What is plasma?
We have seen the three main states of matter but there is actually a fourth one too called plasma. Like gas, plasma particles are not closely bound together and can move around freely. The difference is that plasma contains free ions and electrons which means they can give off light and conduct electricity. This is why plasma is called ionized gas.
Auroras are plasmas that can be seen in some parts of the world, they light up the sky beautifully in a wide array of colours. They occur when atoms from the upper atmosphere are affected by outer space particles.
The Sun, stars, and lightning are all in a plasma state. Some fluorescent lights and neon signs are too.
Elements and compounds
Chemicals that are made up of only one kind of atom are called elements.
Chemicals that are made up of more than one kind of atom are called compounds. Water is a compound of hydrogen and oxygen.
Chemicals and chemical reactions
Water is an example of a chemical. The definition of a chemical is a substance that cannot be separated into components without breaking chemical bonds. Chemicals are known for having a constant chemical composition. They can be pure or mixed. Gold, salt, diamond and water are all pure chemicals. Most chemicals change into other substances by swapping atoms or linking with other chemicals. These exchanges are called chemical reactions.
This might sound a bit complicated but it’s really simple. Let’s take a look at one of the most common chemicals found on Earth: pure water, also known as H20. It is made up of two atoms of hydrogen and one atom of oxygen. It always has this composition whether it’s from a river or a fountain (it has a constant composition). To separate the two hydrogens from the oxygen you would have to break the chemical reaction between them.
All kinds of chemical reactions take place in and around us every day. Simple reactions consist of two elements which join and together form a compound. Water is a simple compound of hydrogen and oxygen. More complex reactions take place during digestion.
A nail turns rusty because of chemical reactions, even making bread requires chemical reactions!
