Chem Unit 1 (Periodic Table)

Question 1

Electrons in the same orbital have opposite..?

Answer 1

Spin

Question 2

Hund’s rule is?

Answer 2

Electrons will try and arrange themselves as far as possible from each other so will remain unpaired as much as they can.

Question 3

Lower energy levels are filled?

Answer 3

first

Question 4

An orbital can’t hold more than two

Answer 4

electrons

Question 5

Order goes, 1s2,

Answer 5

2s2, 2p6, 3s2, 3p6, 4s2, 4s6

Question 6

For ‘d’ block elements?

Answer 6

After 3d3, 4s2 empties first (PUT 2 ELECTRONS IN 4s (as it fills first) then TAKE ONE OUT (emties first) TO MAKE 3d5) THEN ONCE REFILL 4s I(2 electons again) AND CONTINUE FILLING 3D TO MAKE 3d6 ect

Question 7

Number of electrons and orbitals for s, p, d, f

Answer 7

s) electrons = 2/ orbitals = 1
p) electrons = 6 / orbitals = 3
d) electrons = 10 / orbitals = 5
f) electrons = 14 / orbitals = 7

Question 8

Number of electrons and orbitals for Principle energy level

Answer 8

1) 2 electrons / orbitals = 1
2) 8 electrons / orbitals = 4
3) 18 electrons / orbitals = 9
4) 32 electrons / orbitals = 16

Question 9

• ions you.. ?

Answer 9

add electrons

Question 10

+ ions you…?

Answer 10

minus electrons

Question 11

Half- full or full d shells are more…

Answer 11

stable

Question 12

Anomilies to electron stability

Answer 12

Cu + should be more stable than Cu 2+ because Cu+ has a half full d shell but Cu 2+ is.
Cr

Question 13

1st Ionisation energies

Answer 13

energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions
M (g) > M + (G) + e-

Question 14

Second ionisaton energy

Answer 14

energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 2+ ions
M (g) > M 2+ (g) + e-

Question 15

First ionisation energies down group 2?

Answer 15

• Each added electron is in a higher shell, further from the nucleus.
• Therefore there is increased shielding from inner electrons
• These together overrides the slightly increased nuclear charge
• Causes a decrease from Be-Ba

Question 16

Which ionisation energy is bigger?

Answer 16

The first ionisation energy is smallest as you are removing the electrons from a neutral atom whereas the second ionisation energy is removing it from a mole of ions with a positive charge
Going to have stronger attraction to nucleus so harder to remove
Ionisation energy increases as numbers go up

Question 17

Al3+ or Na+: Which is harder to remove?

Answer 17

size of the ion: Al3+ is smaller so the electrons are closer to the nucleus (stronger attraction)
Al3+ has a higher charge so stronger electrostatic attration

Question 18

Atomic radius down group 2?

Answer 18

• Added electrons join a new sub-shell, further from the nucleus so the atomic radius increases
• Therefore there is increased shielding from inner electrons.
• These override the slightly increased nucleur charge, bringing them in, decreasing it

Question 19

Atomic radius across period 3?

Answer 19

The electrons are added tot he same sub-shell

• Therefore this is no increased shielding from inner electrons.
• The significant increase in nuclear charge pulling it closer, overrides and decreases the atomic radius

Question 20

First ionisation energies across period 3 from Na>Ar

Answer 20

General increase from Na>Ar because of increased nucleur charge that overrides effect of increased shielding as electrons are added to same sub-shell, pulls the electrons closer to nucleus
Exceptions: Mg>Al
Al does have one more proton so an increased charge but in Al the electron is being removed from a 3p orbital rather than a 3s orbital like in Magnesium, - 3p is higher so takes less energy to remove (overrides the effect of the bigger nuclear charge so the ionisation energy decreases.
P>S
S does have one more electron but in sulfur its being removed from the 3p orbital that is FULL so the electrons are paired (strong repulsion)
Therefore its easier to remove the 4th electron compared to it being an unpaired electron.

Question 21

First ionisation energy from one period to the next..?

Answer 21

It decreases because there is increased nuclear charge because of the increased protons however, first elements of each period are added to a new main/sub-shell therefore increased shielding from inner electrons which overrides the increased nucleur charge.

Question 22

Melting points across peroid 3?

Answer 22

Na>Ar
Na>Mg>Al
All metallic bonding so strong electrostatic attraction between positively charged ions and negative electrons.
Increasing charge means more protons so more strongly attract electrons (more delocalised electrons) so increases from Na>Al,
Charge density also increases because the ionic radius decreases so the nucleus pulls in/more strongly attracts the electrons which takes more energy to overcome.
REMEMBER: small increase from Mg>Al
Al>Si
Large increase because silicon is a macromolecular giant structure with strong ovalent bonds and some of these have to eb broken for it to melt so requires a lot of energy](Si has the highest boiling point)
Si>P
Decreases a lot (down to same level to Na)
Because phosphorus is a simple molecular so only has weak Van der Waals forces of attraction between molecules
P4>S8
small increase (both are simple molecular but sulfur exists as S8 so is a bigger molecule than P4 so more Van der Waals (more energy needed)
S8>Cl2
larger decrease (both are simple molecular) but Cl2 is a smaller molecule so less Van der Waals- bigger difference than P4>S8 as S8>Cl2 is a bigger difference (Line goes past 0)
Cl2>Ar
Further decrease because Ar exists as simply atoms so doesn’t even need to bond to get a full outer shell so takes little energy to break bonds

Question 23

Boiling points across peroid 3?

Answer 23

Na>Ar
For a liquid to boil, all the bonds must be broken )not just some like in a liquid) so the amount of energy required is greater for all.
Na>Mg>Al
Increased metallic bonding (stronger attraction), higher charge density, smaller ionic radius means it takes more energy to break all bonds.
REMEMBER: small increase from Na>Mg instead of Mg>Al
Al>Si
Small decrease because most of the covalent bonds in silicon have been broken (some are still unbroken) BUT these are not quite as strong as the metallic bonds in liquid aluminium so he amount of energy needed decreases a bit.
P4>S8>Cl2>Ar
Same rules as melting points
- All simple molecular but the bigger the molecule the more Van der Waals and the more energy required to break bonds
- Ar is just atoms so requires smallest amount.