Nonmetals — Overview & Properties

Nonmetals of the Periodic Table

These elements are found on the right side of the periodic table, except hydrogen. There are eighteen nonmetal elements. They have a variety of chemical and physical properties.

Physical Properties of Nonmetals

• The nonmetals exist in various states of matter: solid, liquid, and gas.

• There are eleven gasses that make up the periodic table. They include the noble gases in group 18 (He, Ne, Ar, Kr, Xe, Rn), hydrogen (H), nitrogen (N), oxygen (O), and two halogens (F, Cl). Most of the nonmetal gases are colorless. The exceptions are the two halogens.

• There is only one liquid nonmetal, bromine (Br).

• The rest of the nonmetals are solids at room temperature (C, P, S, Se, I). Solid nonmetals are brittle. But they often have a silvery appearance and can be confused for metals.

• The nonmetals are generally poor conductors of heat and electricity.

• There are exceptions. For example, some of the carbon allotropes, like graphene, have delocalized pi-electrons. The resonance structures allow it to conduct electrons.

• As a fun fact, Oganesson (OG) is the only synthetically prepared nonmetal element.

Nonmetals

(Video) GCSE Chemistry - Metals and Non-Metals #8

By: Cognito

This video goes into detail about both nonmetals and metals. This video shows where on the periodic table nonmetals are located, properties and reactivity of nonmetals, as well as compares nonmetals and metals to better understand their differences.

Chemical Properties of the Nonmetals

The nonmetals have unique chemical properties. As we move across the periodic table, the atomic number increases. Each nucleus has one more protons. So, the effective nuclear charge on the valence shell also increases. Each element has a smaller atomic radius. What's the result? It holds more tightly to its electrons. The more tightly they retain their electrons, the greater the electronegativity. The nonmetals all have moderate to high electronegativities. So, they participate in a wide range of bonding. For example, the halogens form ionic bonds with metals. They readily take an electron to achieve a full octet. But carbon almost exclusively generates covalent bonds. Carbon is distinctive because of its moderate electronegativity. When it bonds to a very electronegative element, it yields a polar covalent bond. But carbon can also evenly share its electrons. For example, the carbon-hydrogen bond is nonpolar. Carbon's bonding is so diverse that it gets an entire branch of chemistry. That's organic chemistry!

What happens as we move down the periodic table? As we move down, the elements begin to access the d-orbitals. From our electron configurations, we know that the d-orbitals hold ten electrons. So, these elements can break the octet rule! For example, phosphorous and sulfur can bond to five or six halogens. So, we generate compounds like phosphorus pentachloride and sulfur hexafluoride.

We should also discuss hydrogen. It only has one electron. But that gives it incredible diversity. For example, it forms ionic bonds with halogens. What happens if we put a hydrogen-halogen compound in water? It breaks apart! We've created a hydrogen ion. That's the simplest definition of an acid! But what if hydrogen bonds to a slightly less electronegative element? Let's consider hydrogen bonded to oxygen. That creates a special polar covalent bond. What's an example? The best-known example is water! The polar hydrogen-oxygen bond allows water to hydrogen bond, giving it unique properties. For example, its ability as a solvent, its expansion when freezing, its surface tension, and its ability to cohere and adhere are all because of hydrogen bonding.

Overall, we see that the chemistry of the nonmetals is incredibly diverse!