Metallic bonding, ionic crystals, simple molecular crystals and giant molecular crystals (diamond and graphite), and how structure explains melting point, solubility and conductivity.
5 narrated scenes. Press play, listen and read along — the points appear as they are explained. Use ‹ Prev / Next › or the scene bar to jump to any scene.
Diamond is the hardest natural substance and graphite is soft enough to write with, yet both are pure carbon. The difference is how the atoms are joined.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Compare diamond, graphite and a metal. Notice how the bonding explains each property.
Copy these into your notebook in your own words — that is how they stick.
Attraction between positive ions and delocalised electrons.
Conduct (mobile electrons), malleable, ductile, high melting points.
High melting point; conducts when molten/dissolved; soluble in water.
Four bonds per C; very hard; non-conductor.
Three bonds per C; layers; soft; conducts.
Different structures of the same element.
Weak forces between molecules; low melting point; non-conductor.
Melting point, solubility, conductivity.
3 quick games on this lesson. Earn XP and badges as you play — your best score for each game is saved. Games are for practice and do not change your exam readiness. More games in the Chemistry Arcade.
8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better. Work each item on paper first.
Write full answers, then reveal the mark scheme and tick the points you earned (14 marks in total). Show all your working — method marks count. Your answers are saved on this device.
Question 1 [14 marks]
The table below gives properties of substances P, Q and R. P: melting point 801 °C; conducts only when molten or dissolved. Q: melting point 114 °C; does not conduct; soluble in organic solvents. R: melting point 3 500 °C; very hard; does not conduct.
(a) (a) Identify the type of structure of P, Q and R. [3]
(b) (b) Explain why P conducts electricity when molten but not when solid. [2]
(c) (c) Explain why Q has a low melting point. [2]
(d) (d) Explain why R is very hard. [2]
(e) (e) Explain why graphite, unlike diamond, conducts electricity and is soft. [3]
(f) (f) Explain why metals can be hammered into shape. [2]
Find these in your own past-paper booklets for extra timed practice. Items above are written in the style of these papers; any adapted from a specific question say so.