Tuesday, Feb. 24 - Matter - Introduction to Matter, Elements and Atoms

Objective: Understand that all matter is made of atoms. Atoms of different elements have unique properties that determine the properties of the substance they make up.

Anything that has mass and takes up space is matter – the ocean, the earth, you, even air, even though you can’t see it. That’s an important concept. If it has mass and takes up space, it’s matter – whether you can see it or not.

All matter is made up of one or more elements and each element is made up of atoms. An element is a substance in which all the atoms are the same. Essentially, you can’t break an element down any more than it already is. Hydrogen or Oxygen, for example – if you break down Hydrogen or break down Oxygen, you still have Hydrogen or Oxygen because either one of these elements are only made up of Hydrogen atoms or Oxygen atoms.

There are more than 100 elements that occur in nature. They are usually represented by a chemical symbol of one or two letters – O (oxygen) or He (Helium).

So if an element is the most basic form of matter, then what is an atom? It’s the smallest particle of an element that has properties of that element. Every atom is made up of protons, neutrons and electrons. Atoms have a nucleus, which is the center of the atom and that’s filled with protons and neutrons. The electrons surround the nucleus. Protons have a positive electrical charge, Electrons have a negative electrical charge and neutrons are electrically neutral.

Compounds

However, there’s more in nature than just the elements. As we’ve already talked about, elements can combine to form different matter – element Hydrogen and element Oxygen can combine to form water. This is called a compound. Other examples of compound are carbon dioxide, table salt and rust. Just like an atom is the smallest part of an element, a molecule is the smallest part of a compound. When atoms combine to form compounds, they are held together by a chemical bond.

Chemical symbols represent elements (He is Helium). Chemical formulas represent compounds (H2O is water. That means one molecule of water has 2 Hydrogen atoms and 1 Oxygen atom.