1. Chemsheets AS006 (Electron arrangement)
17/11/2018
PERIODICITY
© AS July-2015

2. The orbitals that the highest energy electrons are in
s block
p block
d block
The orbitals that the highest energy electrons are in
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3. Calcium 20 e- 1s2 2s2 2p6 3s2 3p6 4s2 s block
p block
d block
The orbitals that the highest energy electrons are in
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4. Iron e s2 2s2 2p6 3s2 3p6 4s2 3d d block Fe
s block
p block
d block
The orbitals that the highest energy electrons are in
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5. Chlorine e s2 2s2 2p p block Cl
s block
p block
d block
The orbitals that the highest energy electrons are in
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6. Helium 2 e- 1s s block He
s block
p block
d block
The orbitals that the highest energy electrons are in
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7. ATOMIC RADIUS
From:

8. ATOMIC RADIUS
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9. ATOMIC RADIUS Across a period: outer electrons are in same shell
more protons in nucleus
same amount of shielding
so stronger attraction between nucleus and outer shell electrons
so outer shell electrons pulled closer to nucleus Na Mg Al Si P S Cl
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10. 1st IONISATION ENERGY
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11. 1st IONISATION ENERGY General trend across period more protons
atoms get smaller
therefore stronger attraction from nucleus to electron in outer shell
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12. 1st IONISATION ENERGY Group 2 → 3
electron lost from: Group 3 = p orbital Group 2 = s orbital
p orbital is higher energy than s orbital, so easier to lose electron.
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13. 1st IONISATION ENERGY Group 5 → 6
Group 6 element loses electron from orbital with 2 electrons (p4 ).
Group 5 element loses electron from orbital with 1 electron (p3 ).
Extra electron-electron repulsions make it easier to lose electron from p4 than p3.
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14. ELECTRONEGATIVITY H
2.1 He Li
1.0 Be
1.5 B
2.0 C
2.5 N
3.0 O
3.5 F
4.0 Ne Na
0.9 Mg
1.2 Al Si
1.8 P S Cl Ar K
0.8 Ca Sc
1.3 Ti V
1.6 Cr Mn Fe Co Ni Cu
1.9 Zn Ga Ge As Se
2.4 Br
2.8 Kr Rb Sr Y Zr
1.4 Nb Mo Tc Ru
2.2 Rh Pd Ag Cd
1.7 In Sn Sb Te I Xe Cs
0.7 Ba La
1.1 Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Power of an atom to attract the 2 electrons in a covalent bond

15. ELECTRONEGATIVITY
Power of an atom to attract the 2 electrons in a covalent bond
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16. ELECTRONEGATIVITY Across a period: more protons in nucleus
Power of an atom to attract the 2 electrons in a covalent bond
Across a period:
more protons in nucleus
smaller atomic radius
so stronger attraction between nucleus and 2 electrons in covalent bond
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17. MELTING & BOILING POINTS
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18. MELTING & BOILING POINTS
Na metallic
Mg metallic
Al metallic
Si giant covalent
P4 simple molecular
S8 simple molecular
Cl2 simple molecular
Ar monatomic
Strong attraction between metal ions and delocalised electrons
Al > Mg > Na as
higher charge
more delocalised electrons
smaller ions
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19. Sodium (Na) Mpt 98ºC Magnesium (Mg) Mpt 650ºC+ e- + + + e- e- e- e- e- 2+ e- 2+ 2+ e- 2+ e- e- e- e- e- e- e- + + + e- 2+ e- 2+ e- e- 2+ e- e- e- e- e- 2+ 2+ 2+ e- 2+ + + e- + + e- e- e- e- e- e- e- 2+ 2+ 2+ e- e- + + +
Sodium (Na)
Mpt 98ºC
Magnesium (Mg)
Mpt 650ºC

20. MELTING & BOILING POINTS
Na metallic
Mg metallic
Al metallic
Si giant covalent
P4 simple molecular
S8 simple molecular
Cl2 simple molecular
Ar monatomic
Strong attraction between metal ions and delocalised electrons
Al > Mg > Na as
higher charge
more delocalised electrons
smaller ions
Have to break many strong covalent bonds
Weak van der Waals’ forces between molecules
S8 > P4 > Cl2 (bigger molecules, more electrons, more vdW)
Very weak van der Waals’ forces between atoms
© AS July-2015