C2

- Atoms consist of electrons surrounding a nucleus that contains protons and neutrons.

- The number of protons in an atom is called its atomic number.

- Electrons are arranged in energy levels or shells, and different energy levels can hold different numbers of electrons.

- Proton = Mass 1; charge +1; Location - Nucleus

- Neutron = Mass 1; Charge 0; Location - Nucleus

- Electron = Mass 1/2000; Charge -1; Location - Orbiting the Nucleus

- Elements consists of one type of atom only

- Compounds are chemically bonded, and they are formed when 2 more elements react together - chemically.

- It is important to note that its difficult to seperate the 2 original elements out again.

- Isotopes are different atomic forms of the same elements, which have the SAME number of protons but a DIFFERENT number of neutrons.

- Vertical Columns of the periodic table are called groups.

- Horizontal Rows are called periods.

- Group 1 elements are called alkali metals.

- Group 7 elements are called halogens.

- Group 0 elements are called noble gases.