Chapter 3.4 - Bonding And Physical Properties Flashcards
State the properties of graphite
- Slippery
- Can conduct electricity
- High mp
- Insoluble
Explain why graphite is slippery
Weak bonds between the layers in graphite are easily broken, so the layers can slide over each other
Explain why graphite is a good conductor of electricity
Graphite has delocalized electrons which carry charge
Explain why graphite has a high mp
Because of the strong covalent bonds in the hexagon sheets graphite has a very high mp
Why is graphite insoluble ?
The covalent bonds in the sheet are too strong to break
Describe the bonds in diamond
Each carbon atom is covalently bonded to four other carbon atoms forming a tetrahedral shape
State the properties of diamond
- high mp
- hard
- good thermal conductor
- can’t conduct electricity
- insoluble
Explain In terms of its structure and bonding, why nickel conducts electricity
- metallic bond,
- strong attraction between positive ions and delocalized electrons
Explain why CHF3 has a higher mp than CF4 (3)
CHF3 contains polar bonds,
There are permanent dipole ,
CF3 contains polar bonds but they cancel each other out due to the shape, there are van daar waals forces between them
Therefore CHF3 has strong intermolecular forces requiring more energy to break dowm
Give the name of the type of crystal structure shown by silicon dioxide
Giant covalent structure
Explain why silicon dioxide does not conduct electricity when molten
No delocalized electrons
Deduce why the bonding in nitrogen oxide is covalent rather than ionic
Small electronegativity difference
Suggest why graphene is an excellent conductor of electricity.
- It has Delocalized electrons,
- Able to move
Explain, in terms of its structure and bonding, why graphene has a high melting point (2)
- Covalent bonds,
- Many /strong / hard to break / need a lot of energy to break
Name the type of bonding in the element sodium
Metallic
Suggest why titanium can be hammered into different shapes.
Layers can slide over each other
Suggest why these objects with different shapes have similar strengths
Strong metallic bonding re-formed
Explain, in terms of its structure and bonding, why titanium has a high melting point. (2)
- positive ions and delocalised electrons are attracted,
- strong attraction
Magnesium oxide (MgO) has a melting point of 3125 K.
Predict the type of crystal structure in magnesium oxide and suggest why its melting point is high.
Type of crystal
Explanation
- giant ionic,
- strong attraction between oppositely charged ions
Explain why the melting point of sodium chloride is high
- ionic bond,
- strong attraction between ions of opposite charges
Explain in terms of bonding why KBrF has a high melting point
- ionic bond,
- strong forces of attraction between oppositely charged ions
Explain, in terms of structure and bonding, why the melting point of carbon is high (3)
- macromolecular,
- covalent bonds in the structure,
- covalent bonds need a lot of energy to break
Describe the bonding in a metal (2)
-positive ions attracted to delocalized electrons
Explain each of these properties of diamond and graphite in terms of structure and
bonding. (6)
Diamond
- atoms in diamond joined to 4 other carbon atoms forming a tetrahedral shape
- diamond is hard and strong bcoz of its 3D shape,
- giant covalent structure
Graphite
- giant covalent structure
- atoms in graphite joined to 3 other carbon atoms forming a Trigonal planar shape,
- graphite is soft as layers can slide over each other
Give one other difference in the properties of diamond and graphite.
diamond is non-conductor of electricity, graphite is conductor
Why do diamond and graphite both have high melting points ?
- giant covalent structure
- strong covalent bonds
Why is graphite a good conductor of electricity?
It has delocalized electrons
Why is graphite soft ?
Layers can slide over each other
Describe the bonding in a crystal of iodine (2)
- van der waals between molecules,
- covalent bonds between atoms
In terms of its structure and bonding, suggest why graphite has a very high melting point (2)
- macromolecular
- strong covalent bonds
State the type of structure present in each case and explain why the melting point of diamond is so high.
-diamond is a macromolecular
C-C bonds need to be broken which takes a lot of energy bcoz bonds are strong
Describe the bonding in, and the structure of, sodium chloride and ice
- NaCl is ionic,
- strong attraction between ions of opposite charge
- covalent bonds between atoms in water
- hydrogen bonding between water molecules
- covalent bonds in ice are strong
- tetrahedral
Explain how the ions are held together in solid sodium metal
Strong attraction between positive ions and delocalized electrons
Explain how the ions are held together in solid sodium chloride.
- ionic bond,
- strong attraction between ions of opposite charge
Compare the electrical conductivity of solid sodium metal with that of solid sodium chloride. Explain your answer.
Comparison,
Explanation
- sodium conducts and NaCl doesn’t,
- sodium has delocalized electrons that carry charge,
- ions cannot move in NaCl but can when molten
State the type of crystal structure for each of iodine and graphite.
Iodine- molecular ,
Graphite- giant covalent/macromolecular
Describe the structure of and bonding in graphite and explain why the melting point of graphite is very high.
- Layers of C-C bond connected by covalent bonds,
- van der waals forces between layers,
- strong covalent bonds need to be broken down
Explain why iodine vaporises when heated gently
Van der waals forces between molecules are weak
