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GCSE9 Struct & Prop
AQA GCSE chapter 03 (part2 ) Bonding, structure and properties
| Question | Answer |
|---|---|
| Describe how particles are arranged in an ionic structure | Ions are arranged in 3dimensions; the ions create a LATTICE of ALTERNATE positive ions and negative ions |
| Describe THREE properties of ionic compounds | Conduct electricity when liquid; high meting point and dissolve in water |
| Explain why ionic compounds are able to conduct electricity when liquid but not as a solid | CHARGED particles (here ions) are able to MOVE in a liquid; but in a solid the charged particles can NOT move |
| Explain why ionic compounds have a high melting point | There are STRONG electrostatic BONDBETWEEN the ions that require a lot of ENERGY to break |
| How do you know that CO2 is a covalent compound? | Both C and O are non-metals |
| What is covalent bonding? | SHARING of PAIR of electrons (two keywords to remember!) |
| How to you draw a dot and cross diagram? | Overlap circles; in the middle place a dot and a cross; check the group number |
| What is special about the dot and cross diagram of CO2? | There are TWO dots and TWO crosses (ie TWO pairs of electrons) in each overlap |
| State 3 properties of simple covalent compounds | Low melting point; do not conduct electricity;do not dissolve |
| Describe how to draw the dot and cross diagram for CCl4 | Draw one circle for the Carbon atom; overlap FOUR circles (one for each chlorine atom) with the carbon; dot and cross in middle; add remaining 6 electrons on the Chlorine circles |
| Describe how to draw the dot and cross diagram for NH3 | Draw one circle for the Nitrogen Atom; overlap 3 circles (One for each Hydrogen) with the Nitrogen; dot and cross in the middle; add remaining two electrons on the nitrogen circle |
| Explain why simple covalent chemicals like Methane (CH4) have low melting point | There are weak BONDBETWEEN MOLECULES; very little ENERGY is required to separate the molecules |
| Explain why simple covalent compounds do not conduct electricity | There are no CHARGES (like electrons) able to MOVE (because they are shared/stuck in the middle) |
| Name the two forms of Carbon | Diamond and Graphite |
| State the difference in properties between Diamond and Graphite | Diamond is very hard; Graphite is very soft and comes in layers |
| describe the structure of Graphite | Each atom of Carbon is linked to 3 other Carbons; the Carbons form sheets/layers that are loosely bonded |
| Describe the structure of Diamond | Each Carbon atom is bonded to 4 other Carbon; the Carbons form a 3D network |
| Explain why Graphite conducts electricity | Each Carbon is linked to 3 other Carbons; so each Carbon has a spare electron; all the spares electrons are DELOCALISED (do not stay on one carbon; are shared with all the atoms); electrons can move BETWEEN LAYERS |
| Explain why Diamond does not conduct electricity | Each Carbon is linked to 4 other Carbon atoms; there is no spare electron; there are no charges able to move |
| Explain why graphite has a high melting point | Because there are MANY strong COVALENT bondbetween ATOMS to break and this requires a lot of energy to break; remember to clearly write WHICH PARTICLES |
| Explain why diamond is so hard | Because there are MANY strong COVALENT bondbetween ATOMS to break and this requires a lot of energy to break; remember to clearly write WHICH PARTICLES |
| Why is graphite soft? | Because there are weak BONDBETWEEN layers of ATOMS so little energy is required to break these bonds |
| Describe metallic structure | A lattice of FIXED positive ions surrounded by a SEA of DELOCALISED electrons |
| State 2 properties of metallic structure | Conduct electricity; High melting point |
| Explain why metallic structures conduct electricity | There are CHARGED particles (delocalised electrons) that are able to to MOVE |
| Explain why Iron has a high melting point | Because there are strong BONDBETWEEN positive IONS and delocalised ELECTRONS and this requires a lot of energy to break; remember to clearly write WHICH PARTICLES |
| Explain why metals are malleable | because when a metal is hit, a layer of ion slides over the other layers but the positive ions are still held together by delocalised electrons |
| Compare the structure of an alloy to the structure of a metal | In an alloy, there are BIGGER atoms than in the metal atoms; this means that the layers of atoms are distorted |
| Explain why an alloy is stronger than a pure metal | In an alloy, there are BIGGER atoms than in the metal atoms; this means that the layers of atoms are distorted; so when an alloy is hit the layers cannot slide past one other. |
| A chemical conduct electricity when molten but not as a solid: what type of structure? | Ionic structure |
| A chemical does not conduct electricity and has a low melting point. What type of structure? | Simple Covalent |
| A chemical does not conduct electricity and has a high melting point. What type of structure? | Giant Covalent |
| A chemical conducts electricity when liquid and solid and has a high melting point. What type of structure? | Metallic |
| What are the properties of nanotubes? | they are light, yet very strong and conduct electricity as well as heat |
| What are nanotubes used for? | making tennis rackets (strong but light) |
| (TRIPLE ONLY) What are nanoparticles used for? | Titanium oxide nanoparticles help break down the dirt on glass windows; they are also used in sunscreens; Silver nanoparticles inhibit the growth of microorganisms |
| (TRIPLE ONLY) What is the risk of nanoparticles? | they could damage lungs, get in our bloodstream and the effects in our blood are unknown |
| (TRIPLE ONLY) what is a nanometre | 0.000000001m or 10^-9m |
| (TRIPLE ONLY) how many nanometres in a micrometre? | LEARN: 1 micrometre is 10^-6m; so 1nanometre is 1000 times smaller than a micrometre |
| (TRIPLE ONLY) what happens to the surface area to volume ratio when the size of a cube is decreased by 10? | the surface area to volume ratio INCREASE by a factor of 10! This make nanoparticles much more reactive than normal sized particles |
| (TRIPLE ONLY) how many nanometres in a micrometre? | LEARN: 1 picometre is 10^-12m; so 1nanometre is 1000 times bigger than a picometre |
| Describe a fullerene | A sphere made of hexagons and pentagons |
| Describe possible uses for fullerenes in the future | Deliver drugs inside the body (the drug is inside the cage), catalysts (because of the very high surface to volume ratio) and lubricants |
| Describe graphene | A single sheet of carbon atoms forming inter-locking hexagons; it is just ONE ATOM THICK |
| Describe possible uses for graphenes in the future | Because of its excellent conductivity, it could be used for computer chips. Because it is flexible, it could be used for flexible display: a flexible phone! |
Created by:
ursulinechem2
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