2. Electrons Chemistry Dr. May

3. Atomic Inventory Protons (Atomic Number) Neutrons (Atomic Mass minus Protons) Electrons (Same number as protons)

4. Atomic Particles ParticleLocationMass in amu Charge Proton Neutron Electron nucleus cloud 1 1 0 + 1 0  1

5. Electron Function Only the electrons of an atom are involved in chemical reactions Only the electrons in the outermost orbital are involved in chemical reactions

6. Outermost Electrons Atoms have between 1 and 8 electrons in the outermost orbital These electrons are called valence electrons Only valence electrons are involved in chemical reactions

7. Electron Distribution and Configuration Atom 1s2s 2p3s 3p4s Ca - 40  EC 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2

8. Electron Configuration Krypton –1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 Sodium –1s 2 2s 2 2p 6 3s 1 Chlorine –1s 2 2s 2 2p 6 3s 2 3p 5

9. Reading Electron Configurations Krypton - 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 The large numbers are the orbitals and in the known elements can go from 1 to 7

10. Reading Electron Configurations Krypton - 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 The letters s,p,and d represent the suborbitals The fourth letter f is not used in Kr

11. Suborbitals The suborbitals (s,p,d and f) are named after lines in the electromagnetic spectrum: s = sharp p = principle d = diffuse f = fundamental

12. Metal Salts Burning

13. Reading Electron Configurations Krypton - 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 The superscript or exponent (2p 6 ) represents the number of electrons in each suborbital Kr has 6 electrons in the 2p

14. Valence Electrons Krypton - 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 has 8 valence electrons Sodium - 1s 2 2s 2 2p 6 3s 1 has 1 valence electron Chlorine - 1s 2 2s 2 2p 6 3s 2 3p 5 has 7 valence electrons

15. Element 118 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6 7s 2 5f 14 6d 10 7p 6 Element 118 (ununoctium) (Uuo) Has 118 electrons Has 8 valence electrons Is an inert gas Was discovered at Berkley in 1999

16. Valence Electrons Sum of the outermost s an p electrons Na = 1 Ca = 2 Al = 3 C = 4 N = 5 O = 6 Cl = 7 Ne = 8

17. Oxidation Number Number of valence electrons lost (+) or gained (–) during a chemical reaction Na = (1) +1 Ca = (2) +2 Al = (3) +3 C = (4) +4 or –4 N = (5) +5 or –3 O = (6) –2 Cl = (7) –1 Ne = (8) 0

18. Distribution Of Sodium atom 1s2s 2p3s 3p4s Na - 11  

19. Distribution Of Sodium Ion ion 1s2s 2p3s 3p4s Na +1  X

20. Distribution Of Chlorine atom 1s2s 2p3s 3p4s Cl - 17  

21. Distribution Of Chloride Ion ion 1s2s 2p3s 3p4s Cl  1  

22. Opposite Charges Attract

23. The End This presentation was created for the benefit of our students by the Science Department at Howard High School of Technology Please send suggestions and comments to rmay@nccvt.k12.de.us