p block (G16-18) Flashcards
how does metallic character change down G16 and why?
metallic character increases due to the decrease in ionization energy
under what circumstance does oxygen have a positive oxidation state?
when it bonded to a more electronegative element (eg. Flourine)
why does O2 not oxidise and what can be done to overcome it?
high kinetic energy barrier which can be overcome by increasing the temperature
why must 2 molecules of O2 be required to see the pale blue oxygen in liquid form
so that there is no overall change in spin
what are the 2 allotropes of oxygen
ozone and dioxygen
what are the 2 ways of forming ozone?
- electrical charge from thunderstorms
- UV radiation
both react with O2 to form O radical which reacts with another O2 to form ozone
what is the function of ozone
- absorbs UV region to protect the planet’s surface
- used in water purification (as it is more reactive/better oxidizing agent)
- forms part of urban smog
what are the allotropes of sulphur and which one is the most stable
S5-S12 rings and S8 is most stable
which element in G16 is the best at catenation and why?
sulphur because everything beyond that is too big thus poorer overlap and oxygen has the most LPLP repulsion as it is the closest together
what are the 2 states of selenium and tellurium
Se: silver grey metal (helical polymeric chains), red powder
Te: silvery white crystalline and amorphous black powder
Why does the oxidation state increase going down G16
except for oxygen, all other elements can promote their electrons into low lying d orbitals (2x p -> d) and (1x s -> p)
2 reasons for oxygen forming more oxides than nitrogen
- oxygen is more electronegative
- O2 has lower bond dissociation energy than N2
what are the 2 ways of forming water?
- Direct reaction of its elements
- Electrolysis
Why do the heavier elements form hydrides that are 90 degrees rather than bent (105-109)
More p character (orthogonal) than s character so not fully sp3 hybridized
How to the boiling points of G16 hydrides change down the group
Water has hydrogen bonding, then from H2S it increases as VdW interactions increases
what is the difference between boiling point and thermal stability
boiling point: intermolecular interactions
thermal stability: intramolecular interactions (bond strengths)
how does thermal stability change down G16 and why?
decreases down the group due to poorer orbital overlap
how does acidity change down G16 and why?
increases down the group as poorer overlap means that the hydrogen is more readily deprotonated (donated)
what is the most inert sulphur halide and why?
SF6:
1. all of sulphurs available orbitals are used for bonding
2. steric protection due to octahedral geometry (difficult to access central atom)
3. S-F are in the same period thus orbital overlap is very strong (strong bonds)
4. greater ionic contribution (as F is very electronegative)
why is SF4 so reactive?
open face is easy to attack (due to its structure) -> see saw
what is the structure of sulphites and sulphates and which one is more reactive
sulphite: SO3 with 1 double bond + lone pair (more reactive)
sulphate: SO4 with 2 double bonds
how is SO2, SO3 and their corresponding oxoions (SO3- and SO4-) produced?
CaSO4 + C to make CaO CO and SO2
under a vanadium oxide SO2 becomes dynamic equilibrium with SO3
oxoanions can be formed by reacting the oxides with water in acidic conditions
when would flourine have a 0 oxidation state?
in its elemental form (diatomic)