inorganic 7- groups 16&17&18 Flashcards
why cant oxygen go past the oxidation state of +2
-example of compound where O is +2
it is highly oxidising
OF2
what is the reactivity of O2, vs H2O
H2O has lone pairs, which they can donate into empty orbitals
O2 has 2 unpaired electrons and can accept 2 electrons also (into the half filled orbitals)
what is the MO diagram for oxygen
what is the bond order or O3
1.5
what is the reactivity of O3 - what is uses to react
has lone pair in the sp
-remaining sp2 form bonds
-has an empty p orbital
-the terminal oxygens have 1 e- in their p orbitals
-very reactive/ wants to loose an O to make O2
compare the reactivity of O2 and O3 (oxidation and reduction)
-both are strong oxidising agents
O2 is very favourable to undergo reduction (positive E cell value) so strong oxidising agent
-O3 is a stronger oxidising agent because it has a higher E value
why is O3 and better oxidising agent?
has a higher E cell value due to bond order of 1.5 in O3 and 2 in O2
-therefore O3 can degrade easier
what is a characteristic of S and the structures it makes
S is the most allotropic element
-S-S bonds can form a lot of rings
For S8 (the most common) how does viscosity change with temperatures 120°C and 160°C
-S8 is a solid
120°C= heated to form liquid so viscosity decreases
160°C= viscosity suddenly increases due to S8 rings opening to form S16 and S24 chains
further heat- these chains break down and form smaller chains
as you go down group 16 what are the trends in
-being able to form multiple bonds
-catenation (forming a chain)
decreasing tendency to form multiple bonds
decreasing catenation
What are the forms of N and P (single/double/ triple bonds) and why
P4 is more stable than P2
N2 is most stable form of nitrogen
why does oxygen prefer to form double bonds but sulfur single bonds?
for oxygen, 1 double bond is stronger than 2 single bonds
for sulfur the single bonds are stronger than the double bonds, so it will more likely form single bonds
-more favourable to form π bonds in oxygen than S
element-element single bonds usually increase in energy across a row, why are N,O and F anomalies
-electron-electron repulsion
meaning overall weaker bond and pushing the atoms further away from each other
why does bond strength generally decrease down the group
-size of orbitals increase as atom size increases
-atom distance gets further apart
-not using all VE to form single bonds
-therefore bond strength decreases
group 16-18 hydrides
describe the trend in acidity down each group
bonds get weaker down the group
-so reduced stability and increased acidity (easier to loose the H+)
is there more or less s/p mixing down group 16
-and why is this
s/p mixing gets less down the group
-energy difference between s and p orbitals increases/ bonds become more p-like in character
down group 16 hydrides, what happens to the bond angle
s-p mixing decreases down the group so bond angles become closer to 90°
explain the trend of the boiling boiling points of group 16 hydrides
O is high due to hydrogen bonding
-then increases from O due to increased London forces
H2O2 is a reducing/oxidising agent in acidic/alkaline conditions
reducing agent = alkaline solution
oxidant agent= acidic solution
what does this show
oxidant agent= acidic solution
reducing agent= alkaline solution because E value Is negative and so reaction will go in the other direction (reduction)
what are the 2 hydrides of oxygen
H2O and H2O2
why is H2O2 kept in cold conditions
to stop is going into a disproportionation reaction
what is the only halide oxygen can form
fluorides which are highly reactive
why does OF2 rapidly decompose on formation
O-F bond is long and very weak
