1. ATOMS! W HAT ’ S IN THEM ?

2. P ARTS OF THE A TOM A TOMS CONTAIN A NUCLEUS AND AN ELECTRON CLOUD. NucleusElectron Cloud

3. N UCLEUS … WHAT ’ S IN IT ? T HE NUCLEUS HAS THE P ROTONS & N EUTRONS

4. E LECTRON C LOUD … WHAT ’ S IN IT ? T HE ELECTRONS !

5. H OW DO YOU KNOW ? H OW DO YOU KNOW HOW MANY PROTONS ARE IN AN ATOM ? P ROTONS = T HE ATOMIC NUMBER ( FROM THE PERIODIC TABLE ) A TOMIC NUMBER A TOMIC W EIGHT

6. L ET ’ S CHECK … H OW MANY PROTONS DOES CHLORINE HAVE ? C HLORINE HAS 17 PROTONS H OW MANY PROTONS DOES ARSENIC HAVE ? A RSENIC HAS 33 PROTONS

7. H OW DO YOU KNOW ? H OW DO YOU KNOW HOW MANY ELECTRONS ARE IN AN ATOM ? E LECTRONS = T HE ATOMIC NUMBER ( SAME AS PROTONS !)

8. L ET ’ S CHECK … H OW MANY ELECTRONS DOES CHLORINE HAVE ? C HLORINE HAS 17 ELECTRONS H OW MANY ELECTRONS DOES CHROMIUM HAVE ? C HROMIUM HAS 24 ELECTRONS

9. H OW DO YOU KNOW ? H OW DO YOU KNOW HOW MANY NEUTRONS ARE IN AN ATOM ? N EUTRONS = A TOMIC W EIGHT – A TOMIC N UMBER S ODIUM HAS 12 NEUTRONS (23-11) A TOMIC W EIGHT

10. L ET ’ S C HECK … H OW MANY NEUTRONS DOES C OBALT HAVE ? C OBALT HAS 59-27 = 32 NEUTRONS H OW MANY NEUTRONS DOES L ITHIUM HAVE ? L ITHIUM HAS 7-3 = 4 NEUTRONS

11. L ET ’ S REVIEW … H OW MANY PROTONS DOES M ERCURY HAVE ? M ERCURY HAS 80 PROTONS M ERCURY HAS 201-80 = 121 NEUTRONS H OW MANY ELECTRONS DOES M ERCURY HAVE ? M ERCURY HAS 80 ELECTRONS H OW MANY NEUTRONS DOES M ERCURY HAVE ?

12. What is the purpose of protons? The number of protons tells you the identity of the element. For example… you know that something has 24 protons in the nucleus, that means it is CHROMIUM! Remember, the protons are located in the nucleus.

13. Protons… The number of protons also tells you the properties of the element. For example… because calcium has 20 protons, it is a white, malleable, shiny, metal element. Finally, protons are part of the atomic weight (mass).

14. Protons… Determines Identity? Determines Properties? Determines Atomic Weight? Determines Charge? ProtonsYes No Electrons Neutrons

15. What is the purpose of electrons? The number of electrons tells you how the atom will bond with other elements. Remember, they are located in the electron cloud.

16. Electrons… When an element bonds with another, it exchanges electrons. (for example H 2 + O 2 -> H 2 O) When this atom exchanges electrons, it becomes charged. Then, it is called an ion.

17. Electrons… Determines Identity? Determines Properties? Determines Atomic Weight? Determines Charge? ProtonsYes No ElectronsNo Yes Neutrons determine the CHARGE of an atom. (when it is ionic!)

18. What is the purpose of neutrons? The number of neutrons tells you the isotope of the element. For example… Carbon-12 = diamonds Carbon-13 = medicine Carbon-14 = fossil dating

19. Neutrons… Determines Identity? Determines Properties? Determines Atomic Weight? Determines Charge? ProtonsYes No ElectronsNo Yes NeutronsNo YesNo And, neutrons are the other part of the atomic weight. Remember, the neutrons are located in the nucleus.