stuff to note

Question 1

first ionisation energy

trend and exceptions

Answer 1

trend: increases across period, decreases down period

exceptions:

1. grp 13 has lower first IE than grp 2
   - valence electron to be removed from grp 13 is found in p subshell which is higher energy level and further away from nucleus than valence electron to be removed from grp 2 which is in s subshell
   - requires less energy to remove
2. grp 16 has lower first IE than grp 15
   - grp 16 element experiences electron-electron repulsion between its pair of valence electrons in one of its p orbitals
   - less energy required to remove valence electron

Question 2

deviations from Aufbau principle in grp 6 and 11

Answer 2

chromium (and molybdenum)
3d5 4s1 is more stable than 3d4 4s2

copper
3d10 4s1 is more stable than 3d9 4s2

these configurations are preferred bc they result in more symmetrical 3d electron cloud that shields nucleus more effectively

Question 3

down a group (general)

Answer 3

• number of protons and electrons increase so nuclear charge increases
• number of electron shells increase so shielding effect increases
• ENC remains almost the same (***rmb)
• valence shell lies further from nucleus so attraction decreases

Question 4

across a period (general)

Answer 4

• number of protons and electrons increase so nuclear charge increases
• number of e shells stays the same so shielding effect remains about the same
• ENC increases
• valence electrons more attracted to nucleus, so are closer to nucleus