crev Flashcards
ep why ions dif size 2 atoms
+ smaller: 1 less e- shell, attraction of nucleus shared bn less e-s so pulled in closer
- larger: attraction of nucleus shared over more e-s so x pulled in as close
ds e- density map (https://chemrevise.files.wordpress.com/2018/11/2-bonding-edexcel.pdf p2
atom surrounded by rings - e p on ring has = e- density
sf e- density map;
x shows edge of ion so hard 2 measure rd
e- density bn atoms: covalent, ionic
ionic: 0, covalent: hi
why multi bond shorter len, stronger
hi e- density so greater attraction bn e-s a nucleus
df compound containing 2 similar units
dimer
bond angle 7 compound shapes
linear=180 trig planar=120 tetrahedral=109.5 trig bipyramidal=120 a 90 octahedral=90
bent(2 bonds+ 2 e- pairs)=104.5 trig pyramidal(3 bonds+ 1 e-pair)=107
df electro- vity
how much atom in covalent bond attracts e-s 2 itself
ds ionic-> covalent scale
covalent v small electro-vity dif
polar 0.3-1.7
ionic >1.7
which mols arent polar
symmetrical
ds alcohol a soluble
smaller alcohol soluble (c fm H bonds w wr)
t longer t C chain t less soluble
df hydration enthalpy
heat en released when bond fm w wr
dissolving rule
y if similar intermolecular F eg iodine in hexane as only dispersion forces
factors affecting metallic bond stren
num protons
delocalized e- per atom
size of ion (eg radius)
//proton, e-, ion
draw iodine, wr mols
io: I2 mols, weak bonding (London F) 2 otr I2 mols
wr: 2 covalent bonds 2 Hs, 2 hydrogen bonds
why graphite x conduct electricity bn layers
large en gap bn layers
why simple molecular bad conductor
no ions 2 conduct, localized e-
gp2 melting p trend
decrase down gp- atomic size up so dist bn + ions up so weaker electrostatic forces
gp2 1st ionization en trend
decreases down gp- more shells so outermost further from nucleus, repulsion from inner e- shells oppose attraction from nucleus
gp2 reactivity trend
increases down gp- ec 2 remove e- a so 2 form cations
list gp 2 rxns
w Cl-> MgCl2
Mg w steam or otrs w cold wr: Mg ( white flame)+H2O-> MgO+H2
Mg w wr: Mg+2H2O-> Mg(OH)2+ H2
list gp 2 oxides rxn
w wr: MgO+H2O->Mg(OH)2
w acid:MgO+ 2HCl->MgCl2+H2O
substance used 2 neutral excess stom acid, why
Mg(OH)2 as v weak alkaline
gp 2 sulfate trend
less soluble down gp- metal sulfates produced insoluble a coat surface of metal as it reacts
ds thermal decomposition gp2 (x nitr8
gp2 carbonate-> gp oxide +CO2
ep trend thermal decomp gp2
more en req as more thermally stable bigger cation (weaker +) so compounds x as polar so carbonate less distorted so C-O bond weakened less
ep gp1 thermal decomp
won’t decompose
only +1 charge so x polarize Carbonate ion
(except Li as small
equation gp2 Nitr8 therm decomp
2Mg(NO3)2 -> 2 MgO + 4NO2 + O2
observation gp2 nitr8 therm decpn
brown gas appears (NO2), nitr8 solid melt 2 colourless solution then resolidify
td gp1 nitr8 eq
2Na NO3->2NaO2 +O2 (Li td lk gp2 eles
ep why flame test wks
heat cause e- move -> higher en level
e- unstable at lvl so move down, emitting en in fm of light as does so
nature halogen
F-pale yellow
Cl=green,
Br=red lqd, gives offf brown/ orange fumes,
I=shiny grey solid sublime to purple gas
peas a sweetcorn, go 2 volcano, 2 discard grey sword
halgon trend et-
ds trend elecctr- halogne; decrease down gp
as atomic radii up as more shells so more dif 2 attract e-
e- wants 2 catch otrs z get bigger so cant
colour solution w: Cl br I (in wr a in organic solvent
wr: pale green, yellow, brown
solvent: colourless, yellow, purple
ds oxidization of metals by halogens
Cl, Br c oxidize Fe2+ -> 3+,
I- reduced 3+-> 2+
eq 1 eg disporoprtionation
Cl + wr -> HClO + HCl
ds rxn NaOH a halogen
cold NaOH: NaCl+ NaClO + wr = colorless solution
used as bleech disinfectant
hot: NaI + NaIO3 + wr
nm NaClO, K2SO3
sodium chlorate (i) potassium sulfate(iv)
