluoride
ion, F–.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 1A Elements:
The Alkali Metals
• Because of their chemical reactivity, the alkali
metals don’t exist as free elements in nature.
• Sodium, for example, is
found mostly combined
with chlorine in sodium
chloride.
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Elements: Additional Concepts
Topic
10 Reactivity of the Group 1A Elements:
The Alkali Metals
• Metallic sodium is obtained from NaCl
through a process called electrolysis in which
an electric current is passed through the
molten salt.
Elements: Additional Concepts
Topic
10 Spontaneous Reactivity
• Sodium and the other Group 1
elements are among the most
active of all the metals.
• All Group 1 metals react
vigorously with water.
• When they do, they replace
hydrogen and form a
hydroxide, as shown in the
following equation.
Elements: Additional Concepts
Topic
10 Alkali Metals Form Hydroxides
• So much heat is generated in the rapid reaction
of potassium and water that the hydrogen gas
produced in the reaction bursts into flames.
• Potassium hydroxide
(KOH) formed in the
reaction makes the
solution alkaline.
Hydroxides are
important household and
industrial chemicals.
Elements: Additional Concepts
Topic
10 Household, Industrial, and Biological
Uses
• Sodium hydroxide is used in the digestion
of pulp in the process of making paper.
• It’s also used in making soap, in petroleum
refining, in the
reclaiming of
rubber, and in
the manufacture
of rayon.
Elements: Additional Concepts
Topic
10 Household, Industrial, and Biological
Uses
• It is sodium hydroxide’s ability to convert
fats to soap that makes it effective as a
kitchen drain cleaner.
• Compounds of sodium and potassium are
important to the human body because they
supply the positive ions that play a key role
in transmitting nerve impulses that control
muscle functions.
Elements: Additional Concepts
Topic
10 Household, Industrial, and Biological
Uses
• Potassium is also an essential nutrient for
plants.
• It’s one of the three major components of
fertilizers; the other two are also main
group elements—nitrogen and phosphorus.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 2A Elements,
the Alkaline Earth Metals
• The most reactive element in the alkaline
earth group is the one with the largest
atomic radius and, therefore, the least
attraction for its two valence electrons.
• Knowing this, you can predict that radium,
the largest atom in the group, is the most
reactive.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 2A Elements,
the Alkaline Earth Metals
• The trend to increasing reactivity with
increasing size of atom for the alkaline
earth metals is illustrated by the reaction of
the elements with water.
Elements: Additional Concepts
Topic
10 Reactions of Magnesium and Calcium
• Magnesium oxide is also formed when
magnesium is heated in air.
• It burns vigorously, producing a brilliant
white light and magnesium oxide.
• In the process, magnesium loses two
electrons to form the Mg2+ ion, and oxygen
gains two electrons to form the O2– ion.
Elements: Additional Concepts
Topic
10 Reactions of Magnesium and Calcium
• Together, they form the ionic compound MgO.
• The following equation shows what happens.
Elements: Additional Concepts
Topic
10 Reactions of Strontium
• Strontium makes its
presence known by the
brilliant red color of a
fireworks display.
• The red color also
identifies strontium in
laboratory flame tests.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 13 Elements:
The Importance of Aluminum
• Because aluminum is neither as hard nor as
strong as steel, it is often alloyed with other
metals to make structural materials.
• Aluminum alloys are used in automobile
engines, airplanes, and truck bodies where
high strength and light weight are
important.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 13 Elements:
The Importance of Aluminum
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Elements: Additional Concepts
Topic
10 Aluminum in Your Home
• At home, you may find
bicycles, outdoor
furniture, ladders, and
pots and pans that are
made of aluminum or an
aluminum alloy.
Elements: Additional Concepts
Topic
10 Aluminum as a Conductor
• Even though aluminum doesn’t conduct
electricity as well as copper, it costs less to
use aluminum than copper for transmission
of electricity.
• Aluminum cables are much
lighter than copper cables, so
fewer support towers are
needed to hold the miles and
miles of cable that span the
country.
Elements: Additional Concepts
Topic
10 Gallium’s Low Melting Point
• Gallium, indium, and thallium react much
like aluminum.
• But gallium,
shown here, has
an unusually low
melting point,
29.8°C.
• The heat of a hand is sufficient to liquefy
the metal. For comparison, aluminum melts
at 660ºC.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 14 Elements:
•
•
•
•
Silicon
Silicon, like boron, is a metalloid.
It occurs in sand as silicon dioxide, SiO2—
sometimes called silica.
About 59 percent of Earth’s crust is made
up of silica.
In its elemental form, silicon is a hard, gray
solid with a relatively high melting point,
1410ºC.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 14 Elements:
Silicon
• Silicon is in window glass and in the chips
that run computers.
• Compounds of silicon are found in
lubricants, caulking, and sealants.
Elements: Additional Concepts
Topic
10 Special Glasses from Silicon
• Silicon is important in
semiconductors.
• It’s also important in
making alloys and in
ceramics, glass, and
cement.
• The glass-ceramic shown here doesn’t
expand when heated so it won’t break when
exposed to large temperature changes.
Elements: Additional Concepts
Topic
10 “Tin” Cans and Alloys
• Tin (Sn) is best known for its use as a
protective coating for steel cans used for
food storage.
• The coating
protects the steel
from corrosion.
Elements: Additional Concepts
Topic
10 “Tin” Cans and Alloys
• Tin is also a principal component in the
alloys bronze, solder, and pewter.
• Tin is a soft
metal that can
be rolled into
thin sheets of
foil.
Elements: Additional Concepts
Topic
10 The Lead-Acid Storage Battery
• Lead (Pb) has been known and used since
ancient times.
• It’s obtained from the ore galena (PbS).
• Lead is alloyed with tin in solder and
cheaper grades of pewter.
• The most important
use of lead is in the
lead-acid storage
batteries used in
automobiles.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 15 Elements
• Nitrogen, as the chemically unreactive
molecule N2, makes up 78 percent by
volume of Earth’s atmosphere.
• Plants and animals can’t use nitrogen in this
form.
• Lichens, soil bacteria, and bacteria in the
root nodules of beans, clover and other
similar plants convert nitrogen to ammonia
and nitrate compounds.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 15 Elements
• Lightning also converts atmospheric
nitrogen to nitrogen monoxide (NO).
• Plants use these simple nitrogen
compounds to make proteins and other
complex nitrogen compounds that become
part of the food chain.
Elements: Additional Concepts
Topic
10 Ammonia, the Essential Fertilizer
• Ammonia is used as a liquid fertilizer applied
directly to soil, or it can be converted to solid
fertilizers such as ammonium nitrate,
NH4NO3; ammonium sulfate, (NH4)2SO4; or
ammonium hydrogen phosphate,
(NH4)2HPO4.
Elements: Additional Concepts
Topic
10 Two Allotropes of Phosphorus
• White and red phosphorus are two common
allotropes of phosphorus.
• Notice that the white
phosphorus is photographed
under a liquid because this
form of phosphorus, which
has the formula P4 reacts
spontaneously with oxygen
in the air.
Elements: Additional Concepts
Topic
10 Two Allotropes of Phosphorus
• Red phosphorus is used in making matches.
Elements: Additional Concepts
Topic
10 Gallium Arsenide Semiconductors
• Arsenic is a metalloid found widely
distributed in Earth’s crust.
• An increasingly important use of the element
is in the form of the binary compound gallium
arsenide, GaAs.
• Because of its higher speed and performance,
gallium arsenide is now replacing silicon in
some of its semi-conductor applications in
electronic circuitry.
Elements: Additional Concepts
Topic
10 Antimony
• Antimony (Sb) is used primarily in alloys
with other materials, particularly lead.
• Antimony improves the hardness and
corrosion resistance of the metal.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 16 Elements
• Like oxygen, sulfur gains two electrons and
forms the sulfide ion (S2–) when it reacts
with metals or with hydrogen.
• But in its reactions with nonmetals, sulfur can
have other oxidation numbers.
• Much of the sulfur produced in the United
States is taken from deposits of elemental
sulfur by the Frasch process of mining.
Elements: Additional Concepts
Topic
10 Unstable Hydrogen Peroxide
• In your household
chemical storehouse,
you’ll find oxygen in
solutions of hydrogen
peroxide (H2O2),
shown in a brown
bottle.
Elements: Additional Concepts
Topic
10 An Application of Selenium’s
Photosensitivity
• The chemistry of selenium and tellurium is
similar to that of sulfur.
• Selenium has the property of increased
electrical conductivity when exposed to light.
• This property has applications in security
devices and mechanical opening and closing
devices, where the interruption of a beam of
light triggers an electrical response.
Elements: Additional Concepts
Topic
10 Fluorides Prevent Tooth Decay
• Many towns and cities add fluorides to their
water supply, and sodium fluoride (NaF) or
tin(II) fluoride (SnF2) is often added to
toothpastes to prevent tooth decay.
Elements: Additional Concepts
Topic
10 Silver Bromide Coats Photographic
Film
• The compound of the halogens are more
important than the free elements.
• Compounds of chlorine with carbon, such as
carbon tetrachloride and chloroform, are
important solvents.
• Silver bromide (AgBr) is important in the
light-sensitive coating on film.
Elements: Additional Concepts
Topic
10 Reactivity of Group 18 Elements, Noble
Gases
• The lack of reactivity of noble gases is
understandable; all the noble gases have a full
complement of valence electrons and of noble
gasses, therefore, no tendency to gain or lose
electrons.
Elements: Additional Concepts
Topic
10 Reactivity of the Group 3-12 Elements,
Transition Elements: Iron
• Besides its importance as a structural metal,
iron is an essential element in biological
systems.
• It is the iron
ion at the
center of the
heme
molecule that
binds oxygen.
Elements: Additional Concepts
Topic
10 Chromium
• When chromium is alloyed with iron, tough,
hard steels or steels that are corrosion-resistant
are formed.
• Chromium is also alloyed with other transition
metals to produce structural alloys for use in
jet engines that must withstand high
temperatures.
• A self-protective metal, chromium is often
plated onto other materials to protect them
from corrosion.
Elements: Additional Concepts
Topic
10 Zinc
• Like chromium, zinc is a corrosion-resistant
metal.
• One of its principal uses is as a coating on iron
and steel surfaces to prevent rusting.
• In the process called galvanizing, a surface
coating of zinc is applied to iron by dipping
the iron into molten zinc.
Elements: Additional Concepts
Topic
10 Zinc
• Zinc is also important when alloyed with
other metals.
• The most important of these alloys is the
combination of zinc with copper in brass.
Elements: Additional Concepts
Topic
10 Reactivity of Lanthanides and
Actinides: Cerium
• Cerium is the principal metal in the alloy
called misch metal.
• Misch metal is 50 percent cerium combined
with lanthanum, neodymium, and a small
amount of iron.
Elements: Additional Concepts
Topic
10 Other Lanthanides
• Other lanthanides are used in the glass
industry.
• Neodymium (Nd) is used not only to
decolorize glass but to add color to glass.
• When added to the glass used
for welders’ goggles,
neodymium and
praseodymium (Pr) absorb
the eye-damaging radiation
from welding.
Elements: Additional Concepts
Topic
10 Radioactivity and the Actinides
• Uranium (U) is a naturally occurring,
radioactive element used as a source of
nuclear fuel and other radioactive elements.
• Plutonium (Pu) is one of the elements
obtained from the use of uranium as a
nuclear fuel.
Elements: Additional Concepts
Topic
10 Radioactivity and the Actinides
• Some actinides have medical applications: for
example, radioactive californium-252 (Cf) is
used in cancer therapy.
• Better results in killing cancer cells have
been achieved using this isotope of
californium than by sing the more
traditional X-ray radiation.
Additional Assessment Questions
Topic
10
Question 1
Name the elements in the following pair.
Compare them in terms of group number,
number of valence electrons, and metallic
character.
As and Bi
Additional Assessment Questions
Topic
10
Answers
As: arsenic; 5A; 3; metalloid
Bi: bismuth; 5A; 5; metal
Additional Assessment Questions
Topic
10
Question 2
State a use for each element.
A. Se and Cl
B. I and H
C. S and F
Additional Assessment Questions
Topic
10
Answers
A. Se: used in solar panels and photcopiers
Cl: used as a bleach and disinfectant
and to make certain plastics
B. I: silver compound used to coat
photographic film
He: used in balloons and by divers
C. S: used to make sulfuric acid
F: used in toothpaste to protect tooth enamel
Additional Assessment Questions
Topic
10
Question 3
An element is metallic and radioactive. It has
six valence electrons. Identify the element’s
group number and name the element.
Additional Assessment Questions
Topic
10
Answer
Group 6A, polonium
Additional Assessment Questions
Topic
10
Question 4
Compare the period-2 elements that are in
groups 5A, 6A, 7A, and 8A in terms of number
of valence electrons and reactivity.
Additional Assessment Questions
Topic
10
Answers
Nitrogen (group 5A) has five valence
electrons and is relatively unreactive.
Oxygen (group 6A) has six valence electrons
and is reactive.
Fluorine (group 7A) has seven valence
electrons and is extremely reactive.
Neon (group 8A) has eight valence electrons
and is extremely unreactive.
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