Chapter 3 Section 3

1. Chapter 3 Section 3 Nonmetals and Metalloids

2. What is a Nonmetal? • Nonmetals are the elements that lack most of the properties of metals. • The nonmetals are located to the right of the zigzag line in the periodic table. • Many of the nonmetals are very common elements, as well as extremely important to all living things on Earth.

3. Physical Properties of Nonmetals • Many of the nonmetal elements are gases at room temperature, which means they have low boiling points. • The air you breathe is made mostly of two nonmetals, nitrogen (N) and oxygen (O). • Carbon (C) and Iodine (I) are solids at room temperature • Bromine (Br) is the only nonmetal that is liquid at room temperature. • In general, the physical properties of nonmetals are opposite to those that characterize the metals

4. Solid Nonmetals • Solid nonmetals are dull and brittle, not shiny and malleable or ductile. • If you pound a nonmetal solid with a hammer, it will break easily and crumble into a powder. • Nonmetals usually have lower densities than metals. They also are poor conductors of heat and electricity.

5. Chemical Properties • Most nonmetals easily form compounds. • The exception to this is Group 18 elements. This has to do with valence electrons. • Atoms in Group 18 elements do not gain, lose or share electrons. • The rest of the nonmetals have atoms that can gain or share electrons. • The atoms of these nonmetals can react with other atoms, leading to the formation of compounds.

6. Compounds of Nonmetals and Metals • When nonmetals and metals react, valence electrons move from the metal atoms to the nonmetal atoms. • Group 17 elements react easily this way. • The product of one reaction between a metal and nonmetal from Group 17 is a compound called a salt. An example of a salt is common table salt (NaCl) which is formed from Sodium (Na) and Chlorine (Cl). Other examples include rust.

7. Nonmetals and Nonmetals • Nonmetals can also form compounds with other nonmetals • The atoms share electrons and become bonded together into molecules. • Many nonmetals even form molecules of two identical atoms called diatomic molecules. • Examples of diatomic molecules are oxygen (O2), Nitrogen (N2), and Hydrogen (H2).

8. Families of NonmetalsThe Carbon Family • Group 14 is also known as the carbon family. • Each element in the carbon family has atoms with four valence electrons. • Only one of the elements is a nonmetal and that element is carbon. • The next two elements, silicon and germanium are metalloids. Tin and lead are metals. • Carbon is especially important because of its role in the chemistry of life. • All living things contain compounds that are made of long chains of carbon atoms.

9. The Nitrogen Family • Group 15, the nitrogen family, contains elements that have five valence electrons in their atoms. • The two nonmetals in the family are nitrogen and phosphorus. • The atmosphere is almost 80 percent nitrogen so you breathe it everyday. • Nitrogen does not readily react with other gases so you breathe out as much nitrogen as you breathe in.

10. Who uses Nitrogen? • Living things do use nitrogen, but most living things are unable to use the nitrogen in the air. • Certain kinds of bacteria are able to combine with nitrogen in the air with other elements. • Plants can take up the nitrogen compounds formed in the soil by the bacteria. • Farmers add nitrogen compounds to the soil in the form of fertilizer. • Like all animals, humans get the nitrogen from the food we eat, from plants, or from animals that eat plants.

11. The Oxygen Family • Group 16, the oxygen family, contains elements that have six valence electrons in their atoms. • An atom in Group 16 typically gains or shares two electrons when it reacts. • The three nonmetals in group 16 are oxygen, sulfur, and selenium (rare element).

12. Uses of Oxygen • When you breathe, you use oxygen in the air. • Oxygen travels through your lungs and into your bloodstream, which distributes it to your body. • You could not live long without a steady supply of oxygen. • The oxygen you breathe is a diatomic molecule. (O2) • Oxygen sometimes forms a triatomic (three atom) molecule, called ozone (O3) • Ozone collects in a layer in the upper atmosphere, where it screens out harmful radiation from the sun.

13. Oxygen cont. • Oxygen is very reactive, and can combine with almost every other element. • It also is the most abundant element in Earth’s crust and the second most abundant in Earth’s atmosphere. • Sulfur is the other common nonmetal in the oxygen family. • If you have ever smelled a rotten egg, then you are familiar with the smell of many sulfur compounds. • You can find sulfur in rubber bands, tires, and many medicines.

14. The Halogen Family • Group 17 contains fluorine, chlorine, bromine, iodine, and astatine. • All but one of the halogens are nonmetals, and all share similar properties. • A halogen atom has seven valence electrons and typically gains or shares one electron when it reacts.

15. Uses of Halogens • All of the halogens are very reactive, and most of them are dangerous to humans. • However, many of the compounds that halogens form are also quite useful. • Fluorine, the most reactive of all the nonmetals, is found in nonstick cookware and compounds that help prevent tooth decay. • Chlorine is found in table salt and other salt compounds. • Bromine reacts with silver to form silver bromide which is used photographic film.

16. The Noble Gases • Group 18 is known as the noble gases. • In some cultures, “noble” individuals hold a higher rank than ordinarypeople. • The noble gases do not ordinarily form compounds with other elements. • This is because atoms of noble gases do not gain, lose, or share their valence electrons. • As a result, the noble gases are chemically very stable and unreactive.

17. Where are Noble Gases Found? • All of the noble gases exist in Earth’s atmosphere, but only in small amounts. • Because of the stability and relative scarcity of the noble gases, most were not discovered until the late 1800’s. • Helium was discovered by a scientist who was studying the sun, not the atmosphere.

18. Uses of Noble Gases • We use helium to make balloons float. • Noble gases are also used in glowing electric lights. They are commonly known as neon lights. • Neon lights are often filled with argon, xenon, and other noble gases.

19. Hydrogen • Alone in the upper left hand corner of the periodic table is the simplestelement called hydrogen. • Usually each of its atoms contains only one proton and one electron. • Because the chemical properties of hydrogen differ so much from those of other elements, it cannot be grouped into a family.

20. Uses of Hydrogen • Hydrogen makes up more than 90 percent of the toms in the universe, it makes up only 1 percent of the mass of Earth’s crust, ocean, and atmosphere. • Hydrogen is rarely found on Earth as a pure element. • Most of it is combined with oxygen in water. • If the chemical bonds in water are broken, then diatomic hydrogen gas molecules are formed. (H2)

21. The Metalloids • On the border between the metals and the nonmetals are seven elements called metalloids. • The metalloids have some of the characteristics of metals and some of the characteristics of nonmetals. • The most common metalloid is silicon (Si). • Silicon combines with oxygen to form a number of substances (sand, glass, and cement).

22. Uses of Metalloids • The most useful property of the metalloids is their varying ability to conduct electricity. • Whether or not a metalloid conducts electricity can depend on temperature, exposure to light, or the presence of small amounts of impurities. • For this reason, metalloids such as silicon and germanium (Ge) are used to make semiconductors.

23. Semiconductors • Semiconductors are substances that under some conditions can carry electricity, like a metal, while under other conditions cannotcarry electricity, like a nonmetal. • Semiconductors are used to make computer chips, transistors, and lasers.