Ionic Bonding
Covalent Bonding
Metallic Bonding
Giant Carbon Structures
Smart Materials and Nanotechnology
100
Give an example of an ionic compound.
Any sensible suggestion
100
Give an example of a covalently bonded molecule.
Any sensible suggestion
100
What charge does a potassium atom have once it is bonded via metallic bonding to other potassium atoms?
+1
100
Name two giant carbon structures.
Diamond/graphite/buckyball/graphene etc
100
Name two types of smart material.
Shape memory polymer, shape memory alloys, photochromic materials, thermochromic materials, hydrogels
200
What do we call an atom that has lost or gained an electron and now has either a positive or negative charge?
An ion
200
Covalent bonding happens between ...................... (what type of elements?)
Covalent bonding happens between two non metals
200
Metal atoms (or positively charged ions) are held together by a ....................................
Metal atoms (or positively charged ions) are held together by a sea of electrons.
200
What shape is buckminsterfullerene?
Ball or spherical
200
Why would some people be against the use of silver nanoparticles?
Easily penetrate the body, could cause side effects, easily released into the environment, more research is needed to fully understand them.
300
List three properties of ionic compounds.
-Made of crystals (as they form lattices)
-High melting points/high boiling points
-Often soluble in water
-Conduct electricity when molten
300
Why does methane (CH4), a simple covalent structure have a much lower melting point than a giant covalent structure like diamond?
As they are only small molecules, the forces between the molecules is weak and can be overcome easily. With giant covalent structures, you need to break all the covalent bonds before it turns to a liquid.
300
Draw a diagram to show metallic bonding.
300
Explain why graphite can conduct electricity.
Each carbon atom is bonded to three others, so each atom has a free electron, resulting in a sea of electrons that can carry electrical charge.
300
How small is a nanometre?
One billionth of a metre
400
Why would an ionic compound with magnesium have a higher melting point than a compound with sodium? (Hint: think of group number, and what this means for the ions formed)
Magnesium is in group 2, whereas sodium is in group 1. When magnesium forms an ionic compound it becomes a 2+ ion, and so the attraction to the negative ion in the compound is much stronger, and hence the melting point will be much higher.
400
Draw the covalent bonding as a dot-cross diagram for NH3
400
Explain why metals can conduct electricity.
Metals conduct electricity because they have “free electrons.” Unlike most other forms of matter, metallic bonding is unique because the electrons are not bound to a particular atom. This allows the delocalized electrons to flow in response to a potential difference.
400
List two uses of nanotubes.
Drug delivery systems, as catalysts, to reinforce materials, as lubricants for machinery
400
Explain what thermochromic and photochromic smart materials do.
Thermochromic: materials that change colour as a result of temperature
Photochromic: materials that change colour as a result of light
500
Draw a dot-cross diagram to show the ionic bond in the compound Li2O.
500
Draw the covalent bonding in O2 as a dot-cross diagram.
500
List six properties of metals.
-Shiny
-Malleable
-Ductile
-Hard
-Dense
-Can conduct electricity
-High melting and boiling points
500
Draw the giant covalent structure of graphite.
Points for layers and hexagon shapes
500
Name two compounds that are used as nanomaterials.
Silver, zinc oxide, titanium oxide