1. Is a basic unit of MATTER. Atoms are made up of PROTONS, ELECTRONS and NEUTRONS.

2. t h e P OS I T I V E L Y CHARGE D. T h e proton is a s u b a t o m i c a r t i c l e with the symbol p or p + d a positive e l e c t r i c c h a r g e of 1 e l e m e n t a r y c h a r g e . .

3. Ar e NE GAT I V E L Y CHARGE D p a r t i a r e i n c o n s t a n t mo t i o n i n s pa c e a r ound t he nuc l e u

4. i n t h e c e n t r e o f a n a t o m a n d i t s ma d e u p o f Pr ot ons a n d e l e c t r ons .

5. Is a pure substance that consist of one type of atom. There are over 100 known elements while only about 24 are commonly found in living organisms.

6. The mass number is the sum of the PROTONS and Neutrons in an ATOMS nucleus. Can be identified by its mass number