Chapter 2: Strong Bonding Flashcards
Metallic Bonding
- Electrostatic attraction between positive ions and a sea of delocalised valence electrons that holds the positive ions together.
- Strength of bonds depend on
- > charge of +ive ions
- > more valence e- = stronger bonds
- > size of ions
- > way in which ions arranged
Physical properties of metals
- high electrical conductivity -> delocalised, mobile charge carriers
- heat conductivity -> delocalised, mobile e- transfer kinetic energy
- malleable and ductile -> layers of +ive ions move when metal bent stretched, delocalised e- move into regions b/w and keep structure
- lustre -> interaction b/w photons of light and mobie e- sea
high mp -> +ive ions w/ larger charge have stronger bonds
Alloys
Same basic structure w/ impurities incorporated into lattice
- the impurity disrupts orderly nature, more difficult for layers to slide therefore harder and stronger
Ionic Bonding
Electrostatic attraction b/w positive and negative ions
- Transfer of electrons / lose electrons and gaining electrons
- arranged in orderly lattice
- > metal loses e’ due to low ionisation energy
- > non-metal gain e’ due to high electronegativity
Physical properties of ionic bonds
- Non conductors in solid state -> ions held in rigid lattice are not mobile
- Conductors in molten/ soln -> ions break away from rigid lattice and become mobile. Act as charge carriers free to move.
- Hard and brittle -> Bonding holding ions in lattive strong therefore hard. When put under pressure, layers of ions pushed causing like charges in close proximity therefore fall apart
High mp and bp -> Much energy required to overcome forces
Covalent Molecular Bonding
Electrostatic attraction b/w adjacent nuclei and shared valence electrons
physical properties of covalent molecular bonding
low MP and BP -> covalent bonds b/w atoms are strong BUT bonds b/w molecules are weak
- Solids are soft -> bonds b/w molecules are weak therefore little force required
Do not conduct -> neutral molecules, e- and protons are localised
Covalent Network Substances
- atoms bonded together by shared e- pairs
- Bond together in vast lattice arrays not just discrete molecules
Physical Properties
High mp/BP -> each atom held in lattice by very strong covalent bonds, much energy required
- Extremely hard and brittle -> atom held in lattice by strong covalent bonds. One area disrupted strains rest of lattice and falls apart
- Non conductors -> e- are localised in pairs around each atom