Structures Flashcards
What does an ionic lattice consist of?
Alternate positive and negative ions in a regular arrangement
Why do ionic compounds have high melting and boiling points?
The ionic bonding is strong and requires substantial energy to break
Why can ionic compounds conduct electricity when molten or dissolved in water?
The ions can move and carry charge
Why are molecules described to have a molecular covalent structure?
The molecules contain covalent bonds and exist as simple molecules
What are the weak forces of attraction between the molecules called?
Van fed waals forces
Give three examples of molecular covalent substances:
Hydrogen, chlorine, hydrochloride acid, water, methane, oxygen, carbon dioxide, nitrogen
Why do molecular covalent substances have low melting/ boiling points?
The van fed waals forces between the molecules are weak and require little energy to break
Why can molecular covalent substances not conduct electricity?
They do not contain charged particles
What are allotropes?
Different forms of the same element in the same physical state
Name the three allotropes of carbon:
Diamond, graphite and grapheme
What is a giant covalent structure?
A regular arrangement of atoms held together by covalent bonds
Why is diamond hard?
It has strong covalent bonds and a rigid 3- dimensional structure
Why is graphite soft?
There are weak bonds between the layers so the layers can slide off
Why is graphene transparent?
It has a single atom thick layer of carbon atoms
Why does graphite conduct electricity?
It contains delocalised electrons which can move and carry charge
Why does diamond have a high melting and boiling point?
It has many strong covalent bonds which require substantial energy to break
Give a use of graphite:
A lubricant
In pencils
Why is graphene used in batteries?
It can conduct electricity and is very light
What is the structure of of a solid metal known as?
A metallic lattice
What are metals malleable?
The layers of positive ions can slide over each other without disrupting the bonding
What is an alloy?
A mixture of elements, one of which is metal and the resulting mixture has metallic properties
How is the percentage of pure gold calculated?
Carat rating/24 x 100
