The periodic table is arranged so that elements with similar chemical properties are placed together. The elements in the periodic table can be classified as metals, metalloids, and nonmetals. Metals have a characteristic sheen, or luster, and conduct electricity. Metals generally have low ionization energy, which is the amount of energy needed to take an electron of an atom. They also tend to form cations, positively charged ions, in a solution. Metals are easily oxidized, meaning they lose electrons to other molecules. Many metals are also ductile, so they can be reshaped and reformed without breaking. On the other hand, many nonmetals do not have a luster and are poor conductors of electricity. Nonmetals vary in their properties. While some nonmetals are not reactive, others are extremely strong oxidizers. Metalloids show properties that are found both in metals and nonmetals. Metalloids are generally shiny, similar to metals, but they are usually brittle, similar to nonmetals. The unique properties of metalloids allow them to be commercially suitable where metals and nonmetals would not be suitable.
At A Glance
- In the periodic table, elements with similar chemical properties are placed together in groups. Elements can be classified as metals, metalloids, and nonmetals.
Metals can be found in groups 1–13 on the periodic table and tend to have high melting and boiling points, conduct electricity, have low ionization energy, and have low electronegativity. Main group metals consist of groups 1 and 2 and parts of groups 13–16. Groups 1 and 2 metals have common characteristics.
- There are seven metalloids: boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), and polonium (Po). Metalloids have electronegativity values between those of metals and nonmetals. Metalloids behave like metals in some conditions and like nonmetals in others. In certain conditions, it is possible to combine advantages of both metals and nonmetals in metalloids.
Nonmetals can be found in groups 14–17 and all of group 18. Nonmetals tend to have properties opposite of metals: they often have low melting and boiling points, conduct electricity poorly, have high ionization energy, and generally have high electronegativity.
Carbon is a group 14 element and can make up to four covalent bonds with four atoms and is a versatile element that can form many shapes. Carbon molecules form the basis of life on Earth—all living matter is based on carbon molecules.
Oxygen is a group 16 element and is very reactive, reacting with metals and nonmetals to form various compounds.
Nitrogen and phosphorus are elements from group 15 of the periodic table. Nitrogen is an essential element for living things on Earth because it is crucial for both plant and animal biological function, and phosphorus is very important in industry.
- The elements found in group 17 are known as the halogens and have 7 electrons in their outer shell. The elements found in group 18 are known as the noble gases and have a complete number of electrons in their outer electron orbital, called a valence shell, making them stable and mostly chemically inert.