An atom is the smallest particle of an element that contains protons, neutrons, and electrons. Elements are substances made of a single type of atom that combine to form molecules, which are made of two or more atoms joined together. Molecules such as water, written as H2O with two hydrogen atoms and one oxygen atom, are the smallest particles that combine without chemical change to form all matter in the world.

1. Physical Science Atoms, Molecules, and Matter

2. What is an Atom? An atom is the smallest particle of an element that has all the properties of that element. Atoms are the building blocks of elements.

3. Structure of Atoms Nucleus – the nucleus contains neutrons (no charge) and protons (positive charge). Electrons – tiny particles surrounding the nucleus (negative charge).

4. What is an element? An element is a substance that cannot be broken down any further. They are the building blocks of matter. Elements combine to make the world around us. There are only a few elements found alone in nature: Ex: Silver and Gold

6. What are molecules? Molecules are the smallest particles that can be divided without chemical change. They are made of two or more atoms joined together, can be the same element or different elements. A molecule of water is written H 2 O. This means there are 2 atoms of hydrogen and one atom of oxygen.

7. H H O

8. ATOMS Elements Molecules Matter H 2 O H H O