Group 3A Elements:

"Boron Group"

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Contains Elements with Atomic Number:

-Boron- 5
-Aluminum- 13
-Gallium- 31
-Indium- 49
-Thallium- 81
-Ununtrium (Unstable, created synthetically)- 113

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Common Properties

Common physical properties of group A3 elements include softness and silvery-grey color, although Boron is non metallic. This is because all of the elements in this group except for Boron are poor metals. The atomic radii of this group increase going from Boron down to Thallium. The same applies to the ionic radii, but the ionic radius of each individual element is less than that of its atomic radius (this involves the outer shell valence electrons being absent in ionized form, thus creating a smaller radius).
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Common chemical properties include a common oxidation state of +3, due to the common property of three valence electrons in the outermost shell. All of the elements in this group form ionic bonds (save for Boron, which forms covalent bonds). Reactivity increases moving down the group. The valence shell of the group 3A elements has a filled s- sub level and one electron in a p- orbital.

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Electron Configurations

Electron Configuration

Meet the Elements:

  • Atomic Number: 5
  • Symbol: B
  • Atomic Mass: 10.811
  • Semi-metallic
  • Color: Usually black
  • First isolated in 1808
  • Solid at room temperature
  • Uses: Metal refining, glass manufacturing, fertilizers, detergents (as borate salts), an insecticide (as boric acid)
  • Atomic Number: 5
  • Symbol: Al
  • Atomic Mass: 26.98
  • Metallic
  • Color: Silvery
  • First isolated in 1825
  • Solid at room temperature
  • Uses: Practically everything. Often in an alloy with other metals, used for electrical wire, cans, foil, airplanes, siding.
  • Third most abundant element in Earth's crust by mass (First and second are Oxygen and Silicon, respectively) and the most abundant metal
  • Aluminum is actually highly reactive- Although it can not be seen, aluminum foil is covered in a small layer of Aluminum oxide

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^ Hans Christian Ørsted, discoverer of Aluminum

  • Atomic Number: 31
  • Symbol: Ga
  • Atomic Mass: 69.72
  • Metallic
  • Color: Silvery-white
  • Discovered in 1875, but predicted by Mendeleev in 1871
  • Solid at room temperature, but melts at slightly above
  • Uses: Computer circuits, LEDs
  • Gallium is one of the few metals that can be a liquid near room temperature, and is used in some high temperature thermometers
  • Atomic Number: 49
  • Symbol: In
  • Atomic Mass: 114.82
  • Metallic
  • Color: Silvery grey
  • Discovered in 1863
  • Solid at room temperature
  • Uses: As an alloy to lower the melting point of other metals
  • Canada produces the world's main supply of Indium
  • Atomic Number: 81
  • Symbol: Tl
  • Atomic Mass: 204.38
  • Metallic
  • Color: Silvery white
  • Discovered in 1861, isolated in 1852
  • Solid at room temperature
  • Highly toxic, a known carcinogen
  • Thallium oxidizes in air, resulting in a bluish tinge
  • Atomic Number: 113
  • Symbol: Uut
  • Atomic Mass: 284
  • Metallic
  • Color: unknown
  • Discovered in 2004
  • Most likely solid at room temperature
  • No uses known, but highly unstable
  • Synthesized in labs, not found in nature
  • Ununtrium emits alpha radiation

Other Elemental Information
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Multiple Choice Questions:

1.) Which group 3A element is the most abundant element in Earth’s crust?
a. Indium
b. Gallium
c. Aluminum
d. Boron
2.) Which group 3A element is a known carcinogen?
a. Thallium
b. Gallium
c. Ununtrium
d. Chromium
3.) Which is the common oxidation state for the group 3A elements?
a. +4
b. -3
c. +2
d. +3
4.) Which element of the 3A group is the only non-metal?
a. Aluminum
b. Gallium
c. Carbon
d. Boron
5.) The radius of an Aluminum atom is __ the radius of an Aluminum ion.
a. …less than…
b. …greater than…
c. …the same size as…
d. Aluminum bonds covalently

Works Cited

Boudreux, Kevin. "Group 3A." Mr. Kevin A. Boudreux: Instructor, Department of Chemistry, Angelo State University, San Angelo, Texas. Angelo State University. Web. 21 Nov 2012.

"Home of the Periodic Table." Periodic Table of the Elements by WebElements. N.p., n.d. Web. 27 Nov. 2012.

"Visual Elements: Group 13." chemsoc: the RSC's chemical science network. Royal Society of Chemistry. Web. 21 Nov 2012. <>.