The periodic table is divided into metals on the left and non-metals on the far right. Separating them are metalloids or semimetals. Metalloids are on either side of a stair-like line and have properties of both metals and non-metals. There are seven metalloids: boron, silicon, germanium, arsenic, selenium, antimony, and tellurium. They conduct electricity, but not as well as metals and are called semiconductors. Their ability to conduct electricity increases with temperature. Semiconductors are used in electronic and for making transistors. A computer chip can hold more than a million transistors. Other devices made from semiconductors include hand-held calculators, digital watches, and desktop computers.

Germanium is a relatively rare element found in transistors. Selenium, although rarer than germanium, has several allotropic forms. Electric conductivity of selenium is increased when light shines on it. In addition to being used as a semiconductor in photoelectric cells and copy machines, selenium is also used in ceramics, glass, and medicine. Like selenium, tellurium is used in electronic devices. The most common form is as a silver, brittle metal-like substance. It is the only element that is found in combination with gold.

Silicon reacts chemically like carbon although it does not form multiple bonds. It is used in making alloys with iron, copper, and bronze. Silicones are chains of silicon and oxygen and have organic groups attached. These polymers, depending on the length of the chain and the pattern of the chain are used for water repellents, oils, lubricants, polishes, antacids, and in paints that resist heat. Pure silicon can be mixed with antimony, arsenic or boron and used to make integrated circuits. Arsenic has two allotropes, yellow arsenic and metallic arsenic, which is brittle. Its major use is as a poison in weed killers and insecticides.

Antimony is used in the manufacture of vases, cosmetics, and ornaments. It also has two allotropes, a metallic, brittle silver white form, and a soft, yellow unstable form. Antimony is used as an alloy with lead in batteries, making it more resistant to acid.