Rutherford discovered that the atom has a small, dense nucleus at its center, changing the old atomic model. Niels Bohr is most responsible for the current atomic model, which uses quantum mechanics to describe electrons orbiting the nucleus in shells and subshells based on their energy levels. Electrons fill these orbitals according to specific rules.

1. OBE H. Chemistry 2/9/11 What did Rutherford discover about the atom that changed the old atomic model? Who is “most responsible for the current model of the atom?

3. Electronic Configuration according to Quantum Mechanics The location of an electron is described by 3 terms. 1 st Term: Shell ( n ) n = 1 n = 2 n = 3 lone electron of Hydrogen

5. 2 nd Term: subshell - designated by s, p,d,f 1 s n = 2 n = 3 The first shell ( 1 ) has one subshell ( s ).

6. 2 nd Term: subshell - designated by s, p,d,f - refers to the shape(s) of the area in which the electron can be located. - also designates an energy level within the shell. 1 s n = 2 n = 3 The first shell ( 1 ) has one subshell ( s ). The s subshell is s pherical in shape and has 1 orbital 3rd Term: orbital

7. 2 nd Term: subshell - designated by s, p,d,f - refers to the shape(s) of the area in which the electron can be located. - also designates an energy level within the shell. 1 s n = 2 n = 3 The first shell ( 1 ) has one subshell ( s ). The s subshell is s pherical in shape and has 1 orbital 3rd Term: orbital Each orbital can accommodate 2 electrons

8. The Electronic Configuration of Hydrogen 1 s The first shell ( 1 ) has one subshell ( s ). The s subshell is s pherical in shape and has 1 orbital H 1 s 1 shell subshell # of electrons present energy H 1 s  Electronic configuration Orbital Energy Level Diagram

9. The Electronic Configuration of Helium He: Atomic # of 2, 2 electrons in a neutral He atom 1 s

10. The Electronic Configuration of Helium He: Atomic # of 2, 2 electrons in a neutral He atom H 1 s 1 He 1 s 2 He 1 s  1 s **if there are 2 electrons in the same orbital they must have the opposite spin. (Pauli’s Exclusion Principle)

12. 1 s The Electronic Configuration of Lithium (Li) Li: Z =3 Li has 3 electrons. 2 nd shell (2)

13. 1 s The Electronic Configuration of Lithium (Li) Li: Z =3 Li has 3 electrons. 2 nd shell - The 2nd shell ( n = 2 ) has 2 subshells which are s and p . 2 s 2 p

14. 1 s The Electronic Configuration of Lithium (Li) Li: Z =3 Li has 3 electrons. 2 nd shell 2 s 2 p Li 1 s 2 2 s 1 2 s  Li 1 s  Electronic configuration Orbital Energy Level Diagram

15. 1 s The Electronic Configuration of Berylium (Be) Be: Z =4 Be has 4 electrons. 2 nd shell 2 s 2 p Be 1 s 2 2 s 2 2 s  Be 1 s  Electronic configuration Orbital Energy Level Diagram 

17. subshell - designated by s, p,d,f - refers to the shape(s) of the area in which the electron can be located. - also designates an energy level within the shell. - relative energy: s < p < d < f s subshell: s pherical 1 orbital p subshell: p air of lobes x y z x y z

18. Our Orbital Picture of Be The first shell ( 1 s ) is filled. The 2 s orbital has 2 e - present. The 2 p orbitals are empty. The 2 p orbitals have room for 6 e -

20. 1 s The Electronic Configuration of Boron (B) B: Z =5 B has 5 electrons. 2 nd shell 2 s 2 p 1 s 2 nd shell 2 s 2 p Be 1 s 2 2 s 2 2 s  Be 1 s  B 1 s 2 2 s 2 2 p 1 2 p  2 s  B 1 s 

21. H Chem OBE 2/14/11 Create the following drawing in your notes that shows the electron filling order!

22. 1 s The Electronic Configuration of Carbon (C) C: Z =6 C has 6 electrons. 2 nd shell 2 s 2 p 1 s 2 nd shell 2 s 2 p B 1 s 2 2 s 2 2 p 1 2 p  2 s  B 1 s  C 1 s 2 2 s 2 2 p x 1 p y 1 2 p   2 s  C 1 s 

23. Our Orbital Picture of C The first shell ( 1 s ) is filled. The 2 s orbital has 2 e - present. 2 2 p orbitals have 1 e - each.

25. d subshell: double dumbells xy z 2 xz x y yz x 2- y 2

28. Atomic Radii within a Group Lithium (Z=3); n = 2 Sodium (Z=11); n = 3 Hydrogen (Z=1); Shell (n)=1 + + + e - 2e - 8e - 2e - + + + + e - + e -

29. Lithium (Z=3) n = 2 Beryllium (Z=4) n = 2 Boron (Z=5) n = 2 If protons were light bulbs….and electrons were moths…... + + + e - 2e - + + + e - 2e - e - + + + + e - 2e - e - e - + + B e - e - e - Be e - e - Li e - + + + e - 2e - + + + e - 2e - e - +

30. Lithium (Z=3) Beryllium (Z=4) Boron (Z=5)  Increasing  Increasing + + + e - 2e - + + + e - 2e - e - + + + + e - 2e - e - e - + +

32. H. Chemistry OBE 2/16/11 Of the elements Mg, Cl, Na, and P which would have the largest atomic radius? Explain this in terms of trends in the periodic table (periodicity). + + + e - 2e - + + + e - 2e - e - + + + + e - 2e - e - e - + +

33. First Ionization Energy Lithium (Z=3) Sodium (Z=11) Hydrogen (Z=1) + e - + + + e - 8e - 2e - + + + + e - + e - H + + + + e - 2e - Li + e - 8e - 2e - + + + + Na +

34. First Ionization Energy e - Lithium (Z=3) 8e - Sodium (Z=11) 2e - 2e - e - Hydrogen (Z=1) e -  Decreasing + + + + + + + +

35. Lithium (Z=3) 3 protons screened by 2 e - e - 2e - Beryllium (Z=4) 4 protons screened by 2 e - Boron (Z=5) 5 protons screened by 2 e - e - 2e - e - e - 2e - e - e - 1 e - removed = 2s 0 1 e - removed = 2s 1 1 e - removed = 2s 2 2p 0 + + + + + + + + + + + +  Decreasing  Decreasing

36. Lithium (Z=3) 3 protons screened by 2 e - e - 2e - Beryllium (Z=4) 4 protons screened by 2 e - Boron (Z=5) 5 protons screened by 2 e - e - 2e - e -  Decreasing  Decreasing + + + + + + + + + + e - 2e - e - e - + +

37.  Increasing  Increasing Trends in the Periodic Table Atomic Radii (Size) First Ionization Energy  Decreasing  Decreasing

38. Electron Affinity e - Fluorine (Z=9) 8e - Chlorine (Z=17) 2e - 2e - 7e - 7e - 2e - 8e - F - e - 8e - 2e - 8e - Cl - + + + + + + + + + + + + + +

39. Trends in the Periodic Table First Ionization Energy  Decreasing  Decreasing  Decreasing  Decreasing Electron Affinity

40. Predicting Stable Ions 8e - Sodium (Z=11) 2e - e - e - 8e - 2e - Na + 8e - Chlorine (Z=17) 2e - 7e - e - 8e - 2e - 8e - Cl - + + + + + + + + + + + + + + + +