Charge on the ion formed by a group 16 element?
Answer: 2−
Formula of calcium phosphate?
Answer: Ca₃(PO₄)₂
Ionic compounds conduct electricity only when…?
Answer: Molten or aqueous
IB Chemistry · Structure 2
IB Chemistry Structure 2: Models of bonding and structure
5 ready-made review sets for this topic, by subtopic and marked SL or HL, 70 questions in all, to play as a class game on the projector. Free to host, and students join with a code.
A question from the sets
Charge on the ion formed by a group 16 element?
- 2+
- 6+
- 6−
- 2−Right answer
What Structure 2 covers
Structure 2 explains properties from bonding. S2.1 is the ionic model: how ions form, the formulas and names of ionic compounds, polyatomic ions included, and the lattice that gives them high melting points. S2.2 is the covalent model: Lewis formulas and coordination bonds, VSEPR shapes and bond angles, bond and molecular polarity, intermolecular forces from London dispersion forces to hydrogen bonding, covalent network structures such as diamond and graphite, and chromatography. At higher level it adds formal charge, resonance and benzene, sigma and pi bonds, hybridisation and shapes with five and six electron domains. S2.3 is the metallic model, and S2.4 brings the three together: the bonding triangle, alloys and polymers.
Where students slip
- A molecule can have polar bonds and still be non-polar. In CO₂ the two C=O bond dipoles point in opposite directions and cancel; in H₂O the molecule is bent, so they don't.
- Melting or boiling a simple molecular substance overcomes the intermolecular forces between the molecules. The covalent bonds inside them don't break.
- Lone pairs repel more than bonding pairs, which is why the bond angle is 107° in NH₃ and 104.5° in H₂O, not the 109.5° of a regular tetrahedron.
The sets
Play this set opens the set in splycr, where you can read every question and host it for your class straight away. Hosting needs no account, and students join with the code on the board. A free account lets you copy a set and edit it.
The questions were written for the splycr library by Biology by Bradford. Each one plays as multiple choice, and the three wrong options were written for that question.
Sets marked SL suit every IB Chemistry student, because higher level students study the standard level content too. Sets marked HL cover the additional higher level material: ten subtopics have an HL set after their SL one, and R1.4 Entropy and spontaneity, which is for higher level only, has an HL set of its own.
S2.1 The ionic model
S2.2 The covalent model
Molecular geometry of NH₃?
Answer: Trigonal pyramidal
Molecule with polar bonds but no overall dipole?
Answer: CO₂
Only intermolecular force between non-polar molecules such as I₂?
Answer: London dispersion forces
Molecular geometry of XeF₄?
Answer: Square planar
Numbers of sigma and pi bonds in ethyne, H–C≡C–H?
Answer: 3 σ, 2 π
Bond order of each C–O bond in CO₃²⁻?
Answer: 1.33
S2.3 The metallic model
Metals conduct electricity because they contain…?
Answer: Delocalised electrons
Metallic bonding is stronger for cations with higher charge and smaller…?
Answer: Ionic radius
Order of increasing melting point for Al, Na and Mg?
Answer: Na, Mg, Al
S2.4 From models to materials
Bonding type for a large ΔEN, such as in CsF?
Answer: Ionic
Alloys are harder than pure metals because different-sized atoms…?
Answer: Prevent layers sliding
Monomer used to make PVC?
Answer: Chloroethene
Game modes that suit this topic
Every set plays in all eight modes. These two fit this topic best.
Boss Battle
Structure 2 is full of answers that sit side by side: trigonal planar and trigonal pyramidal, ductile and malleable, sigma and pi. A wrong answer heals the boss, so the class gains nothing by guessing a shape.
Throne
Ion formulas and molecular shapes reward the student who really knows them. One student holds the throne and the class answers to take it, and a wrong answer from the champion costs double.