Download Group 13: The Boron Group

1 Group 13: The Boron Group
Group 13: The Boron Group
The Boron Family contains the semi-metal Boron (B) and metals Aluminum (Al),
Gallium (Ga), Indium (In), and Thallium (Tl).
Contents
1. Properties & Periodic Trends
2. Individual Properties
2.1. Boron
2.1.1. Fun Facts
2.2. Aluminum
2.2.1. Fun Facts
2.3. Gallium
2.3.1. Fun Facts
2.4. Indium
2.4.1. Fun Facts
2.5. Thallium
2.5.1. Fun Facts
3. Outside links
3.1. Boron
3.2. Aluminum
3.3. Gallium
3.4. Indium
3.5. Thallium
4. References
5. Problems
6. Contributors
Properties & Periodic Trends
These elements are located in Group 13 (XIII) of the p-block in the Periodic Table of
Elements.
Fig 1. Periodic Table with Boron Family in blue.
2 Group 13: The Boron Group
They have three electrons in their outermost shell (a full s-orbital and one electron
in the p-orbital) with a valence electron configuration: ns2np1. The Boron Group has
oxidation states +3 or +1. The +3 oxidation states are favorable except for the
heavier elements such as Tl, which prefers +1 oxidation state due to its
stability. This is known as the inert pair effect.
The elements in the Boron Group follow these periodic trends:



Atomic Radius tends to increase going down the group (Tl has the largest atomic
radius.)
Electrode potential increases going down the group (reactivity decreases as
going down group)
Ionization Energy decreases going down the group (since the electrons are
farther from the core and therefore are easier to remove)1
Fig 2. Properties & Trends
Individual Properties
Boron
Boron is the first element of Group 13 and is the only semi-metal of this group. It
has properties of both a metal and a nonmetal. It has the electron configuration
[He] 2s2 2p1 and its oxidation is usually +3. This element does not exist alone but
instead as compounds which are widely found in the Earth's crust. Also there are a
few locations where boron ores, known as borax, are found in great concentrations.
Boron is an essential nutrient for plants. It forms hydrides and the simplest boron
hydride found is diborane, B2H6. Boron hydrides are used to synthesize organic
1
Tl does not follow normal trends
3 Group 13: The Boron Group
compounds. One main compound used to form other boron compounds is boric acid.
Boric acid is a weak acid and may be formed by the following reaction:
B2O3 (s) + 3 H2O
(l)
 2 B(OH)3 (aq)
B(OH)3 (aq) + 2 H2O(l)  H3O+(aq) + B(OH)4-(aq)
Fun Facts




When burned, Boron produces green flames. [1]
There is a town in California named Boron because it is home to the largest
Borax mine in the world.
Research indicates Boron may be beneficial for the treatment of arthritis.
Boric acid is found in products that we use in our daily lives such as
disinfectants, insecticide, glass, bleaches, and dyes.
Aluminum
Fig 3. Aluminum found in the kitchen
Aluminum is the most important metal in the Boron Group. It has the electron
configuration [Ne] 2s2 2p1 and its oxidation state is usually +3. This element is the
most abundant metal in the Earth's crust (7.5-8.4%). Even though it is very
abundant, before 1886 aluminum was a semiprecious metal. Aluminum was hard to
isolate due to its high melting point. However in 1886, two scientists
simultaneously discovered a method to isolate the element through electolysis.
Aluminum is a soft malleable metal with a silver or gray color. It is a very reactive
element so it is found in nature combined with other elements. One would think
aluminum will react with water but in reality aluminum is protected by a layer of
Al2O3, which is known as anodizing. The thickness of the layer can vary through
galvanic reactions. Aluminum is a good reducing agent. Aluminum extracts oxygen
from any metal oxide. This reaction is known as the thermite reaction:
Fe2O3(s) + 2 Al(s) -> Al2O3(s) +2 Fe(l)
Fun Facts


45% Al produced in the U.S. is from recycling aluminum scraps.
Impure Al2O3 are found as gemstones such as ruby and sapphire.
4 Group 13: The Boron Group
Gallium
Gallium has the electron configuration [Ar] 2s2 2p1 and +3 oxidation state. It has a
relatively low melting point of 29.8º C. Gallium is important because it forms gallium
arsenide (GaAs), which can convert light into electricity.
Fun Facts

Due to its low melting point, gallium can melt in your hands.
[8]
Indium
Indium has the electron configuration [Kr] 2s2 2p1 and may have a +1 or
+3 oxidation state, though the +3 oxidation state is more common. It is a soft
malleable metal similar to gallium. Indium can form InAs which is found in
photoconductors in optical instruments.
Fun Facts

A thin layer of indium can be found on LCD displays.
Fig 4. LCD screen on the keyboard containing a thin layer of indium
Thallium
Thallium has the electron configuration [xe] 2s2 2p1 and has the +3 or +1 oxidation
state. As previously stated, since thallium is heavier, it has a greater stability in
the +1 oxidation state (inert pair effect). Hence, it is found more commonly in its
+1 oxidation state. Thallium is soft and malleable. It is very poisonous and was
widely used in insecticide and rat poison until 1975 when the U.S. prohibited such
usage because of its high toxicity. Currently its usage is limited and must be
handled with care. Nevertheless it is still used for high-temperature
superconductors.
Fun Facts


Thallium changes color when exposed to air (metallic gray color  Bluish-grey
tint)
Thallium has no taste or odor warning its presence.
5 Group 13: The Boron Group
Outside links
Boron
1. illustration of green flame and more fun
facts: http://www.youtube.com/watch?v=JzqdHkpXuy4 [1]
2. Pictures and ways how boron is used in our
lives: http://www.youtube.com/watch?v=vPPX6O9O9YQ&feature=related
[2]
Aluminum
1. Great facts for aluminum: http://www.youtube.com/watch?v=p2cicHXMs1w [3]
2. Aluminum foil in the
microwave: http://www.youtube.com/watch?v=EFLUeH38ITM [4]
3. Aluminum-Chemical of the
Week: http://scifun.chem.wisc.edu/chemweek/Aluminum/ALUMINUM.html [5]
Gallium
1. Great video of gallium: http://www.youtube.com/watch?v=9TsA4qYsy0I [6]
2. Aluminum and gallium combined to reduce water to
hydrogen: http://www.youtube.com/watch?v=4tvR1khXKnI [7]
3. Gallium in liquid form on the hand: http://www.youtube.com/watch?v=wG-oGDHZu8 [8]
Indium
1. Fun facts of indium: http://www.youtube.com/watch?v=4opHafNmgCw
[9]
Thallium
1. Warning about thallium
poisoning: http://www.youtube.com/watch?v=bK6nnyibhdk
2. Fact sheet: http://www.speclab.com/elements/thallium.htm
[10]
[11]
References
1. Petrucci, Ralph H, William Harwood, and F. Herring. General Chemistry:
Principles and Modern Applications. 8th Ed. New Jersey: Pearson Education Inc,
2001.
2. Richard L. Travers, et al. "Boron and Arthritis: The Results of a Double-blind Pilot
Study." Journal of Nutritional & Environmental Medicine. 1.2 (1990): 127-132.
3. Silberberg, Martin. Chemistry: The Molecular Nature of Matter and Change.
4th Ed. New York: McGraw-Hill Science/Engineering/Math, 2004
6 Group 13: The Boron Group
Problems
1. T/F Although aluminium theoretically reacts with water, in reality aluminum
forms a protective layer that blocks such reaction.
2. Which of the following statements about Gallium is false?
a.
b.
c.
d.
Melts in your hands
Can combine with Aluminum to reduce water
Mainly found in the oxidation state +1
Can form a great source of hydrogen
3. T/F Thallium is highly toxic and therefore it is commonly used for rat poisons and
insecticides in the United States.
4. Boron:
a.
b.
c.
d.
e.
has the electron configuration [Ne] 2s2 2p1
is the first metal of Group 13.
has an atomic number 6.
is an important element that we use in our daily lives.
All of the above is correct.
5. Which statement is False?
a.
b.
c.
d.
e.
Thallium is the heaviest element.
Boron has the highest melting point.
Electron potential increases going down the group.
Thallium has the lowest ionization energy.
All of the above is correct.
Answers
1.
2.
3.
4.
5.
True. This is anodizing.
C
False. Since 1975, thallium is prohibited from such usage.
D
D
Contributors

Stephanie Lee (UCD)