chapter 3 - bonding. Flashcards
(29 cards)
ionic bonds are stronger and MP are higher when ions are? (x2)
ions are smaller AND/OR have a higher charge.
why do ionic compounds tend to dissolve in water?
water molecules are polar. water attracts both (+)ve and (-)ve ions in ionic compound. pulls apart - dissolves.
describe structure of graphite?
C to THREE other C. 4th e- is DELOCALISED. VDW forces between layers of hexagons.
properties of graphite?
- low density
- conductor
- INSOLUBLE!
- high BP
- layers slide
why does graphite have low density?
layers far apart compared to covalent bonds.
why is graphite insoluble?
covalent bonds too strong to break by water.
what is the structure of diamond?
C to FOUR other C.
Tetrahedral.
properties of diamond?
- high MP
- hard
- thermal conductor
- NOT electrical conductor
- insoluble
why is diamond a good thermal conductor?
stiff lattice so vibrations travel easily.
dative covalent bond definition?
when shared pair of electrons come from only one of the bonding atoms (OWTTE).
describe metallic bonding in 3 steps.
- delocalised electron free to move.
- positive metal ion has electrostatic attraction to delocalised electron.
- lattice.
why are metals good thermal conductors?
delocalised electrons can transfer kinetic energy.
why are metals insoluble?
strong metallic bonds.
factors determining strength of metallic bond?
- proton number
- no. e- per atom
- size of ion
what does shape of molecule depend on?
no. pair of electrons in outer shell central atom.
define charge clouds?
area where there is a high chance of finding a pair of e-.
why do bond angles between decrease?
lone pair repulsion.
shape of lone pair charge clouds
bond angle of linear?
180’
3 B.P
trigonal planar.
120’
bond angle of tetrahedral?
109.5’
3 B.P & 1 L.P
trigonal pyramidal.
107’
2 B.P & 2 L.P
bent
104.5’
how many degrees do you take off for each new lone pair?
2.5’
5 B.P
trigonal bipyramidal
120’ & 90’
