Atoms, Elements + Compounds

Atoms, Elements + Compounds

1. Atomic Number = no. of protons

2. Mass number = no. of protons + no. of neutrons

3. Isotopes - different atoms with same no. of protons but diff. no. of neutrons in the nucleus

   • Identical chemical properties
   • Slightly different physical properties

4. Ar = total mass/total no. of atoms

5. Element - Pure substance, contains only one type of atoms and can not be broken down into any simpler substance by chemical means

6. Mixture - Two or more substances mixed together, not chemically combined and can be separated by physical means

7. Compound - Two or more elements chemically combined, can not be separated by physical means

8. Molecules - contain a certain fixed no. of atoms joined together by covalent bonds

9. Mass no. > Atomic no.