C3 complete Flashcards
What are intermollecular forces?
All of these substances have very strong covalent bonds between the atoms, but much weaker forces holding the molecules together. When one of these substances melts or boils, it is these weak ‘intermolecular forces’ that break, not the strong covalent bonds.
What are delocalised electrons and where are they present in metallic bonding?
Delocalised electrons are electrons which are free to move and are present around the outer shell of metal atoms.
What are the properties of metallic bonding?
- Strong electrostatic forces between metal ions and delocalised electrons
- High melting and boiling points
- Solid
- Layers of atoms can slide off each other.
What do ionic equations show?
Ionic equations show the useful bits to reactions
-Cross out equations the same on both sides
What are displacement reactions?
More reactive metals displace the less reactive metals.
What happens when you react an acid and a metal?
Acid+metal > salt + hydrogen
Easier a metal atom loses its outer shell and forms a positive ion the more reactive it will be.
What happens when you react an water and a metal? Which type of metals can react with water?
Water + metal > metal hydroxide + hydrogen
Only very reactive metals.
Which metals in the reactivity series can be extracted using carbon?
Metals below carbon can be displaced by carbon and carbon gains oxygen.
Some metals have to be extracted by electrolysis. Which metals and explain how this works.
Name one problem.
Metals more reactive than carbon are extracted using electrolysis of molten compounds. Metal melts and electric current then passes through it. Metal discharged at cathode, Non-metal at anode. BUT this is very expensive
What is phytoextraction?
Growing plants in soil which contain metal compounds
-The plants can’t get rid of the compounds so they gradually build up in leaves
The plants can be burnt-the ash will contain metal compounds which can be extracted
What is bioleaching?
Using bacteria to convert insoluble compound in the ore to soluble compounds, separating the metal and the ore
What happens in a redox reaction? (OILRIG)
Electrons are transferred.
What do half equations show? (2)
Half equations show the movement of electrons. They also show if things have to be oxidised or reduced.
e.g Na > Na+ + e-
What does electrolysis literally mean?
When is it used?
Splitting up with electricity.
Used when the metal is too reactive to be reduced by carbon.
What happens at the cathode during electrolysis?
Cathode reduces, gains electrons.
What happens at the anode during electrolysis?
Anode oxidises and loses electrons.
What is the overall equation for electrolysis?
Aluminium oxide -> Aluminium + Oxygen
What happens at the cathode in an aqueous solution?
If H(+) ions and metal ions are present, hydrogen gas will be produced if the metal is more reactive than hydrogen If the metal is less reactive than hydrogen, the metal will be produced.
What are covalent bonds?
2non-metal atoms bonded together, sharing pairs of electrons to make covalent bonds.
How can you show covalent bonds?
Dot and cross diagrams.
What are the properties of simple covalent substances?
- Simple molecular substances
- strong covalent bonds
- weak forces
- weak intermolecular forces - melting and boiling points very low = easily parted.
- don’t conduct - no free electrons
What is the empirical formula?
It is the simplest ratio of atoms.
What is the homologous series?
A homologous series is a family of molecules which share the same general formula and functional group - they have the same chemical properties.
What happens to properties as the carbon chain gets longer?
- The shorter the chain, the more runny they will be
- The shorter the chain, the lower the boiling point
