1. 1.Draw a dot-cross diagram for a sodium atom 2.Write an equation to show the first ionisation energy of sodium (its value is +496kJmol -1 ) 3.Write an equation to show the fifth ionisation energy of sodium (+13352kJmol -1 ) 4.Why are they such different values? (3 main factors) How much can you remember from last lesson?

2. To Learn Today What are electron orbitals? What are shells and sub-shells? What is the principal quantum number? How can we write electron configurations? How are they all related to the periodic table?

3. THE BOHR ATOM Maximum electrons per shell 1st shell 2 2nd shell 8 3rd shell 18 4th shell 32 5th shell 50 Energy Levels increase further from the nucleus

4. 1 2 3 4 INCREASING ENERGY / DISTANCE FROM NUCLEUS Shells of Electrons PRINCIPAL ENERGY LEVELS Hydrogen was studied The gaps between energy levels were not equal The closer to the nucleus, the closer together the energy levels were

5. HEISENBERG’S UNCERTAINTY PRINCIPLE “You cannot determine the position and momentum of an electron at the same time.” This means that you cannot say exactly where an electron is. It put paid to the idea of electrons orbiting the nucleus in rings and introduced the idea of orbitals.

6. Sketch a probability cloud for the football on the pitch

7. 1 2 3 4 INCREASING ENERGY / DISTANCE FROM NUCLEUS LEVELS AND SUB-LEVELS A study of Ionisation Energies and the periodic properties of elements suggested that the main energy levels were split into sub shells. Level 1 was split into 1 sub shell Level 2 was split into 2 sub shells Level 3 was split into 3 sub shells Level 4 was split into 4 sub shells SUB SHELLS PRINCIPAL SHELLS

8. RULES AND PRINCIPLES THE AFBAU PRINCIPLE “Electrons enter the lowest available energy level.” PAULI’S EXCLUSION PRINCIPLE “No two electrons can have the same four quantum numbers.” Two electrons can go in each orbital, providing they are of opposite spin. HUND’S RULE OF MAXIMUM MULTIPLICITY “When in orbitals of equal energy, electrons will try to remain unpaired.” “SITTING ON A BUS RULE”!

9. ATOMIC ORBITALS An orbital is... a region in an ATOM that can hold up to TWO ELECTRONS, with OPPOSITE SPINS

10. ORBITALS a region in space where one is likely to find an electron. An orbital is... a region in space where one is likely to find an electron. Orbitals can hold up to two electrons as long as they have opposite spin; this is known as PAULI’S EXCLUSION PRINCIPAL. Orbitals have different shapes... ORBITAL SHAPE OCCURRENCE ssphericalone in every principal level pdumb-bellthree in levels from 2 upwards dvariousfive in levels from 3 upwards fvariousseven in levels from 4 upwards

11. ORBITALS a region in space where one is likely to find an electron. An orbital is... a region in space where one is likely to find an electron. Orbitals can hold up to two electrons as long as they have opposite spin; this is known as PAULI’S EXCLUSION PRINCIPAL. Orbitals have different shapes... ORBITAL SHAPE OCCURRENCE ssphericalone in every principal level pdumb-bellthree in levels from 2 upwards dvariousfive in levels from 3 upwards fvariousseven in levels from 4 upwards An orbital is a 3-dimensional statistical shape showing where one is most likely to find an electron. Because, according to Heisenberg, you cannot say exactly where an electron is you are only able to say where it might be found. DO NOT CONFUSE AN ORBITAL WITH AN ORBIT

12. SHAPES OF ORBITALS s orbitals spherical one occurs in every principal energy level s = ‘sharp’

13. SHAPES OF ORBITALS p orbitals dumb-bell shaped three occur in energy levels except the first p = ‘principal’

14. SHAPES OF ORBITALS d orbitals various shapes five occur in energy levels except the first and second d = ‘diffuse’

15. Orbitals are not filled in numerical order because the principal energy levels get closer together as you get further from the nucleus. This results in overlap of sub levels. The first example occurs when the 4s orbital is filled before the 3d orbitals. INCREASING ENERGY / DISTANCE FROM NUCLEUS 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f PRINCIPAL ENERGY LEVELS SUB LEVELS ORDER OF FILLING ORBITALS

16. Orbitals are not filled in numerical order because the principal energy levels get closer together as you get further from the nucleus. This results in overlap of sub levels. The first example occurs when the 4s orbital is filled before the 3d orbitals. INCREASING ENERGY / DISTANCE FROM NUCLEUS 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f PRINCIPAL ENERGY LEVELS SUB LEVELS 1 1s 2 2s 2p 3d 3 3s 3p 4s 4 4p 4d 4f PRINCIPAL ENERGY LEVELS SUB LEVELS ORDER OF FILLING ORBITALS

17. Orbitals are not filled in numerical order because the principal energy levels get closer together as you get further from the nucleus. This results in overlap of sub levels. The first example occurs when the 4s orbital is filled before the 3d orbitals. INCREASING ENERGY / DISTANCE FROM NUCLEUS 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f PRINCIPAL ENERGY LEVELS SUB LEVELS 1 1s 2 2s 2p 3d 3 3s 3p 4s 4 4p 4d 4f PRINCIPAL ENERGY LEVELS SUB LEVELS ORDER OF FILLING ORBITALS THE FILLING ORDER 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 7s 7p HOW TO REMEMBER...

18. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS This states that… “ELECTRONS ENTER THE LOWEST AVAILABLE ENERGY LEVEL” THE ‘AUFBAU’ PRINCIPAL The following sequence will show the ‘building up’ of the electronic structures of the first 36 elements in the periodic table. Electrons are shown as half headed arrows and can spin in one of two directions or s orbitals p orbitals d orbitals

19. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS HYDROGEN 1s 1 THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS Hydrogen atoms have one electron. This goes into a vacant orbital in the lowest available energy level. ‘Aufbau’ Principle ‘Aufbau’ Principle

20. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS HELIUM 1s 2 THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS Every orbital can contain 2 electrons, provided the electrons are spinning in opposite directions. This is based on... PAULI’S EXCLUSION PRINCIPLE The two electrons in a helium atom can both go in the 1s orbital. ‘Aufbau’ Principle ‘Aufbau’ Principle

21. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS LITHIUM 1s orbitals can hold a maximum of two electrons so the third electron in a lithium atom must go into the next available orbital of higher energy. This will be further from the nucleus in the second principal energy level. The second principal level has two types of orbital (s and p). An s orbital is lower in energy than a p. 1s 2 2s 1 ‘Aufbau’ Principle ‘Aufbau’ Principle

22. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS BERYLLIUM Beryllium atoms have four electrons so the fourth electron pairs up in the 2s orbital. The 2s sub level is now full. 1s 2 2s 2 ‘Aufbau’ Principle ‘Aufbau’ Principle

23. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS BORON As the 2s sub level is now full, the fifth electron goes into one of the three p orbitals in the 2p sub level. The 2p orbitals are slightly higher in energy than the 2s orbital. 1s 2 2s 2 2p 1 ‘Aufbau’ Principle ‘Aufbau’ Principle

24. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f HUND’S RULE OF MAXIMUM MULTIPLICITY HUND’S RULE OF MAXIMUM MULTIPLICITY INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS CARBON The next electron in doesn’t pair up with the one already there. This would give rise to repulsion between the similarly charged species. Instead, it goes into another p orbital which means less repulsion, lower energy and more stability. 1s 2 2s 2 2p 2

25. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS HUND’S RULE OF MAXIMUM MULTIPLICITY HUND’S RULE OF MAXIMUM MULTIPLICITY NITROGEN Following Hund’s Rule, the next electron will not pair up so goes into a vacant p orbital. All three electrons are now unpaired. This gives less repulsion, lower energy and therefore more stability. 1s 2 2s 2 2p 3

26. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS OXYGEN With all three orbitals half- filled, the eighth electron in an oxygen atom must now pair up with one of the electrons already there. 1s 2 2s 2 2p 4 ‘Aufbau’ Principle ‘Aufbau’ Principle

27. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS FLUORINE The electrons continue to pair up with those in the half-filled orbitals. 1s 2 2s 2 2p 5

28. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS NEON The electrons continue to pair up with those in the half-filled orbitals. The 2p orbitals are now completely filled and so is the second principal energy level. In the older system of describing electronic configurations, this would have been written as 2,8. 1s 2 2s 2 2p 6

29. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS SODIUM - ARGON With the second principal energy level full, the next electrons must go into the next highest level. The third principal energy level contains three types of orbital; s, p and d. The 3s and 3p orbitals are filled in exactly the same way as those in the 2s and 2p sub levels. ‘Aufbau’ Principle ‘Aufbau’ Principle

30. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS SODIUM - ARGON Na 1s 2 2s 2 2p 6 3s 1 Mg 1s 2 2s 2 2p 6 3s 2 Al 1s 2 2s 2 2p 6 3s 2 3p 1 Si 1s 2 2s 2 2p 6 3s 2 3p 2 P 1s 2 2s 2 2p 6 3s 2 3p 3 S 1s 2 2s 2 2p 6 3s 2 3p 4 Cl 1s 2 2s 2 2p 6 3s 2 3p 5 Ar 1s 2 2s 2 2p 6 3s 2 3p 6 Remember that the 3p configurations follow Hund’s Rule with the electrons remaining unpaired to give more stability.

31. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS POTASSIUM In numerical terms one would expect the 3d orbitals to be filled next. However, because the principal energy levels get closer together as you go further from the nucleus coupled with the splitting into sub energy levels, the 4s orbital is of a LOWER ENERGY than the 3d orbitals so gets filled first. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 ‘Aufbau’ Principle ‘Aufbau’ Principle

32. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS CALCIUM As expected, the next electron pairs up to complete a filled 4s orbital. This explanation, using sub levels fits in with the position of potassium and calcium in the Periodic Table. All elements with an -s 1 electronic configuration are in Group I and all with an -s 2 configuration are in Group II. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 ‘Aufbau’ Principle ‘Aufbau’ Principle

33. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS SCANDIUM With the lower energy 4s orbital filled, the next electrons can now fill the 3d orbitals. There are five d orbitals. They are filled according to Hund’s Rule - BUT WATCH OUT FOR TWO SPECIAL CASES. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 1 HUND’S RULE OF MAXIMUM MULTIPLICITY HUND’S RULE OF MAXIMUM MULTIPLICITY

34. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS TITANIUM 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2 HUND’S RULE OF MAXIMUM MULTIPLICITY HUND’S RULE OF MAXIMUM MULTIPLICITY The 3d orbitals are filled according to Hund’s rule so the next electron doesn’t pair up but goes into an empty orbital in the same sub level.

35. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS VANADIUM The 3d orbitals are filled according to Hund’s rule so the next electron doesn’t pair up but goes into an empty orbital in the same sub level. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 3 HUND’S RULE OF MAXIMUM MULTIPLICITY HUND’S RULE OF MAXIMUM MULTIPLICITY

36. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS CHROMIUM One would expect the configuration of chromium atoms to end in 4s 2 3d 4. To achieve a more stable arrangement of lower energy, one of the 4s electrons is promoted into the 3d to give six unpaired electrons with lower repulsion. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 5 HUND’S RULE OF MAXIMUM MULTIPLICITY HUND’S RULE OF MAXIMUM MULTIPLICITY

37. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS MANGANESE The new electron goes into the 4s to restore its filled state. HUND’S RULE OF MAXIMUM MULTIPLICITY HUND’S RULE OF MAXIMUM MULTIPLICITY 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 5

38. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS IRON Orbitals are filled according to Hund’s Rule. They continue to pair up. HUND’S RULE OF MAXIMUM MULTIPLICITY HUND’S RULE OF MAXIMUM MULTIPLICITY 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 6

39. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS COBALT HUND’S RULE OF MAXIMUM MULTIPLICITY HUND’S RULE OF MAXIMUM MULTIPLICITY 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 7 Orbitals are filled according to Hund’s Rule. They continue to pair up.

40. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS NICKEL HUND’S RULE OF MAXIMUM MULTIPLICITY HUND’S RULE OF MAXIMUM MULTIPLICITY 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 8 Orbitals are filled according to Hund’s Rule. They continue to pair up.

41. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS COPPER One would expect the configuration of chromium atoms to end in 4s 2 3d 9. To achieve a more stable arrangement of lower energy, one of the 4s electrons is promoted into the 3d. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 10

42. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS ZINC The electron goes into the 4s to restore its filled state and complete the 3d and 4s orbital filling. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10

43. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS GALLIUM - KRYPTON The 4p orbitals are filled in exactly the same way as those in the 2p and 3p sub levels. HUND’S RULE OF MAXIMUM MULTIPLICITY HUND’S RULE OF MAXIMUM MULTIPLICITY

44. 1 1s 2 2s 2p 4s 3 3s 3p 3d 4 4p 4d 4f INCREASING ENERGY / DISTANCE FROM NUCLEUS THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS GALLIUM - KRYPTON Ga - 4p 1 Ge - 4p 2 As- 4p 3 Se - 4p 4 Br - 4p 5 Kr - 4p 6 Remember that the 4p configurations follow Hund’s Rule with the electrons remaining unpaired to give more stability. Prefix with… 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10

45. 1s 1 1s 2 1s 2 2s 1 1s 2 2s 2 1s 2 2s 2 2p 1 1s 2 2s 2 2p 2 1s 2 2s 2 2p 3 1s 2 2s 2 2p 4 1s 2 2s 2 2p 5 1s 2 2s 2 2p 6 1s 2 2s 2 2p 6 3s 1 1s 2 2s 2 2p 6 3s 2 1s 2 2s 2 2p 6 3s 2 3p 1 1s 2 2s 2 2p 6 3s 2 3p 2 1s 2 2s 2 2p 6 3s 2 3p 3 1s 2 2s 2 2p 6 3s 2 3p 4 1s 2 2s 2 2p 6 3s 2 3p 5 1s 2 2s 2 2p 6 3s 2 3p 6 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 1 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 3 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 5 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 5 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 6 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 7 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 8 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 10 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn ELECTRONIC CONFIGURATIONS OF ELEMENTS 1-30

46. ELECTRONIC CONFIGURATION OF IONS Positive ions (cations) are formed by removing electrons from atoms Negative ions (anions) are formed by adding electrons to atoms Electrons are removed first from the highest occupied orbitals (EXC. transition metals) SODIUMNa1s 2 2s 2 2p 6 3s 1 1 electron removed from the 3s orbital Na + 1s 2 2s 2 2p 6 CHLORINECl1s 2 2s 2 2p 6 3s 2 3p 5 1 electron added to the 3p orbital Cl¯1s 2 2s 2 2p 6 3s 2 3p 6

47. ELECTRONIC CONFIGURATION OF IONS Positive ions (cations) are formed by removing electrons from atoms Negative ions (anions) are formed by adding electrons to atoms Electrons are removed first from the highest occupied orbitals (EXC. transition metals) SODIUMNa1s 2 2s 2 2p 6 3s 1 1 electron removed from the 3s orbital Na + 1s 2 2s 2 2p 6 CHLORINECl1s 2 2s 2 2p 6 3s 2 3p 5 1 electron added to the 3p orbital Cl¯1s 2 2s 2 2p 6 3s 2 3p 6 FIRST ROW TRANSITION METALS Despite being of lower energy and being filled first, electrons in the 4s orbital are removed before any electrons in the 3d orbitals. TITANIUMTi1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2 Ti + 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 2 Ti 2+ 1s 2 2s 2 2p 6 3s 2 3p 6 3d 2 Ti 3+ 1s 2 2s 2 2p 6 3s 2 3p 6 3d 1 Ti 4+ 1s 2 2s 2 2p 6 3s 2 3p 6

48. How is electronic configuration related to the structure of the Periodic Table?

49. Key Definitions Atomic Orbital = a region in an atom that can hold up to 2 electrons with opposite spins Principal quantum number, n = a number representing the overall energy of each orbital (increases with distance from the nucleus) A Shell or Energy Level = a group of atomic orbitals with the same quantum number, n. Electronic Configuration = the arrangement of electrons in an atom

50. Principal quantum number electron Atomic orbital Sub-shells (for the n=2 shell) The n=2 Shell Put arrows on to these labels

51. Principal quantum number electron Atomic orbital Sub-shells (for the n=2 shell) The n=2 Shell

52. AS Chemistry Unit F321 Module 1.2.1 Electron Structure Electron Structure Definitions & Examples Orbital Shell Principal Quantum Number Sub-shell Electron Configuration

53. AS Chemistry Unit F321 Module 1.2.1 Electron Structure Ionisation Energy First Ionisation Energy Successive Ionisation Energies Afffected by: Definition, Examples What they can be used to prove, graphs to show them, explanations:

54. What is wrong with this logo?

55. Unit F321 Module 1.2.1 Electron Structure