Atoms and Molecules

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

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 206-207 of textbook- find Aluminum and Calcium

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

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

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