ElementsWhat are the nonmetals?
The nonmetals shown in this family are hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur and selenium. They are poor carriers of heat and electricity, and as solids they are brittle, not bendable. They are few in number but make up most of the air, the oceans and every living thing. The halogens and the noble gases are also nonmetals, but they are listed as their own families.
The family in numbers
Melting points in this family run from -259.3 °C (hydrogen) to 3,550 °C (carbon). Among its solid members, the least dense is phosphorus (1.82 g/cm³) and the densest is selenium (4.81 g/cm³). Known since ancient times: carbon, sulfur. The most recently discovered member is selenium (1817).
How they behave
A metal atom tends to give electrons away. A nonmetal atom tends to take them, or to share them. When a nonmetal meets a metal it takes electrons and forms a salt-like compound, as oxygen does with iron to make rust. When nonmetals meet each other they share electrons and form molecules: water, carbon dioxide, ammonia, methane and sugar are all made only of nonmetals.
The elements of life
Four of these seven elements, carbon, hydrogen, oxygen and nitrogen, make up almost all of the mass of every living thing. Carbon atoms can link into long chains and rings, and the study of those compounds is a whole branch of chemistry, organic chemistry. Phosphorus is in bones and in DNA, and sulfur is in proteins. Hydrogen is the most abundant element in the universe. Nitrogen makes up about 78 percent of the air and oxygen about 21 percent.
One element, several forms
Several nonmetals exist in more than one solid form. Carbon is both diamond, the hardest natural substance, and graphite, the soft grey material of pencil leads. Phosphorus has a white form that catches fire in air and a red form that is safe enough for the striking surface of a matchbox. Oxygen is normally a gas of two-atom molecules, and in its three-atom form it is ozone.
All nonmetals compared
| No. | Symbol | Name | Atomic mass | State | Melts at | Boils at | Density g/cm³ | Discovered |
|---|---|---|---|---|---|---|---|---|
| 1 | H | Hydrogen | 1.0080 | Gas | -259.3 °C | -252.9 °C | 0.00008988 | 1766 |
| 6 | C | Carbon | 12.011 | Solid | 3,550 °C | 3,825 °C | 2.27 | Ancient |
| 7 | N | Nitrogen | 14.007 | Gas | -210 °C | -195.8 °C | 0.0012506 | 1772 |
| 8 | O | Oxygen | 15.999 | Gas | -218.8 °C | -182.9 °C | 0.001429 | 1774 |
| 15 | P | Phosphorus | 30.97376200 | Solid | 44.2 °C | 280.5 °C | 1.82 | 1669 |
| 16 | S | Sulfur | 32.07 | Solid | 115.2 °C | 444.6 °C | 2.07 | Ancient |
| 34 | Se | Selenium | 78.97 | Solid | 220.5 °C | 684.9 °C | 4.81 | 1817 |
Other families: alkali metals, alkaline earth metals, transition metals, post-transition metals, metalloids, halogens, noble gases, lanthanides, actinides.