What are Nonmetals?
In chemistry, a nonmetal is a chemical element that generally lacks a predominance of metallic properties; they range from colorless gases to shiny and refractory (high melting point) solids. The electrons in nonmetals behave differently from those in metals.
With some exceptions, those in nonmetals are fixed in place, resulting in nonmetals usually being poor conductors of heat and electricity and brittle or crumbly when solid.
The electrons in metals are generally free moving and this is why metals are good conductors and most are easily flattened into sheets and drawn into wires. Nonmetal atoms are moderate to highly electronegative; they tend to attract electrons in chemical reactions and form acidic compounds.
Two nonmetals, hydrogen, and helium make up about 99% of ordinary matter in the observable universe by mass. Five nonmetallic elements, hydrogen, carbon, nitrogen, oxygen, and silicon, largely make up the Earth’s crust, atmosphere, oceans, and biosphere.
Most nonmetals have biological, technological, or domestic roles or use. Living organisms are composed almost entirely of nonmetal hydrogen, oxygen, carbon, and nitrogen. Nearly all nonmetals have individual uses in medicine and pharmaceuticals; lasers and lighting; and household items.
what are the nonmetals in the periodic table?
The metals are to the left of the line (except for hydrogen, which is a nonmetal located on the left top corner), the nonmetals are to the right of the line, and the elements immediately adjacent to the line are the metalloids.
Nonmetals have high ionization energies and high electron affinities, so they gain electrons relatively easily and lose them with difficulty. They also have a larger number of valence electrons and are already close to having a complete octet of eight electrons.
The nonmetals gain electrons until they have the same number of electrons as the nearest noble gas (Group 8A), forming negatively charged anions that have charges that are the group number minus eight.
That is, the Group 7A nonmetals form 1- charges, the Group 6A nonmetals form 2- charges and the Group 5A metals form 3- charges. The Group 8A elements already have eight electrons in their valence shells, have little tendency to either gain or lose electrons, and do not readily form ionic or molecular compounds.
Ionic compounds are held together in a regular array called a crystal lattice by the attractive forces between the oppositely charged cations and anions. These attractive forces are very strong, and most ionic compounds, therefore, have very high melting points. For instance, sodium chloride, NaCl, melts at 801°C, while aluminum oxide, Al2O3, melts at 2054°C.
Ionic compounds are typically hard, rigid, and brittle. Ionic compounds do not conduct electricity, because the ions are not free to move in the solid phase, but ionic compounds can conduct electricity when they are dissolved in water.
When nonmetals combine with other nonmetals, they tend to share electrons in covalent bonds instead of forming ions, resulting in the formation of neutral molecules. Keep in mind that since hydrogen is also a nonmetal, the combination of hydrogen with another nonmetal will also produce a covalent bond.
Molecular compounds can be gases, liquids, or low melting point solids, and comprise a wide variety of substances.
List of nonmetals on the Periodic table
Here is a complete list of all the 18 nonmetals on the Periodic table.
| Atomic number | Symbol | Name of element |
| 1 | H | Hydrogen |
| 2 | He | Helium |
| 6 | C | Carbon |
| 7 | N | Nitrogen |
| 8 | O | Oxygen |
| 9 | F | Fluorine |
| 10 | Ne | Neon |
| 15 | P | Phosphorus |
| 16 | S | Sulfur |
| 17 | Cl | Chlorine |
| 18 | Ar | Argon |
| 34 | Se | Selenium |
| 35 | Br | Bromine |
| 36 | Kr | Krypton |
| 53 | I | Iodine |
| 54 | Xe | Xenon |
| 85 | At | Astatine |
| 86 | Rn | Radon |
Properties of Nonmetals
In general, non-metals are brittle, dull, and have poor conductors of heat and electricity. They tend to have lower melting points than metals. Most of the nonmetals exist in two of the three states of matter at room temperature: gases and solids, except bromine, which exists as a liquid.
Nonmetals have high ionization energies and electronegativities. Most nonmetals have the ability to gain electrons easily. Nonmetals display a wide range of chemical properties and reactivities.
Physical Properties of Nonmetals
The following are the properties of Nonmetals:
- Nonmetals have high ionization energies.
- They have high electronegativities.
- Nonmetals are insulators which means that they’re poor conductors of electricity.
- They are dull, they do not have luster like metals.
- Nonmetals are poor conductors of heat. They’re poor thermal conductors.
- They are very weak and brittle. They tend to easily break or shatter.
- Nonmetals have a low density. They’re light for their size.
- They aren’t good conductors of sound and do not make sounds when they are hit.
- They tend to gain electrons easily.
- Nonmetals may be solids, liquids, or gaseous.
- Nonmetals form acidic oxides.
- They’re good oxidizing agents.
- Generally, Nonmetals have four to eight electrons in the outer shell.
Chemical Properties of Nonmetals
The chemical properties of nonmetals:
- Nonmetals are poor conductors of heat and electricity. Graphite and Gas carbon are exceptions.
- Unlike metals, nonmetals aren’t malleable and ductile.
- Nonmetals react more with metals than with nonmetals.
- Usually, nonmetals react with other nonmetals at high temperatures.
- Most nonmetals do not react with air at room temperature.
- White phosphorus is the only nonmetal that reacts with air to form its oxide by burning.
- Usually, nonmetals do not react with water. Except for Chlorine, chlorine dissolves in water to form an acidic solution.
- Nonmetals have a low density.
- They do not form alloys. However, nonmetals like carbon, silicon, and phosphorous.
- Nonmetals exist in all states of matter at room temperature.
- Different nonmetals have different reactions.
- Chlorine is the most reactive metal in the halogen family i.e., Chlorine (Cl), Bromine (Br), Iodine (I), and Fluorine (F). The reactivity order of the halogen family is Cl > Br > I.
- Therefore, Chlorine (Cl) can displace Bromine (Br) and Iodine (I) from solutions of bromides (NaBr) and Iodides (NaI).
- Ionic solids are formed when nonmetals with high electronegativity react with alkali and alkaline earth metals.
Examples of Nonmetals
Examples of nonmetals include hydrogen, carbon, chlorine, helium, fluorine, nitrogen, phosphorus, and selenium.
Nonmetal Gas Elements
Most of the nonmetals are clear, odorless gases at room temperature. Hydrogen, helium, nitrogen, oxygen, neon, argon, krypton, xenon, and radon all fit into this category. 78% of our atmosphere is made up of nitrogen atoms, while 20% is made up of oxygen.
Chlorine is a yellow-green-colored gas with a distinct odor that burns the nostrils in high doses. You may have smelled it when visiting a chlorinated pool. Fluorine is a yellow gas that is equally unpleasant to smell and definitely more toxic. Radon is unstable and often radioactive. It seeps into underground basements and must be pumped out through ventilation systems.
Bromine is a brown liquid at room temperature that readily evaporates into a deep orange gas. It’s the only nonmetal element that exists in liquid form. Like chlorine and fluorine, bromine has a distinct odor and can be quite toxic.
Solid Nonmetal Elements
The remaining elements, carbon, phosphorus, sulfur, selenium, and iodine, exist in solid forms at room temperature. Each of these nonmetal elements has several different solid forms it can exist in, though some forms are more common than others.
For example, carbon is most commonly found as graphite, but it also forms diamonds. The most common form of sulfur is yellow and brittle solid and slightly stinky, like rotten eggs. Phosphorus has many forms, one of which is a gas, white phosphorus, that can ignite if exposed to oxygen. Iodine is often a brown solid that easily sublimes into purple vapors.
Noble Gases
Six nonmetals are classified as noble gases: helium, neon, argon, krypton, xenon, and radioactive radon. In conventional periodic tables, they occupy the rightmost column. They are called noble gases in light of their characteristically very low chemical reactivity.
They have very similar properties, all being colorless, odorless, and non-flammable. With their closed outer electron shells, the noble gases have feeble interatomic forces of attraction resulting in very low melting and boiling points. That is why they are all gases under standard conditions, even those with atomic masses larger than many normally solid elements.
Chemically, noble gases have relatively high ionization energies, nil or negative electron affinities, and relatively high electronegativities. Compounds of the noble gases number in the hundreds although the list continues to grow, with most of these occurring via oxygen or fluorine combining with either krypton, xenon, or radon.
