| A | B |
|---|
| Boron | Exists in the earth's crust to the extent of only about 10 ppm (about the same abundance as lead). |
| Aluminum | This element ranks third on the list of the ten most abundant elements in the earth's crust. |
| Thallium | Discovered in 1861, this element was positively identified it by a bright green line in its spectrum (hence the name, which is from the Greek, thallos, for "green twig"). |
| Indium | This element is a rare metal, with an abundance similar to that of silver. |
| Gallium | At room temperature this element is as soft as lead and can be cut with a knife. |
| Aluminum alloys | Has low density and is inexpensive to use to consruct air craft, boats, sports equiptment, etc. |
| B | This pure element is shiny and black. It is very hard and in extremely pure form is nearly as hard as diamond, but much too brittle for practical use. |
| Al | Soft, lightweight and silvery, It is the most abundant metal on the planet. Its name is taken from the Latin alumen for alum. |
| Tl | Although in appearance this element resembles lead, it does not have the corrosion resistance of lead and so has few commercial applications. |
| Ga | This elements melting point is abnormally low and it will begin to melt in the palm of a warm hand. It is also one of a small number of metals that expands when freezing. |
| In | Like pure tin, this element emits a squealing sound when bent. |
