1. Atoms and Molecules

2. Atoms Atoms are the smallest particles of matter
Matter is anything that takes up space and has mass
Atoms consists of three types of parts: protons, neutrons and electrons
The centre of an atom is called the nucleus. In that nucleus we find the protons and neutrons

3. The electrons are found in orbits outside the nucleus
Each type of atom has a special number of protons. This is what makes the difference between 2 types of atoms or elements
Example: Page of textbook- find Aluminum and Calcium

4. Aluminum has the chemical symbol Al and contains 13 protons, which is what makes it 13th in the periodic table
Calcium has 20 protons and is 20th in the table
The different number of protons will change the properties of these two different metals

5. Protons are positively charged and have a mass of 1 amu
Amu stand for atomic mass unit
Neutrons do not carry any charge and also have a mass of 1 amu
Electrons have a negative charge and almost no mass. We describe this type of mass as negligible

6. Most matter is electronically neutral since protons carry a positive charge and electrons a negative one, they cancel each other out
Atoms join together in different combinations to form what we call molecules