Chemistry 2

C

hemistry 2 Exam- revision.

Looking more closely at the atom

Structure of the atom

. Atoms have a central nucleus made of protons and neutrons.

. Around the centre nucleus are electrons.

. Protons have a charge of +1; electrons have a charge of -1; neutrons are neutral (a charge of 0).

. Atoms always have the same number of protons as electrons. This is why they are always neutral.

. The number of protons an atom has is called its atomic (Proton) number.

Where do electrons go?

. Electrons occupy particular energy levels (or shells).

. Electrons always occupy the lowest possible energy level avalible (the shell closes…