Farmers Each year farmers test their soil to determine the level of nutrients, the matter needed for plants to grow. The results of the test help the farmer decide how much nitrogen, phos- phorus, and potassium to add to the fields. The addi- tional nutrients increase the chance of having a suc- cessful crop.
Group 15—The Nitrogen Group At the top of Group 15 are the two nonmetals—nitrogen and phosphorus. Nitrogen and phosphorus are required by living things and are used to manufacture various items. These elements also are parts of the biological materials that store genetic information and energy in living organisms. Although almost 80 percent of the air you breathe is nitrogen, you can’t get the nitrogen your body needs by breathing nitrogen gas. Bacteria in the soil must first change nitrogen gas into substances that can be absorbed through the roots of plants. Then, by eating the plants, nitrogen becomes available to your body.
Can your body obtain nitrogen by breathing air? Explain.
Figure 9 Nitrogen and phospho- rus are required for healthy green plants. This synthetic fertilizer label shows the nitrogen and phosphorous compounds that provide these.
Ammonia is a gas that contains nitrogen and hydrogen. When ammonia is dissolved in water, it can be used as a cleaner and dis- infectant. Liquid ammonia is sometimes applied directly to soil as a fertilizer. Ammonia also can be converted into solid fertilizers. It also is used to freeze-dry food and as a refrigerant. Ammonia also is used to make nylon for parachutes, as shown in Figure 8. The element phosphorus comes in two forms—white and red. White phosphorus is so active it can’t be exposed to oxygen in the air or it will burst into flames. The heads of matches con- tain the less active red phosphorus, which ignites from the heat produced by friction when the match is struck. Phosphorous compounds are essential ingredients for healthy teeth and bones. Plants also need phosphorus, so it is one of the nutrients in most fertilizers. The fertilizer label in Figure 9 shows the compounds of nitrogen and phosphorus that are used to give plants a synthetic supply of these elements.
Figure 8 Ammonia is used to make nylon, a tough, light fiber capable of replacing silk in many applications, including parachutes.
K CHAPTER 4 Periodic Table
(t)George Hall/CORBIS, (b)Aaron Haupt
Bismuth 83 Bi
Antimony 51 Sb
Nitrogen 7 N
Group 15 The Nitrogen Group
Phosphorus 15 P
Arsenic 33 As