Ch.10 Lesson 3 Nonmetals and Metalloids

Semiconductors

A property of metalloids is the ability to act as a semiconductor. A semiconductor conducts electricity at high temperatures, but not at low temperatures. At high temperatures, metalloids act like metals and conduct electricity. But at lower temperatures, metalloids act like nonmetals and stop electricity from flowing. This property is useful in electronic devices such as computers, televisions, and solar cells.

Group 17: The Halogens

An element in group 17 of the periodic table is called a HALOGEN. Halogen refers to an element that can react with a metal and form a salt. Very REACTIVE. For example, chlorine gas reacts with solid sodium and forms sodium chloride or table salt. Calcium chloride is another salt often used on icy roads. Halogens react readily with other elements and form compounds. They react so readily that halogens only can occur naturally in compounds. They do not exist as free elements and not exist as a single molecule. They even form compounds with other nonmetals, such as carbon. In general, the halogens are less reactive as you move down the group.

Nonmetals in Groups 14-16

CARBON is the only nonmetal in group 14. It is a solid with different forms. Carbon is in most of the compounds that make up living things. Nitrogen, a gas, and phosphorous, a solid, are the only nonmetals in group 15. These two elements form many different compounds with other elements such as oxygen. Group 16 contains three nonmetals. Oxygen is a gas that is essential for many organisms. Sulfur and selenium are solids that have the physical properties of other solid nonmetals. Form many compounds. Essential for life.

Metals, Nonmetals, and Metalloids

Each metal has unique properties that make it different from other metals. The same is true for nonmetals and metalloids. Nonmetals break easily and do not conduct electricity; conclude that you would not make a wire out of a nonmetal(sulfur in this case). Transition elements are strong, malleable, and do not react easily with oxygen or water.

Metals

Have luster. They are ductile, malleable, and good conductors of electricity and thermal energy. All metals except mercury are solids at room temperature.

Hydrogen

Hydrogen has the smallest atomic mass. It is the most common element in the universe. Hydrogen is most often classified as a nonmetal because it has many properties like those of nonmetals. For example, like some nonmetals, hydrogen is a gas at room temperature. However, hydrogen also has some properties similar to those of the group 1 alkali metals. In its liquid form, hydrogen conducts electricity just like a metal does. In some chemical reactions, hydrogen reacts as if it were an alkali metal. However, under conditions on Earth, Hydrogen usually behaves like a nonmetal.

Metalloids

Located in between the metals and the nonmetals on the periodic table. A metalloid is an element that has physical and chemical properties of both metals and nonmetals. The elements boron, silicon, germanium, arsenic, antimony, tellurium, polonium, and astatine are metalloids. Silicon is the most abundant metalloid in the universe. Most sand is made of a compound containing silicon. Silicon is also used in many different products like electronic devices, glass, medical tubing, and sand. Metalloids are brittle.

Nonmetals

Properties of nonmetals are different from those of metals. Many nonmetals are gases at room temperature. Those that are solid at room temperature have a dull surface, which means they have no luster. Because nonmetals are poor conductors of electricity and thermal energy, they are good insulators.

Properties and Uses of Metalloids

Pure silicon is used in making semiconductor devices for computers and other electronic products. Pure silicon and Germanium are used in semiconductors. Boron is used in water softeners and laundry products. Boron also glows bright green in fireworks. Silicon is one of the most abundant elements on Earth. Sand, clay, and many rocks and minerals are made of silicon compounds.

Group 18: The Noble Gases

The elements in group 18 are known as the noble gases. The elements helium, neon, argon, krypton, xenon, and radon are the noble gases. Unlike the halogens, the only way elements in this group react with other elements is under special conditions in a laboratory. These elements were not yet discovered when Mendeleev constructed his periodic table because they do not form compounds naturally. Once they were discovered, they fit into a group at the far right side of the table. Does not react naturally with other compounds. (Lighting)

Oxygen, carbon, hydrogen, nitrogen, phosphorus, and sulfur

The six elements form the compounds in proteins, fats, nucleic acid, and other large molecules in your body and in all other living things.

nonmetal

are elements that have no metallic properties. Ex: oxygen, carbon, hydrogen, and nitrogen.