A chemical that is made up of atoms of just one type is known as an element. Although all atoms are made of the same basic parts-protons, neutrons, and electrons-not all atoms are the same. It is the number of these parts that gives the atom-and the element-its properties.
The number of protons in an atom of an element gives it its atomic number. Scientists arrange elements according to their atomic numbers in a chart known as the periodic table. Although each element is unique, many have similar properties. Those that share certain properties are grouped together.
The first group of similar elements in the periodic table is known as the alkali metals. These elements, which include sodium and lithium, are soft and react with water, forming alkaline solutions.
Most of the metals we use in everyday life, such as gold, iron, and copper, are grouped together as transition metals. This group contains metals that can create magnetic fields and are good conductors of heat and electricity.
Alkaline earth metals
Metals in this group, which includes barium, calcium, magnesium, and radium, are highly reactive, although not quite as reactive as alkali metals. Alkaline earth metals are found in numerous compounds in the Earth’s crust, as well as in our bodies.
The six noble gases – Helium, Neon, Argon, Krypton, Xenon, and Radon-are colorless, odorless, and usually do not react with other elements to form compounds. They are, however, used in a variety of applications, including electric lights. Most noble gases glow brightly when electricity is passed through them. Lighter-than-air helium is also used in balloons and to lift airships.