In this topic you will learn about how the world is made up of the same basic building blocks.

Some objects are attracted to magnets. Other objects are not. Magnets attract some items made of metal. A metal is a shiny material found in the ground. Many of the items that magnets attract are made from the metals iron and steel. Magnets attract objects made from some other metals, too. Objects made from iron and steel have the property of magnetism. Magnetism is the property of an object that makes it attract iron and some other metals. Natural magnets come from a rock called magnetite. Magnetite is not a very strong magnet. Permanent magnets, made from iron and steel, are usually stronger than magnetite.

Iron is a very useful metal. It is mixed with other materials to make steel. Steel is a metal used to build buildings, railroads, and bridges. Your body uses iron in foods like meat and spinach to help keep healthy.

The metals iron, gold, silver, aluminum, and copper are elements. An element is a building block of matter. There are over 100 different elements.

Some elements, like the metals iron and copper, are solids. Some elements are liquids. Some elements, like helium, are gases. Each element has its own special properties.

When you combine the elements iron and oxygen you get a compound called rust. A compound may form when two or more elements are put together. The compound salt is made up of the elements sodium and chlorine. Water is a compound, too. It is made of the elements hydrogen and oxygen. Remember that when a mixture is formed, different types of matter are combined together. The properties of the matter in the mixture are not changed. However, the properties of a compound are different from the properties of the elements that make it up.