1. Atomic Structure

2. History  400 B.C. – Democritus proposed all matter was made up of small particles called atoms  Atomic numbers were assigned to elements by Henry Moseley  1913- Niels Bohr described the planetary model of the atom

3. Planetary model

4. The Shell Model  The more accurate model puts a cloud around the nucleus and electrons move about in shells  Each shell can hold so many electrons  Little energy in the most inner shell so only 2 electrons can be found there.  The farther you get from the nucleus, the more electrons a shell can hold

5. The atoms makeup  This shell model of a hydrogen atom or lead atom is made up of the same general parts.  A nucleus made up of protons (1 in Hydrogen and 82 in Lead) and neutrons (usually the same amount as the protons)  Floating around the nucleus are electrons

6. Mass of Subatomic Particles ParticleCharge Mass compared Actual Mass to electron ElectronNegative 19.11x10 -31 ProtonPositive 18361.673x10 -27 Neutron Neutral 18411.675x10 -27

7. Charges  The three subatomic particles as they are called have different charges  Protons- (+)  Neutrons- no charge  Electrons- (-)

8. 

10. Atomic Mass  The mass of an atom is equal to the number of protons and neutrons found in the nucleus  If an atom of carbon has 6 protons and 6 neutrons, its mass is 12

11. Atomic Number  The atomic number found above the chemical symbol is equal to the number of protons the atom has  An atom with 19 protons has to be potassium (K)

12. Chemical Names  Why is Co different from CO?  Co is Cobalt  CO is carbon monoxide  Be sure to use upper and lower case properly

13. Isotopes  Atoms of the same element that have different numbers of neutrons are called isotopes  Hydrogen can have 0, 1, or 2 neutrons in it’s nucleus

14. Misc. Facts  Hydrogen is the most abundant element. It makes up almost 90% of all atoms. As well it was the 1 st element to exist  Fused hydrogen atoms formed inside stars and this created the other elements  Most atoms formed when the universe began and are constantly being recycled  Atoms that make up ‘you’ are billions of years old

15. Names w/ 1 letter that begins name Names w/ 2 letters and both letters are start of name Names w/ 2 letters and 1 st letter starts and second is heard later in name Symbol has nothing to do with name CarbonNeonMagnesiumSodium

16. Chapter Review (class work)  Try to complete #5, 6, and 7.

17. Protons have a positive charge A. True B. False

18. C-12 is a radioactive isotope used in carbon dating fossils A. True B. False

19. The charge of a neutron is A. negative B. No charge

20. The number of electrons that can fit in the 1 st shell is A. 8 B. 2 C. 18

21. The electron has more mass than the proton and neutron A. Yes B. No

22. The atomic number of carbon is A. 12.01115 B. 12 C. 6 D. C

23. The element symbol of helium is A. H B. 2 C. He D. Helium

24. The mass number of C-14 is 14 A. True B. False

25. Play-doh Lab  Partner up  Create a 3 dimensional model of an atom using play-doh and beads. It must be the shell model  Your atom must have an atomic number between 6 and 12.  On a separate sheet draw your atom and label the following: Protons, neutrons, electrons, nucleus, electron cloud, any and all shells  Write down the name, atomic number, atomic mass, and symbol