Exam qs Flashcards
Methane is used as a fuel.
The displayed structure of methane is:
H
|
H - C - H
|
H
Write down everything that this diagram tells you about a methane molecule
- There is one carbon atom
- There are four hydrogen atoms
- A hydrocarbon - CH4
- single bonds
- covalent/shared electrons
Explain why fullerenes can be used in medicine
- Fullerenes have hollow shapes
- Fullerenes can contain drugs for a specific delivery
- Fullerene structures are strong
- This is because fullerene is based on hexagonal rings of carbon atoms
- that are covalently bonded together
State TWO ways in which the chemical elements within groups are similar
- Elements within groups have the same number of electrons
- Elements within groups have similar chemical properties (e.g. reactivity)
Explain TWO benefits and TWO limitations of using dot and cross diagrams in understanding the structure of small covalent molecules like NH3
Benefits:
- Able to see the origin of electrons in bond by the use of dots and crosses to represent them
- Able to see how many electrons take part in a bond
Limitations (any two):
- Gives no information about the shape of the molecule
- Gives no information about the 3D arrangement of atoms in space
- Gives no information about the size of the atoms involved
By reference to their structure, explain how the particles in a piece of metal are held together and how the shape of the metal can be changed without it breaking
- The electrons do not belong to specific atoms / they are delocalised
- metals atoms form positive ions
- the attraction which exists between particles with opposite charges, holds the metal together
- no specific bonds exist between adjacent atoms/ions
- atoms / ions can slide over each other so allowing metals to bend
Graphite and diamond are different forms of the element carbon. Graphite and diamond have different properties.
Graphite is softer than diamond. Explain why.
Graphite:
- because the layers (of carbon atoms) in graphite can move / slide
- this is because there are only weak intermolecular forces between layers
Diamond:
- however, in diamond, each carbon atom is (strongly / covalently) bonded to 4 others
- so no carbon / atoms able to move / slide
Compare the structure and bonding of carbon dioxide, magnesium oxide and silicon dioxide
- carbon is a simple molecular substance
- magnesium oxide is a giant ionic lattice
- silicon dioxide is a giant covalent structure
- carbon dioxide is bonded with strong electrostatic forces of attraction between the negatively charged shared pair of electrons and positively charged nuclei of the adjacent atoms but weak intermolecular forces between molecules
- However, magnesium oxide is bonded with the electrostatic forces of attraction between oppositely charged ions
- Silicon atoms are also bonded with strong covalent bonds to oxygen atoms (like carbon dioxide) but has no weak intermolecular forces
What shape is a Buckminsterfullerene molecule?
Spherical
What are the seven uses of fullerenes?
- drug delivery (round the body)
- hydrogen storage
- anti-oxidants
- reduction of bacterial growth
- catalysts
- (cylindrical fullerenes for) strengthening materials
- (spherical fullerenes for) lubricants
Explain why graphite is:
- a good electrical conductor
- soft and slippery
You should answer in term of structure and bonding [6]
Indicative content
- bonds are covalent
- giant / macromolecular structure
- three (covalent) bonds per carbon atoms
or
only three electrons per carbon atom used in (covalent) bonds - so one electron per carbon atom (is delocalised)
- these delocalised electrons can move through the structure
- carry (electrical charge)
- so graphite conducts electricity
- layered structure
- of (interlocking) hexagonal rings
- with weak (intermolecular) forces between layers
or
no (covalent) bonds between layers - so the layers can slide over each other
- so graphite is soft and slippery
Give the meaning of ‘isotope’
You should answer in terms of subatomic particles
(atoms with the) same number of protons
(but with) different numbers of neutrons
Explain why sodium oxide has a high melting point.
- giant structure
- (with) strong (electrostatic) forces of attraction between (oppositely charged) ions
- (so) large amounts of energy are needed to break the bonds / forces
Soluble salts can be produced by reacting dilute hydrochloric acid with an insoluble solid.
Copper, copper carbonate and copper oxide are insoluble solids.
Which of these insoluble solids can be used to make a copper salt by reacting the solid with dilute hydrochloric acid?
Copper carbonate and copper oxide
A solution is made by dissolving 1g of hydrogen chloride in 1dm3 of water.
Which is the correct description of this solution?
A dilute solution of a strong acid
Poly(ethene) is a thermosoftening polymer.
Suggest why poly(ethene) is easier to recycle than thermosetting polymers
poly(ethene) melts
(so) can be reshaped (into new products)
