CHEMISTRY UNIT 1

FUNDAMENTAL IDEAS IN CHEMISTRY

ATOMS AND THE PERIODIC TABLE

• all substances are made from atoms
• a substance made of one type of atom is an element
• a substance made from a mixture of atoms is a compound
• there are 100 elements approximately known and in the Periodic Table
• The different groups in the Periodic Table contain elements with similar properties
• an atoms nucleus contains protons and neutrons
• around the atom in the outer shells are electrons
• group number = number of electrons in outer shell. This gives them similar properties
• protons - positive
• neutrons - neutral
• electrons - negative
• number of protons = number of neutrons
• …