C2 - Structure and Bonding Flashcards
What is metallic bonding?
The bonding between metals
How does metallic bonding occur?
Lattice structure of positive ions surrounded by sea of delocalised electrons. They attract each other as they are oppositely charged
Why can metals conduct electricity and heat?
Electrons are free to move THROUGH the structure to carry a charge
What is ionic bonding?
Bonding between metals and non-metals
How does ionic bonding occur?
Metal atoms donate electrons to form positive ions. Non-metal takes electron to form negative ions
How can we show ionic bonding?
Dot and Cross diagram
What do the charges of all ions have to add up to in an ionic compound?
0
Structure of ionic structures
Lattice of repeating units positive and negative ions which form a crystal
Properties of ionic structures
-High melting and boiling point due to strong electrostatic forces
-Conduct electricity when molten or dissolved because ions are free to move and carry charge
-
Formula for hydroxide ions
OH-
Formula for sulphate ions
(SO4)2-
Formula for carbonate ions
(CO3)2-
Formula for nitrate ions
(NO3)-
Formula for ammonium ion
(NH4)+
What are ionic compounds also known as?
Salts. e.g. sodium chloride
Positive ions are known as…
Cations
Negative ions are known as…
Anions
What is covalent bonding?
Bonding between non metals
In covalent bonding are electrons shared or transferred
Shared
In ionic bonding are electrons shared or transferred
Transferred
What are simple covalent structures?
Covalent molecules with a small number of atoms
Properties of small covalent structures
-Low melting and boiling points, weak electrostatic forces
-Can’t conduct electrical
What is a giant covalent structure? Give an example
Structures that consist of repeating units of atoms, essentially creating giant molecules
- diamond, silicon dioxide
What is a giant covalent structure?
Structures that consist of repeating units of atoms, essentially creating giant molecules
Properties of a giant covalent structure
- Very high melting and boiling points as you have to break the strong COVALENT bonds
Properties of diamond
-Very hard
-High melting and boiling point as you have to break very strong covalent bonds
- Can’t conduct electricity
- Each carbon is bonded to 4 other carbons
What is an allotrope?
Structures made of the same element but structured differently
Describe the structure of graphite
-Layers of carbon with 3 bonds each
- Layers can slide over each other
- Delocalised electrons form weak bonds between layers, so can conduct electricity
Can graphite conduct electricity?
Yes
What is graphene?
A singular layer of graphite
Why are metal alloys stronger than pure metals?
Different size atoms disrupt the lattice, so layers cannot slide over each other as easily - strong!
What are fullerenes/nanotubes? Name an example
3d structures of carbon atoms
- Buckminster Fullerene (made of 60 carbon atoms)
Uses of fullerenes/nanotubes
-Electronics
-Composites
- Medical purposes (delivering drugs into body)
How many nanometres (nm) are there in a nanoparticle?
1-100 nm
Size of fine particles in nm
100-2500 nm
Size of coarse particles e.g. dust
> 2500 nm
Why are fullerenes useful? In terms of surface area: volume ratio
High surface area to volume ratio, so fewer are needed for purpose
