c2 Flashcards
name the limitations of the particle model
- All particles are represented as spheres
- Particles are represented solid and unbreakable
- We simplify the different forces between particles by calling them all bonds
what happens when when a liquid reaches boiling point
particles have enough energy to overcome forces
name the two main types of covalent structures
- simple molecules
- giant covalent structures
describe simple molecules
- low boiling point and melting point
- molecules held together by weak intermolecular forces
- covalent bonds between atoms
describe giant covalent structures
high boiling point and melting point due to strong covalent bonds which hold the structure together
why does carbon dioxide have a low boiling point
- carbon dioxide is a simple molecule
- there are weak intermolecular forces
- therefore a small amount of energy is needed to overcome these forces
why does diamond have a high melting point?
- diamond is a giant covalent structure
- there are strong covalent bonds between the carbon atoms
- therefore a large amount of energy is needed to overcome the bonds.
describe the structure of diamond
each carbon atom forms four covalent bonds with other carbon atoms
describe the structure of graphite
each carbon atom forms three covalent bonds with other carbon atoms forming layers of hexagonal rings
can diamond conduct electricity? why?
no
no delocalised electrons
why is graphite soft
soft due to weak intermolecular forces between layers of carbon so layers can slide off
can graphite conduct electricity? why?
yes
delocalised electrons move between layers carrying charge to conduct electricity
describe the structure of sodium chloride
sodium chloride consists of sodium and chloride ions arranged in a giant ionic lattice. the ions are held together by strong electrostatic forces of attraction between positive and negative ions
why do ionic compounds have high melting points?
high electrostatic forces of attraction between ions so high amounts of energy needed to overcome these forces
when can ionic compounds conduct electricity
ionic compounds can conduct electricity when molten or dissolved because the electrostatic forces are overcome so ions are separated so they are free to move within the structure and carry charge