Gallium is a Block P, Group 13, Period 4 element. The electronic configuration is [Ar] 3d¹⁰ 4s² 4p¹. In its elemental form gallium's CAS number is 7440-55-3. The gallium atom has a radius of 122.1.pm and it's Van der Waals radius is 187.pm. Gallium is one of three elements that naturally occur as a liquid at room temperature. The other two are mercury and cesium. The application of gallium that has received the most attention is the production of semiconducting compounds. Of these, the most important are the compounds of gallium with antimony, arsenic or phosphor.

Indium is a Block P, Group 13, Period 5 element. The electronic configuration is [Kr] 4d¹⁰ 5s² 5p¹. In its elemental form indium's CAS number is 7440-74-6. The indium atom has a radius of 162.6.pm and it's Van der Waals radius is 193.pm. Indium has found application in semi-conductor materials and other electronic applications. It is used to make low-melting alloys, such as an alloy of 24% indium - 76% Indium is liquid at room temperature. It is used in making bearing alloys, germanium transistors, rectifiers, and photoconductors. It can be plated onto metal and evaporated onto glass, forming a mirror as good as that made with silver but with more resistance to atmospheric corrosion.

Arsenic is a Block P, Group 15, Period 4 element. The electronic configuration is [Ar] 3d¹⁰ 4s² 4p³. In its elemental form arsenic's CAS number is 1327-53-3. The arsenic atom has a radius of 124.5.pm and it's Van der Waals radius is 185.pm. Arsenic has numerous applications as a semiconductor and other electronic applications as Indium arsenide, silicon arsenide and tin arsenidea. Arsenic is finding increasing uses as a doping agent in solid-state devices such as transistors.