Structure Flashcards
Giant structure
Regular repeating pattern of ions (or atoms) , known as a lattice. Each ion/atom is held in place by strong chemical bonds
Simple structure
Small molecules which are strongly bonded inside the molecule and have different levels of intermolecular bonding between molecules
Metals - MP+BP
HIGH
- Strong electrostatic forces between + ions and delocalised - electrons
- High amount of energy needed to break
Metals - Conduction
CONDUCTIVE
- Free moving/mobile/delocalised electron can carry charge
Metals - Solubility
INSOLUBLE
(In any solvent)
Giant Ionic - MP+BP
HIGH
- Strong electrostatic attraction between oppositely charged ions
- High amount of energy needed to break
Ionic - Conductivity
CONDUCTIVE if aqueous or molten
- Ions are mobile - carry charge
NOT CONDUCTIVE if solid
- Ions are fixed in place in lattice
Giant Ionic - Solubility
SOLUBLE in POLAR solvent
Ex: H2O - δ+ H attracts anions
(O more electronegative/asymmetrical molecule) δ - O attracts cations
➡️ ions pulled away from lattice + dissociate (dissolves)
INSOLUBLE in NON polar solvent
Giant covalent structures
Lattice of covalently bonded atoms, ‘macromolecular structure’
Diamond
- 4 bonds per C ➡️ tetrahedral
- HARD, HIGH MP+BP - strong covalent bonds
- NOT conductive - localised e-
- INSOLUBLE in any solvent - attractions between solvent molecules never strong enough to overcome diamond covalent bonds
Graphite
- 3 bonds per C (hexagonal sheets)
- HIGH MP+BP - strong covalent bonds between atoms
- CONDUCT - delocalised e- (3 bonds)
- INSOLUBLE - (same reason as diamond)
- Sheets bonded by weak temporary dipole dipole forces
Graphene
- one atom thick layer of C atoms (pure form of C)
- Strong for low weight
- CONDUCTIVE - delocalised e- (potential use in electronics)
Silicon
- HIGH MP+BP, hard - strong covalent bonds between atoms
-NOT conductive - localised e-
Physical properties of simple molecular structures determined by…
Bonding BETWEEN molecules
3 types of intermolecular forces
- Induced dipole dipole (London forces)
- Permanent dipole dipole
- Hydrogen bonding
Iodine MP+BP
- LOW MP+BP - little energy needed to break the weak temporary induced dipole dipole attractions between molecules (sometimes sublimes at low temperature)
Iodine conductivity
NOT conductive - no mobile ions/delocalised e-
Iodine Solubility in Polar Solvents
Partially soluble
- simple structures unable to break H bonds in h2o + unable to make H bonds with polar water molecules ( solution turns light brown)
Iodine solubility in non-polar solvents
Soluble
- simple structures are able to break weak induced dipole dipole between NP solvents
- simple structures are able to make induced dipole dipole bonds with NP solvents
(Solution turns purple)
Structure of Silicon
Giant covalent
What are ionic bonds always stronger than
Shape of molecule determined by?
Shape of molecule is determined by electron repulsion theory as lone pairs repel more than bond pairs. Electron pairs repel as far as possible
AgBr in water? Meaning?
AgBr is insoluble in h2o → ions remain fixed in giant lattice → cannot carry charge/conduct electricity in h2o
