Inorganic: period 3 Flashcards
Explain the trend in atomic radius in period three
Increases across, more protons, so higher nuclear charge, so stronger nuclear attraction between outer electron and nucleus.
Explain the trend in melting point for Na, Mg and Al
Increases, due to giant metal structure. PMI-SDE greater attraction between positive ions and delocalised electrons so more energy to overcome.
Explain the melting point in silicon
Giant covalent structure which requires a lot of energy to overcome bonds
Explain the trend in melting point for P4,S8, and Cl2.
Decreases, simple covalent molecules so little energy needed to overcome VDW forces. S8 is higher because it’s a bigger molecule/more electrons so stronger VDW
Explain the trend in ionisation energy for period three
Increases, bigger nuclear charge so stronger nuclear attraction so harder to lose outer electron
Why does the ionisation energy drop in group 3 (Al)
Als outer electron is in the p orbital while Mgs is in the s orbital. P is a higher energy level so needs less energy to remove it
Why does the ionisation energy drop in group 6 (S)
S has two of its electrons in a pair in the same p orbital so they repel meaning less energy is needed to remove them
Explain why the melting point of silicon is very high
Giant covalent, which require lots of energy to overcome covalent bonds
Why does the atomic radius decrease across period three?
More protons, so greater nuclear charge so greater nuclear attraction between outer electron and nucleus
Which has a lower ionisation energy, magnesium or aluminium?
Aluminium as it’s outer electron is in the p orbital which is a higher energy level so requires less energy to lose outer electron
Why is the melting point higher in S than in P
S has more electrons and is a bigger molecule so has stronger VDW forces which require more energy to overcome
Which is smaller, Na+ or Mg2+ ?
Mg2+ as it has more protons so a smaller atomic radius, with the same shielding/ number of electrons
