Bonding Flashcards
A
I
Describe the bonding in metals.
Lattice of metal / +ve ions/ cations / atoms (1)
(Surrounded by) delocalised electrons (1)
Explain how metals conduct electricity.
(d)
(Delocalised) electrons (1)
Move / flow in a given direction (idea of moving non-randomly)
A
A
Suggest why silicon dioxide does not conduct electricity when molten.
No delocalised electrons
Deduce the empirical formula of graphane
CH
Suggest why graphene is an excellent conductor of electricity.
Delocalised electrons / free electrons
Able to move / flow (through the crystal)
Titanium can be hammered into objects with different shapes that have similar strengths.
Suggest why these objects with different shapes have similar strengths.
bonding re-formed / same (metallic) bonding / retains same (crystal) structure / same bond strength / same attraction between protons and delocalised electrons as before being hammered
Suggest why the melting point of sodium iodide is lower than the melting point of sodium bromide
Iodide bigger ion so less attraction to sodium ion
(b) Describe the structure of and bonding graphite and explain why the mp of it is very high
Layers of carbon atoms
Connected by covalent bonds within each layer
VDW between layers
Many strong covalent bonds need to be broken
Explain how the ions are held together in solid sodium metal.
Attraction between positive ions and delocalised electrons
Explain how the ions are held together in solid sodium chloride.
Electrostatic attractions/forces between opp charged ions
(c) Compare the electrical conductivity of solid sodium metal with that of solid sodium chloride.
Explain your answer.
Describe the bonding in a crystal of iodine.
covalent between atoms (1)
Van der Waals’ between molecules
Name the crystal type which describes an iodine crystal.
Molecular
Explain why heat energy is required to melt an iodine crystal.
Bonds (or forces) between molecules must be broken or loosened
The heat energy needed to vaporise one mole of sodium chloride (171 kJ mol-1) is much greater than the heat energy required to melt one mole of sodium chloride
Explain why this is so.
All bonds must be broken (1)
Why is graphite soft?
Planes (1)
weak (bonds) forces between planes (1)
State the block in the Periodic Table in which sulphur is placed and explain your answer.
Block: p (1)
Explanation: Highest energy or outer orbital is (3) p
By reference to all the atoms involved explain, in terms of electrons, how Na2S is formed from its atoms.
Clear indication of electron transfer from Na to S (1)
1 e- from each (of 2) Na atoms
Draw a diagram, including all the outer electrons, to represent the bonding present in CS2
Deduce the name or formula of a compound that has the same number of atoms, the same
number of electrons and the same shape as the AICI4- ion.
SiCl4
Identify one molecule with the same number of atoms, the same number of electrons and the same shape as the H3O+ ion.
NH3
Covalent
Shared pair of electrons
Suggest one economic problem for the car user caused by incomplete combustion of ethanol in the car engine
More fuel needed (which costs more)/Wastes fuel/
less fuel burnt (so need more to buy more/engine gets sooty so need to pay for engine to be cleaned/Have to fit catalytic converter;
(d)
Propane is also used as a fuel, although sometimes it can be contaminated with sulfur-containing impurities. When this propane burns, these impurities form sulfur dioxide.
State how the sulfur dioxide can be removed from the waste gases produced when this propane is burned on a large scale in industry. Suggest a reason why the method you have stated may not be 100% efficient.
(i) (React) with CaO/ calcium oxide/quicklime/lime;
All the sulfur dioxide may not react with the CaO or CaCO,/ may not have time to react/ incomplete reaction;
Although propane has a boiling point of -42 °C, it is usually supplied as a liquid for use in camping stoves. Suggest why it is supplied as a liquid.
Occupies a (much) smaller volume;
boiling point of AsH3 is -62.5 °C and the boiling point of NH3 is -33.0 °C
Suggest why the boiling point of AsH is lower than that of NH
(t)
(Only) weak Van der Waals forces between molecules /AsH, has weaker IMF /ammonia has hydrogen bonding/ more energy needed to break IMF’s in ammonia/ Van der Waals weaker than H bonds;
Explain how the electron pair repulsion theory can be used to deduce the shape of, and the bond angle in, PF3
Perfume is a mixture of fragrant compounds dissolved in a volatile solvent.
When applied to the skin the solvent evaporates, causing the skin to cool for a short time.
After a while, the fragrance may be detected some distance away. Explain these observations
- Solvent has low bp or weak intermolecular forces or evaporates quickly
- needs energy to evaporate
- energy taken from the skin
- fragrance or perfume slowly spreads
- by diffusion/ random movement
