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A LEVEL ELECTRON ARRANGEMENTS

Learn about how electrons fill energy levels and the different sub-levels. Explore the sub-shell notation and the filling order rules for orbitals. Gain a deeper understanding of electron configurations and their placement in atomic orbitals.

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A LEVEL ELECTRON ARRANGEMENTS

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  1. A LEVEL ELECTRON ARRANGEMENTS OBJECTIVES:To describe how electrons fill energy levels, including the s, p, d and f sub-levelsTo explain how chromium and copper are ‘different’ SUMMARY SO FAR…Write a 3 sentence summary of electrons as you know them at present KEY WORDS:ENERGY LEVEL ORBITAL SUB-LEVEL SPIN

  2. A LEVEL ELECTRON ARRANGEMENTS Shells • Each shell you know from GCSE is split into sub-shells, each with slightly different energies • These sub-shells are called s, p,d and f sub-shells • Each subshell has orbitals. • Each orbital can hold 2 electrons • Copy the table from page 18 and describe in one sentence what it shows you

  3. A LEVEL ELECTRON ARRANGEMENTS Sub-Shell Notation • There is a way of writing electron configuration you HAVE TO KNOW!!! • Neon has 10 electrons, so write it using sub-shell notation: • Now try this with Lithium, then Nitrogen and oxygen • And finally, Calcium…

  4. A LEVEL ELECTRON ARRANGEMENTS ENERGY LEVELS • Electrons have fixed energies, they move around the nucleus in regions called shells or energy levels • Different shells have differing amounts of energy. Level 1 contains electrons closest to the nucleus. These have the lowest energy • Not all the electrons in a shell have exactly the same amount of energy. • Shells are divided into sub-shells that have slightly different energies • Sub shells have orbitals which can each hold up to 2 electrons

  5. 4f 4d 4 4p 3d 3p 3 3s 2p 2 2s 1 1s A LEVEL ELECTRON ARRANGEMENTS FILLING ORBITALS PRINCIPAL ENERGY LEVELS SUB LEVELS 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. 4s

  6. 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 7s 7p A LEVEL ELECTRON ARRANGEMENTS HOW TO REMEMBER THE FILLING ORDER RULES FOR FILLING ORBITALS: • Fill up lowest energy sub levels first (Aufbau Principle) • Fill orbitals singly at first before doubling (Hund’s Rule) • Remember that 4s is filled before 3d!

  7. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s A LEVEL ELECTRON ARRANGEMENTS PUTTING ELECTRONS INTO ATOMIC ORBITALS Orbitals within a sub level can be shown as boxesElectrons have a property called ‘spin’ (although electrons are not actually spinning)2 electrons in the same orbital must have opposite spinsWe represent electrons using half arrows either pointing up or down 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS

  8. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s A LEVEL ELECTRON ARRANGEMENTS THE AUFBAU PRINCIPLE: This states that… “ELECTRONS ENTER THE LOWEST AVAILABLE ENERGY LEVEL” 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS The following sequence will show the ‘building up’ of the electronic structures of the first 36 elements in the periodic table.

  9. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS HYDROGEN 1s1 Hydrogen atoms have one electron. This goes into a vacant orbital in the lowest available energy level. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS ‘Aufbau’ Principle

  10. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS HELIUM 1s2 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. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS ‘Aufbau’ Principle

  11. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS LITHIUM 1s2 2s1 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. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS ‘Aufbau’ Principle

  12. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS BERYLLIUM 1s2 2s2 Beryllium atoms have four electrons so the fourth electron pairs up in the 2s orbital. The 2s sub level is now full. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS ‘Aufbau’ Principle

  13. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS BORON 1s2 2s2 2p1 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. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS ‘Aufbau’ Principle

  14. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS CARBON 1s2 2s2 2p2 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. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS HUND’S RULE OF MAXIMUM MULTIPLICITY

  15. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS NITROGEN 1s2 2s2 2p3 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. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS HUND’S RULE OF MAXIMUM MULTIPLICITY

  16. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS OXYGEN 1s2 2s2 2p4 With all three orbitals half-filled, the eighth electron in an oxygen atom must now pair up with one of the electrons already there. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS ‘Aufbau’ Principle

  17. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS FLUORINE 1s2 2s2 2p5 The electrons continue to pair up with those in the half-filled orbitals. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS

  18. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS NEON 1s2 2s2 2p6 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. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS

  19. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s 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. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS ‘Aufbau’ Principle

  20. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS SODIUM - ARGON Na 1s2 2s2 2p6 3s1 Mg 1s2 2s2 2p6 3s2 Al 1s2 2s2 2p6 3s2 3p1 Si 1s2 2s2 2p6 3s2 3p2 P 1s2 2s2 2p6 3s2 3p3 S 1s2 2s2 2p6 3s2 3p4 Cl 1s2 2s2 2p6 3s2 3p5 Ar 1s2 2s2 2p6 3s2 3p6 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS Remember that the 3p configurations follow Hund’s Rule with the electrons remaining unpaired to give more stability.

  21. Period 3: Period 3: Period 3 Continued: SODIUM - ARGON POTASSIUM COBALT 1s2 2s2 2p6 3s2 3p6 4s1 1s2 2s2 2p6 3s2 3p6 4s2 3d7 Na 1s2 2s2 2p6 3s1 Mg 1s2 2s2 2p6 3s2 Al 1s2 2s2 2p6 3s2 3p1 Si 1s2 2s2 2p6 3s2 3p2 P 1s2 2s2 2p6 3s2 3p3 S 1s2 2s2 2p6 3s2 3p4 Cl 1s2 2s2 2p6 3s2 3p5 Ar 1s2 2s2 2p6 3s2 3p6 NICKEL CALCIUM 1s2 2s2 2p6 3s2 3p6 4s2 3d8 1s2 2s2 2p6 3s2 3p6 4s2 COPPER SCANDIUM 1s2 2s2 2p6 3s2 3p6 4s1 3d10 1s2 2s2 2p6 3s2 3p6 4s2 3d1 ZINC TITANIUM 1s2 2s2 2p6 3s2 3p6 4s2 3d10 1s2 2s2 2p6 3s2 3p6 4s2 3d2 VANADIUM 1s2 2s2 2p6 3s2 3p6 4s2 3d3 CHROMIUM 1s2 2s2 2p6 3s2 3p6 4s1 3d5 MANGANESE 1s2 2s2 2p6 3s2 3p6 4s2 3d5 IRON 1s2 2s2 2p6 3s2 3p6 4s2 3d6

  22. Transition Metals WALT: Be able to draw arrow boxes on energy level diagrams for Transition metals Know the two ‘Special’ cases

  23. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS CHROMIUM 1s2 2s2 2p6 3s2 3p6 4s1 3d5 One would expect the configuration of chromium atoms to end in 4s2 3d4. 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. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS HUND’S RULE OF MAXIMUM MULTIPLICITY

  24. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS COPPER 1s2 2s2 2p6 3s2 3p6 4s1 3d10 One would expect the configuration of chromium atoms to end in 4s2 3d9. To achieve a more stable arrangement of lower energy, one of the 4s electrons is promoted into the 3d. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS

  25. Period 4: Period 4 Continued: COBALT SCANDIUM 1s2 2s2 2p6 3s2 3p6 4s2 3d7 1s2 2s2 2p6 3s2 3p6 4s2 3d1 NICKEL TITANIUM 1s2 2s2 2p6 3s2 3p6 4s2 3d8 1s2 2s2 2p6 3s2 3p6 4s2 3d2 COPPER VANADIUM 1s2 2s2 2p6 3s2 3p6 4s1 3d10 1s2 2s2 2p6 3s2 3p6 4s2 3d3 CHROMIUM ZINC 1s2 2s2 2p6 3s2 3p6 4s1 3d5 1s2 2s2 2p6 3s2 3p6 4s2 3d10 MANGANESE 1s2 2s2 2p6 3s2 3p6 4s2 3d5 IRON 1s2 2s2 2p6 3s2 3p6 4s2 3d6

  26. Period 4: Period 4 Continued: POTASSIUM COBALT 1s2 2s2 2p6 3s2 3p6 4s1 1s2 2s2 2p6 3s2 3p6 4s2 3d7 NICKEL CALCIUM 1s2 2s2 2p6 3s2 3p6 4s2 3d8 1s2 2s2 2p6 3s2 3p6 4s2 COPPER SCANDIUM 1s2 2s2 2p6 3s2 3p6 4s1 3d10 1s2 2s2 2p6 3s2 3p6 4s2 3d1 ZINC TITANIUM 1s2 2s2 2p6 3s2 3p6 4s2 3d10 1s2 2s2 2p6 3s2 3p6 4s2 3d2 VANADIUM 1s2 2s2 2p6 3s2 3p6 4s2 3d3 CHROMIUM 1s2 2s2 2p6 3s2 3p6 4s1 3d5 MANGANESE 1s2 2s2 2p6 3s2 3p6 4s2 3d5 IRON 1s2 2s2 2p6 3s2 3p6 4s2 3d6

  27. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS POTASSIUM 1s2 2s2 2p6 3s2 3p6 4s1 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. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS ‘Aufbau’ Principle

  28. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS CALCIUM 1s2 2s2 2p6 3s2 3p6 4s2 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 -s1 electronic configuration are in Group I and all with an -s2 configuration are in Group II. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS ‘Aufbau’ Principle

  29. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS SCANDIUM 1s2 2s2 2p6 3s2 3p6 4s2 3d1 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. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS HUND’S RULE OF MAXIMUM MULTIPLICITY

  30. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS TITANIUM 1s2 2s2 2p6 3s2 3p6 4s2 3d2 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. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS HUND’S RULE OF MAXIMUM MULTIPLICITY

  31. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS VANADIUM 1s2 2s2 2p6 3s2 3p6 4s2 3d3 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. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS HUND’S RULE OF MAXIMUM MULTIPLICITY

  32. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS CHROMIUM 1s2 2s2 2p6 3s2 3p6 4s1 3d5 One would expect the configuration of chromium atoms to end in 4s2 3d4. 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. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS HUND’S RULE OF MAXIMUM MULTIPLICITY

  33. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS MANGANESE 1s2 2s2 2p6 3s2 3p6 4s2 3d5 The new electron goes into the 4s to restore its filled state. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS HUND’S RULE OF MAXIMUM MULTIPLICITY

  34. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS IRON 1s2 2s2 2p6 3s2 3p6 4s2 3d6 Orbitals are filled according to Hund’s Rule. They continue to pair up. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS HUND’S RULE OF MAXIMUM MULTIPLICITY

  35. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS COBALT 1s2 2s2 2p6 3s2 3p6 4s2 3d7 Orbitals are filled according to Hund’s Rule. They continue to pair up. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS HUND’S RULE OF MAXIMUM MULTIPLICITY

  36. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS NICKEL 1s2 2s2 2p6 3s2 3p6 4s2 3d8 Orbitals are filled according to Hund’s Rule. They continue to pair up. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS HUND’S RULE OF MAXIMUM MULTIPLICITY

  37. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS COPPER 1s2 2s2 2p6 3s2 3p6 4s1 3d10 One would expect the configuration of chromium atoms to end in 4s2 3d9. To achieve a more stable arrangement of lower energy, one of the 4s electrons is promoted into the 3d. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS

  38. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS ZINC 1s2 2s2 2p6 3s2 3p6 4s2 3d10 The electron goes into the 4s to restore its filled state and complete the 3d and 4s orbital filling. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS

  39. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s 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. 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS HUND’S RULE OF MAXIMUM MULTIPLICITY

  40. 4f 4d 4 3d 4p 3 3p 3s 2p 2 2s 1 1s THE ELECTRONIC CONFIGURATIONS OF THE FIRST 36 ELEMENTS GALLIUM - KRYPTON Prefix with… 1s2 2s2 2p6 3s2 3p6 4s2 3d10 Ga - 4p1 Ge - 4p2 As - 4p3 Se - 4p4 Br - 4p5 Kr - 4p6 4s INCREASING ENERGY / DISTANCE FROM NUCLEUS Remember that the 4p configurations follow Hund’s Rule with the electrons remaining unpaired to give more stability.

  41. 1.5 MORE ELECTRON ARRANGEMENTS SHORTHAND ELECTRONIC CONFIGURATIONS Rather than drawing box and arrow diagrams we can use a shorthand method that writes out the sublevels:E.g. Sodium (11 electrons) 1s2 2s2 2p6 3s1 Can simplify things further by using previous noble gas symbol. E.g. Calcium 1s2 2s2 2p6 3s2 3p6 4s2 becomes [Ar] 4s2 What about for ions?

  42. 1.5 MORE ELECTRON ARRANGEMENTS OVER TO YOU Draw spin diagrams for the first 36 elements [Remember be careful with chromium and copper!] Add in the full shorthand electronic configurations Come up to the front to mark your work when done EXTENSION: Summary Questions on page 16

  43. 1.5 MORE ELECTRON ARRANGEMENTS 1. Lithium 1s2 2s1 2. Neon 1s2 2s2 2p6 3. 1s2 2s2 2p3 Nitrogen 4. 1s2 2s2 2p6 3s2 3p1 Aluminium 5. Potassium 1s2 2s2 2p6 3s2 3p6 4s1 6. 1s2 2s2 2p6 3s2 3p6 3d5 4s1 Chromium

  44. 1.5 MORE ELECTRON ARRANGEMENTS CHAMPIONS LEAGUE FINAL Top scorer from each group now go head to head to be crowned Electron King/Queen First correct whiteboard placed in front of me wins Q:Write the shorthand for Copper 1s2 2s2 2p6 3s2 3p6 3d10 4s1

  45. 1.5 MORE ELECTRON ARRANGEMENTS SUMMARY SO FAR…Write a 3 sentence summary of electron arrangements as you now know them  how does it differ to your summary at the start??

  46. 1.5 MORE ELECTRON ARRANGEMENTS ENERGY LEVELS Each orbital in a sub-level can hold a maximum of 2 electronsThere is a single s-orbital, 3 p-orbitals of the same energy, 5 d-orbitals and 7 f-orbitals

  47. 1.5 MORE ELECTRON ARRANGEMENTS WHAT ARE ORBITALS? Electrons are no longer considered as particles but as a cloud of negative chargeAn orbital is a region in this space where we are 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...

  48. 1.5 MORE ELECTRON ARRANGEMENTS SHAPE OF ORBITALS ORBITAL SHAPE OCCURRENCE s spherical one in every principal level p dumb-bell three in levels from 2 up d various five in levels from 3 up f various seven in levels from 4 up

  49. 1.5 MORE ELECTRON ARRANGEMENTS SHAPE OF ORBITALS S orbital P orbitals

  50. 1.5 MORE ELECTRON ARRANGEMENTS SHAPE OF ORBITALS D orbitals

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