Section 1 - Key concepts - Ionic, covalent and metallic bonding Flashcards
What are anions and cations?
Which of metals and non-metals form which one?
Anions- negative ions
Cations - positive ions
Metals and hydrogen form positive ions
Non-metals except hydrogen form negative ions
What is ionic bonding?
Metal and non-metal react together to form oppositely charged ions and are strongly attracted to each other by electrostatic forces of attraction in all directions
Type of structure in ionic compounds?
Giant ionic lattice structure. Ions form closely packed regular lattice
Why do ionic compounds have high melting and boiling points?
Due to strong forces of attraction between ions. Requires large amount of energy to overcome this
Why do solid ionic compounds not conduct electricity and why they do when melted or dissolved in water?
When solid, ions fixed in place and can’t move. When melted or dissolved, ions free to move and will carry electric current.
What are simple molecular substances made up of?
Made up of molecules containing few atoms joined by covalent bonds
Why do covalent simple molecular compounds have low melting and boiling points?
Atoms within molecules held together by very strong covalent bonds, but forces of attraction between these molecules are very weak
Why do covalent molecular compounds not conduct electricity?
They don’t contain any free electrons or ions
What are polymers? How are they formed?
Molecules made up of long chains of covalently bonded carbon atoms. Formed when lots of monomers join together
Why do giant covalent structures have very high melting and boiling points?
All atoms bonded to each other by strong covalent bonds so lots of energy needed to break the covalent bonds
4 structures of diamond?
- Each carbon atom forms 4 covalent bonds
- Strong covalent bonds
- Rigid lattice structure
- No free/delocalised electrons so doesn’t conduct electricity
4 structures of graphite?
- Each carbon atom forms 3 covalent bonds
- Arranged in hexagons
- No covalent bonds between layers
- Each carbon atom has one delocalised electron so conducts electricity
What is graphene?
One layer of graphite, arranged in hexagons. One atom thick
What are fullerenes?
Molecules of carbon shaped like closed tubes (nanotubes) or hollow balls (buckminsterfullerene)
How do fullerenes make great industrial catalysts?
They have huge surface areas
