Structures Flashcards
What is the structure of the giant ionic lattice?
Strong electrostatic forces attraction between oppositely charged ions
What is the bonds between giant ionic lattice?
Ionic bonds
Why is there high boiling and melting points in a giant ionic lattice?
High melting and boiling points because substantial amount of energy is needed to break the strong ionic bonds
Can giant ionic lattices conduct electricity?
In solid state the negative ions cannot move or carry charge therefore don’t conduct electricity. However if the ionic solid is melted it can move and carry charge
Are giant ionic lattices soluble in water?
Most ionic compound are soluble in water and form aqueous solutions
What is the structure of molecular covalent structures?
Strong covalent bonds between compounds with weak van set waal forces between the molecules
Why is there low melting and boiling points in a molecular covalent structure?
Little energy is needed to break the weak forces between the molecules so there is low melting and boiling points
Does molecular covalent bonds conduct electricity?
The covalent molecular substances do not conduct electricity because the molecules are neutral and there are no charged particles (ions or neutrons) to move and carry charge
Are molecular covalent structures soluble in water?
Insoluble in water as they don’t form intermolecular bonds with water
What is an allotrope?
Different forms of the same element in the same physical state
What are the allotropes of carbon?
Diamond, graphite, graphene
What is the structure of a diamond?
Each carbon atom is bonded to 4 others in a tetrahedral shape
Why does a diamond have high melting and boiling points?
Substantial amount of energy is needed to break the strong covalent bonds
Does a diamond conduct electricity?
There are no free ions or delocalised electrons to move and carry the charge
Why is a diamond soo hard?
It is hard due to the 3-D tetrahedral structure with strong covalent bonds
What is the structure of graphite?
Layers of carbon arranged in hexagons with covalent bonds between atoms and weak forces between layers - one electron per carbon atom is delocalised
Why is there high boiling and melting points in graphite?
High melting and boiling points as substantial amount of energy is needed to break the covalent bonds
Can graphite conduct electricity?
It can conduct electricity sonar there are delocalised electrons which carry charge
Is graphite hard?
No
It is soft because the weak forces between the layers allow the layers to slide
What is the structure of graphene?
A single atom thick layer of graphite with strong covalent bonds between each carbon atom: the atoms are arranged in hexagons
Why are there high melting and boiling points in graphene?
High melting and boiling points because covalent bonds are strong and substantial amount of energy is needed to break it
Does graphene conduct electricity?
Good conductor of electricity as one electron per atom is unbonded and is free to carry charge
Is graphene strong?
Very strong as there are strong covalent bonds in the layers. It is light and the thinnest material possible and transparent due to the one layer of atoms
What is the structure of a metallic lattice?
A 3-D structure of positive ions and Delano slides electrons bonded by metallic bonds
So metallic lattices have high melting and boiling points?
Metals have high melting and boiling points because the metallic bond (attraction between the positive and delocalised electrons) is strong and takes substantial amount of energy to break
Are metallic lattices good conductors of electricity?
Metals are good conductors of electricity because the delocalised electrons can move and carry charge
Why are metallic lattices malleable and ductile?
Metals are malleable and ductile because the layers of ions can slide over each other, yet the delocalised electrons still attract the ions and hold the structure together - the metallic bond is not disrupted
What is an alloy?
A mixture of two or more elements, at least one of which is a metal, and the resulting mixture has metallic properties?
Why are alloys harder than pure metal?
Alloys contain ions or atoms of different sizes, which distort the regular arrangement. This makes it more difficult for the layers to slide over each other, so alloys are harder than pure metals.
Why is gold alloys used instead of pure gold?
Pure gold is rarely used in jewellery as it is too soft. Instead gold alloys are used containing other elements.
What is the purity of gold measured in?
The purity of gold is measured in CARATS ( pure gold is 24 carats)
How to measure the purity of gold?
% of gold in alloy = number of carats/24 X 100
