Chemistry topic 1!

• An element is a substance made up of atoms that all have the same number of protons in their nucleus.
• Isotopes are different forms of the same element, which have the same number of protons but a different number of neutrons
• Protons have a relative charge of +1. Neutrons have a relative charge of 0 and electrons have a relative charge of -1.
• Atomic number = Number of protons
• Mass number = Number of protons + number of neutrons