Document 6509082

Appendix_A.fm Page 3 Monday, June 21, 2004 6:59 AM
How to Use the Elements Handbook
1 Look for data that
First Ionization Energy
Group 1A: Alkali Metals
Atomic Properties
• Alkali metals have an
electron configuration
that ends in ns1.
Physical Properties
Li
Lithium
6.941
11
Na
Lithium | discovered in
1817 by Johan August
Arfvedson
2
8
1
Sodium | discovered in
1807 by Sir Humphry Davy
2
8
8
1
Potassium | discovered in
1807 by Sir Humphry Davy
1
• The presence of a single
valence electron also
explains the low melting
points and boiling points
of alkali metals.
Sodium
22.990
19
K
Rb
2
8
18
8
1
Rubidium
85.468
55
Cs
2
8
18
18
8
Cesium 1
132.91
87
Fr
2
8
18
32
18
Pure alkali metals are stored under
oil because they will tarnish on
exposure to oxygen or moisture in air.
Melting and Boiling Points
Rubidium | discovered in
1861 by Robert Bunsen &
Gustav Kirchhoff
Cesium | discovered in
1860 by Robert Bunsen &
Gustav Kirchhoff
Temperature (C)
37
• The atoms of alkali
metals are the largest
in their periods.
1500
1336
Francium | discovered in
1939 by Marguerite Perey
2
883
900
758
700
670
600
300
0
179
Li
98
64
39
28
Na
K
Rb
Cs
Na
Ionic
radius (pm)
0.97
• The alkali metals are the most reactive metals.
Li
Na
K
Rb
• All alkali metals react with water to form an
alkaline solution. Example:
Cs
2K(s) 2H2O(l)
• Sodium is the only alkali metal
manufactured on a large scale. It is
generally produced by the electrolysis
of molten sodium chloride.
Rb Cs
Fr
0.25
0
Cs
Li
Na
Li
156
Na
191
K
238
Rb
255
Cs
273
60
+
Li
95
Na+
133
K+
148
Rb+
169
Cs+
Sodium
K
Potassium
Rubidium
Molten Na
2Na(l) Cl2(g)
to reveal trends
in properties within
a group.
Calcium
3 Learn where
Graphite anode ()
5
4 Find examples of
typical chemical
reactions.
Uses of NaOH
Pulp and Paper
5%
14%
LiOH(aq) H2(g)
13%
4%
Soaps and
Detergents
Petroleum
• Potassium superoxide, KO2, is a source of
oxygen in submarines. It removes CO2
from the atmosphere as it produces oxygen.
4KO2(s) 2CO2(g)
elements exist in
nature and how
they are processed.
• Sodium hydroxide, NaOH, is used as a drain
cleaner. It is also used to produce other
chemicals and in many industrial processes.
Na2CO3(s) CO2(g) H2O(g)
H 129 kJ/mol
LiH(s) H2O(l)
Steel cathode ()
Lithium and potassium are produced
by a similar process.
describes what the
elements in a group
have in common.
2 Interpret graphs
• Lithium carbonate, Li2CO3, is a prescription
medicine for chronic depression.
• Lithium hydride is a convenient source
for hydrogen.
Molten NaCl
Na(l )
Iron screen
0.7
• Sodium hydrogen carbonate, NaHCO3, is
used in fire extinguishers.
produces CO2(g) and steam, which causes
baked goods to rise.
Cl2(g )
2NaHCO3(s)
• The mineral sylvite, KCl, is a source
of potassium.
0.7
• Potassium nitrate, KNO3, is used in matches
and chemical fertilizers.
2CsCl(s)
H 442.8 kJ/mol
4 • Sodium hydrogen carbonate (baking soda)
Manufacture of Sodium
NaCl
0.8
0.5
• Sodium hypochlorite, NaOCl, is used as a
bleach and to disinfect swimming pools.
2KOH(aq) H2(g)
2Cs(s) Cl2(g)
• Alkali metals do not occur uncombined in
nature because they are highly reactive.
Rb
0.8
0.75
0.86
0.53
• All alkali metals react with halogens to form
an ionic halide. Example:
• Sodium occurs widely as sodium chloride
in underground salt and brine deposits.
It is a major component of seawater.
K
Lithium
3
2NaCl(l)
Li
0.9
Important Compounds and Reactions
Francium 8
1
(223)
Sources
376
150
1.88
1
0
403
300
1.0
1.53
1.5
0.5
419
1.0
Alkali metals can be identified by
the colors produced when their
compounds are heated in a flame.
Density
bp
mp
1200
Electronegativity
496
450
Atomic
radius (pm)
• Cesium metal is used in
photocells because its
first ionization energy is
very low.
2
Potassium
39.098
520
0
• Alkali metals form
ions with a 1 charge.
• Alkali metals are silver-gray
solids that are soft enough
to cut with a knife. They
are soft because they have
only one valence electron.
Density (g/cm3)
2
1
3
Energy (kJ/mol)
600
Electronegativity
Handbook
Elements
Other Industries
35%
32%
Organic Chemicals
Inorganic Chemicals
2K2CO3(s) 3O2(g)
R6 Elements Handbook
R7
Group 1A: Alkali Metals
5 Find out which
compounds have
important industrial
uses.
6 Make connections
Group 2A: Alkaline Earth Metals
Mg Chlorophyll
Sr
A plant that is deprived of
magnesium will turn yellow
and eventually die. The
yellow color is a sign that
the plant is not producing
enough of the green pigment
chlorophyll, which is found in
structures called chloroplasts.
There are about half a million
chloroplasts in one square
millimeter of leaf surface. In
chloroplasts, light energy is
changed to chemical energy.
Producing an aerial
fireworks display requires
skill and knowledge of
chemistry. Shells are stored
in steel pipes anchored in sand.
A typical shell contains two
The name of this effect
is chrysanthemum.
charges, one to launch the shell and
one to cause the shell to burst. When
the lifting charge explodes, the shell is blown out of the pipe
and the fuse attached to the bursting charge ignites. The
shell travels for a few seconds before it bursts.
Chlorophyll molecules
absorb wavelengths of blue
light and red light, and
reflect green light. There is a
magnesium ion at the center
of each chlorophyll molecule.
It is embedded like a jewel
in a crown-like ring. The
magnesium ion forms a bond
with each nitrogen atom.
CH2
CH
H
C
The chemical reactions that form a limestone cave are simple.
Carbon dioxide in the air dissolves in rain to form weak carbonic acid, H2CO3. As rain passes through soil, it dissolves
carbon dioxide produced by decaying plants and becomes
even more acidic. The rainwater seeps into limestone, CaCO3,
beneath the soil. The CaCO3 dissolves in the carbonic acid,
forming a solution of calcium hydrogen carbonate, Ca(HCO 3)2.
Ba Fireworks
The explosions that launch the shells and cause them to
burst are exothermic redox reactions. The reducing agent, or
fuel, may be aluminum, magnesium, or sulfur. The oxidizing
agent may be a nitrate, a chlorate, or a perchlorate, such as
potassium perchlorate (KClO4).
When a shell bursts, it releases tiny pellets called “stars,”
which produce the colors. Only a few elements are needed to
produce these colors. Two are alkaline earth metals, strontium
for bright red and barium for light green. These same colors
are produced when strontium and barium compounds are
heated in a flame. Flame tests can identify elements because
an element emits characteristic wavelengths of light when its
atoms absorb heat and then return to the ground state. ■
7
Ca Limestone Caves
CaCO3(s) H2CO3(aq)
6
N
CH
Mg
N
H
H3C
H
N
C
CH3
CH2 HC C O
CH2
chemical reactions on
the environment.
Ca (aq) 2HCO (aq)
Over millions of years, as more and more limestone dissolves, a
cave forms and slowly grows in size. Once the cave stops growing,
another process may occur. Calcium hydrogen carbonate solution
drips through the cave’s roof. Carbon dioxide is released from
solution, leaving behind a tiny deposit of solid calcium carbonate.
Ca2(aq) 2HCO3(aq)
8 Find out the effects
CaCO 3(s) CO 2(g) H 2O(l)
The deposit slowly grows into a stalactite, which hangs from the
ceiling like an icicle. Drops of solution that fall from the ceiling
form stalagmites on the cave floor. Calcium carbonate is white.
So any color in the deposits is due to traces of metal ions, such
as copper (blue-green) and iron (red-brown). The growth rate
of the formations depends mainly on the volume of water
that drips through the roof and the concentration of calcium
bicarbonate in the water. In many caves, the rate of growth is
measured in centimeters per hundreds or thousands of years. ■
of certain chemicals
on your health.
9 Discover some fun
Stalactites and stalagmites
may join together to
form columns.
CH2CH3
N
7 Explore the impact of
3
2
facts about elements.
CH3
H3C
HC
between chemistry
and technology.
Handbook
Elements
COOCH3
COOC20H39
Chlorophyll a
Chlorophyll is typical of a
family of compounds called
porphyrins, which contain a
central metal ion. In heme,
the ion is Fe2. There are
four heme molecules in
hemoglobin, which transports
oxygen in the blood. ■
R12 Elements Handbook
Labels for shells used in a fireworks display describe
the color and the effect produced by the shell.
Ca Building Strong Bones
As a young adult, you can
have a major effect on the
health of your bones later in
life. You acquire 90% of the
bone tissue in your skeleton
before age 18 as females and
age 20 as males. Physical
activity and the amount of
calcium in your diet affect
the buildup of bone mass.
To maintain a constant level
of calcium in your blood,
your body may release
calcium from bone tissue.
8
If enough calcium is lost
from bones, they become
brittle and tend to break
easily. This condition,
known as osteoporosis, is
most common in older
people. However, it can
occur in young and
middle-aged adults.
The recommended daily
intake of calcium from age
9 to age 18 is 1.3 g per
day. This is the amount
in a liter of milk.
Calcium-fortified foods, such
as orange juice, are a good
choice for those who cannot
tolerate the lactose in milk.
Vitamin D in orange juice
helps you absorb calcium. ■
?
9
Did You Know...
Calcium oxide (lime) emits a bright
white light when it is heated. Before
electric lights, theaters used lime to
focus light on a single actor. So the
expression in the limelight describes
a person in a prominent position.
Group 2A: Alkaline Earth Metals
R13
R3