1. Topic 2/12 Overview 2.2: Electron configuration 2.1: The Nuclear Atom
12.1: Electrons in Atoms

2. Continuous Spectrum

3. Bright-line (emission) Spectra

4. Hydrogen’s Line Spectrum

5. Data Booklet and Light Info

6. Light as a Wave λ m or nm ν 1/s = s-1 = Hz Properties Def. Symbol
Units
Wavelength λ
m or nm
Frequency ν
1/s = s-1 = Hz

7. Frequency (f) increases
Wavelength (λ) increases
Frequency (f) increases

8. Sample light and energy calculation
An FM radio station broadcasts at 95.1 MHz.
Calculate the wavelength and identify the type of radiation using Table 3.
Determine the energy of a photon this radiation.

9. Sample light and energy calculation
An FM radio station broadcasts at 95.1 MHz.
Calculate the wavelength and identify the type of radiation using Table 3.
95.1 MHz = 9.51 x 107 1/s
λ = c/ν = 3.15 m
Determine the energy of a photon this radiation.
E = hν = 6.31 x J

10. Learning Check
An excited atom gives off a photon of light with a wavelength of nm. Find its frequency and energy.

11. Learning Check
An excited atom gives off a photon of light with a wavelength of nm. Find its frequency and energy.
(λ= x 10-7m)
ν = 6.89 x 1014 s-1
E = 4.57 x J

12. The Bohr Model of the Atom

13. Energy level transitions

14. Energy level transitions

15. Energy level transitions
Event
Description
Excitation:
An electron moves to a higher energy level.
Absorption:
Atom takes in energy from heat, light, or electricity (moving electrons).
Emission:
The atom releases a photon of light with a wavelength determined by the the size of the energy difference between the two levels of the transition.
Relaxation:
An electron returns from a higher energy to a lower energy level.

17. Balmer series (visible) e- drop into the n = 2
Lyman series (ultraviolet) e- drop into the n = 1
Paschen series (infrared) e- drop into the n = 3

18. Convergence
As n becomes larger, the spacing between neighboring levels decreases
Energy levels in H atom converge at higher energies & shorter λ as n → ∞.

19. Significance of Convergence
Convergence limit (def.)- the wavelength at which the discrete lines in the spectrum merge into a continuum as n → ∞.

20. Significance of Convergence
The convergence limit corresponds to the energy required to completely remove the electron from the atom, a.k.a its ionization energy.

21. Calculation of Ionization Energy from Convergence Limit
Sample problem:
Calculate the ionization energy of hydrogen (in kJ mol-1) given that the convergence limit occurs at 91.2 nm. Compare answer with Data Booklet.

22. Write a equation of the ionization energy of helium. [2]
Learning Check
Blank sheet, open notes. Show ALL work, formulas, etc. BOX answers. Use UNITS and SIG FIGS. Independent.
Write a equation of the ionization energy of helium. [2]
Given that the convergence limit of helium is 50.4 nm, calculate the
frequency of the convergence limit [1]
ionization energy (in kJ mol-1) [2]

23. Some definitions Ionization enthalpy, IE
energy change when 1 mol of e- removed from 1 mol of atoms in the gas phase

24. Ionization Energies and your Data Booklet

25. MCQ Which equation represents the first ionization energy of calcium?
A. Ca(g) →Ca+(g) + e–
B. Ca(g) →Ca–(g) + e–
C. Ca(g) + e– → Ca–(g)
D. Ca+(g) + e– → Ca(g)
E. Ca(g) → Ca2+(g) + 2e–

26. Why is energy needed to ionize an atom?

27. Ionization Energy (a.k.a 1st IE)
Amount of energy needed to remove 1 mol of electrons from 1 mole of atoms in the gaseous state.

28. Successive Ionization Energy
Successive - one after another, sequential
(IE1, IE2, IE3, IE4,...etc.)

29. Successive Ionization Energy
2nd ionization energy (IE2) - energy required to remove a 2nd mole of e- from the ions produced by the loss of 1 e-.

30. Successive Ionization Energy
2nd ionization energy (IE2) - energy required to remove a 2nd mole of e- from the ions produced by the loss of 1 e-.
IE1:
IE2:

31. MCQ
Which equation represents the third ionization energy for an atom of phosphorus?
A. P(g) → P3+(g) + 3e-
B. P2+(g) → P3+(g) + e-
C. P3+(g) → P4+(g) + e-
D. P3+(g) + e- → P2+(g)
E. P(g) + 3e- → P3-(g)

32. Why is IE1 < IE2 < IE3 < ...?
Be → Be+ + e-
Be+ → Be e-

35. Discontinuities in 1st IE graph

36. Simple Rule
If atom has n valence electrons, it will have a large “jump” at IEn+1.

41. FRQ
The graph represents the energy needed to remove nine electrons, one at a time, from an atom of an element. Not all of the electrons have been removed. Which element could this be?

42. Actual electron configs

44. Hydrogen’s Ionization Energy

45. Helium’s Ionization Energy

46. Lithium’s Ionization Energy

47. Lithium’s Ionization Energy

48. Beryllium’s Ionization Energy

49. FRQ
Complete the “Trends in 1st IE Activity” on the website. After graphing the IE for the 1st 20 elements, answer the question:
What do you think are some possible claims we can make about the arrangement of electrons in atoms based on the patterns in IE’s?

50. IE trends and energy level model

52. Energy level model of the atom
Evidence from 1st IE’s reveals an electronic shell structure of:

53. IE trends and energy level model
The presence of a decrease in IE from
atomic #2 to #3
atomic #10 to #11
atomic #18 to #19
suggests
a) that there is an abrupt change in distance of the electron being removed (i.e. energy levels)

54. IE trends and energy level model
b) that the electron arrangement per energy level is:
n = 1 2 e- max
n = 2 8 e-max
n = 3 8 e- max

55. IE and sublevels
Irregular pattern of increase indicates that not all e- in energy level have the same energy.
Provides evidence for existence of energy sublevels.