C3 - Structure and Bonding Flashcards
What happens in ionic bonding?
-transfer of e- from metal to non-metal atom in a reaction
-forms strong non-directional electrostatic force of attraction between the oppositely charged ions
What is an ionic compound?
-giant lattice structure of oppositely charged ions
-held together by strong ionic bonds
the spec says you should be familiar with the structure displayed
Give some properties of ionic compounds:
-hard and brittle
-high M/BP (strong bonds)
-conducts when molten/dissolved (ions can move)
They are hard/brittle because it is difficult to make one layer of ions shift relative to another layer, due to the ions being oppositely charged
Why would a metal chloride usually be a solid at room temperature?
-metal chlorides are usually ionic
-they have strong electrostatic forces of attraction between their oppositely charged ions
-which require a lot of energy to overcome
-so they are solid at room temperature because of their high melting points
Don’t just say strong ionic bonds for these questions as it isn’t enough, they want you to explain why the melting point is high
Define covalent bonding:
-shared electron(s) between 2 non-metal atoms
-forms a strong directional ES force of attraction between the shared electron(s) and the 2 nuclei
What is a molecule?
a fixed number of atoms covalently bonded together with weak IM forces between molecules
What is the bonding diagram for nitrogen gas?
triple covalent bond, and a pair on either side
What is the bonding diagram for hydrogen chloride?
single covalent bond, with chlorine having the other 6 electrons paired on the opposite side
What governs the bulk properties of a simple molecular substance?
the weak intermolecular forces between the individual molecules
Give 2 properties of simple molecular substances:
-low M/BP due to weaker intermolecular forces
-not conductors (made of uncharged molecules)
Give 2 properties of polymers:
-higher M/BP than simple molecules (larger molecules, ^IM forces)
-usually solid at room temp.
Give 5 properties of giant covalent structures:
-high M/BP (need to break ALL strong cov. bonds)
-insoluble in water
-hard + brittle
-insulators
Graphite is a slight exception as it is soft (due to the layers) and a conductor
Define metallic bonding:
-strong ES non-directional force of attraction
-between the metal ions and the delocalised electrons that are free to move about the lattice structure
metals which lose more outer electrons will have more delocalised electrons, and will form a stronger metallic bond
Give 3 properties of pure metals:
-high M/BP (strong metallic bonds)
-soft (malleable and ductile)
-conductors of heat/electricity (due to delocalised electrons)
electrons can transfer both heat and electricity
What are alloys, and how are they different from pure metals?
-a mixture that is harder than pure metals
-different sized atoms distorts regular layers in the pure metal
-can no longer slide over each other as easily
Explain the difference between hardness and strength:
-hardness is the resistance to being scratched
-strength is the ability to withstand a force without becoming deformed
-if something is hard, it is brittle (has a low resistance to impact)
What does particle theory describe?
the different states of matter, and their differences in density
What are the limitations of particle theory?
it assumes all particles are solid, inelastic, homogenous spheres with no forces between them
homogenous spheres means particles that are all the same
Give some limitations of using dot and cross diagrams to represent molecules:
-doesn’t show its shape
-only 2 dimensional
What is an allotrope?
different forms of the same element in the same physical state
Describe the structure of diamond:
each carbon atom forms 4 strong covalent bonds with other carbon atoms in a giant covalent structure (tetrahedral)
diamond is an allotrope of carbon
Describe the structure of graphite:
-each carbon atom forms 3 strong covalent bonds with other carbon atoms forming a giant covalent structure
-makes layers of hexagonal rings (graphene) with weak IM forces between the layers
-1 electron from each carbon atom is delocalised, and exists between the graphene layers
graphite is an allotrope of carbon
Describe the differences in properties between graphite and graphene:
(graphite)
-soft, malleable, good conductor
(graphene)
-very strong, good conductor
Explain why graphite can conduct electricity:
-each carbon forms a strong covalent bonds to 3 other carbon atoms in a giant covalent structure
-one electron per carbon atom is delocalised
-they can carry a charge through the graphite
Don’t say that it can carry current/electricity, its too vague and isn’t accepted
Where is graphene used?
-composite materials
-electronics
-lubricants
What are fullerenes?
molecules of carbon atoms that are hollow spheres/tubes
eg C60, Buckminsterfullerene
Why are fullerenes good for drug delivery around the body?
they are hollow so they can fit other drug molecules inside them
What are nanotubes and their properties? How are they used in industry?
-cylindrical fullerenes (hollow tubes of carbon atoms)
-very high length : diameter ratio, and high tensile strength
-useful for nanotechnology, electronics, and materials
What are nanoparticles, and how do they compare to other types of particles?
-particles of the size 1-100nm diameter
-smaller than PM2.5 (100-2500nm) and coarse particles (dust) that are PM10 (2500nm-10,000nm)
What property of nanoparticles makes it more useful than any other material?
-high SA:V, so it is far more reactive
-need less than its bulk material to have the same desired effect, so it is more sustainable in industry (less material used)
Give 5 uses of nanoparticles:
-catalysts
-lubricants
-electronics
-cosmetics (sun cream and deodorant)
-medicine (drug delivery, cancer treatment, antimicrobial wound dressings)
cancer treatments often use gold nanoparticles that are heated using a laser, which vibrate a lot and damage the proteins in the tumour
What are 3 risks that should be considered when using nanoparticles?
-explosive/highly reactive (high SA:V)
-can cause lung damage if inhaled
-atmospheric pollution + damages aquatic life
How can you tell if an equation is balanced?
-it has the same number of atoms on both sides
-of the SAME TYPE
this lost you a mark in some ppq’s
If you are stuck on a physical properties question, what is a always a good backup property to add?
if it is usually a solid/liquid/gas at room temperature, as you can just add it onto the statement about its melting/boiling point
Why can a solution of sodium chloride conduct electricity?
-there are charged sodium and chlorine ions in the water
-which can move and carry a charge
Explain why chlorine is more reactive than iodine:
-chlorine’s outer electrons are closer to the nucleus
-its nucleus exerts a stronger ES force of attraction on its outer electrons
-it can gain an electron more easily to complete its outer shell
Why is hydrogen chloride a gas at room temperature?
-hydrogen chloride is made of small molecules
-it has weak IM forces
-requires very little energy to overcome
Don’t mention breaking bonds, only overcoming the forces
