Nonmetals
Ashton Lokar
AP Chem
The Nonmetals are:








Hydrogen (H)
Helium(He)
Carbon (C)
Nitrogen (N)
Oxygen (O)
Fluorine (F)
Neon(Ne)
Phosphorus (P)









Sulfur (S)
Chlorine (Cl)
Argon (Ar)
Selenium (Se)
Bromine (Br)
Krypton (Kr)
Iodine (I)
Xenon (Xe)
Radon (Rn)
Reactivity of Nonmentals


Nitrogen is least reactive due to triple
bonds that hold the N2 molecule together
A large exothermic reaction occurs giving
off hundreds of kilojoules of energy when
the N2 molecule is broken, this is why
explosives commonly contain nitrogen
Reactivity of Nonmetals (cont.)




Fluorine is the most reactive element because of
the weakness of the single bond in the F2
molecule
It has an E * red of +2.889 V
It bonds with all elements except for He, Ne and
Ar
It even bonds with water which means reactions
of compounds containing fluorine reacting with
water cannot occur
Reactivity of Nonmetals (cont.)



Chlorine is slightly less reactive than
fluorine
It still reacts with most metals
Heat is often required to induce reactions
Occurrence and preparation




3 Nonmetals: oxygen, nitrogen and sulfur
occur in nature such as in the earth and in
the air
Fluorine is found in minerals
Chlorine is found in underground deposits
of rock salt
Bromine is found in brine wells
Allotropy






By definition allotropy is when two or more structural
forms of an element in the same phase occur in a
reaction
Ex. 2O3(g) -> 3O2(g)
Phosphorus has several allotropes
2 most common: red phosphorus and white phosphorus
Sulfur can have more than 20 allotropic forms in its solid
state, this is done by solid sulfur forming different
crystalline structures
Ex. S8(rhomibic)-> S8(monoclinic)
Examples of Allotropy Problems



For the allotropic conversion P(white)->
P(red) H is -17.6 KJ and S is -18.3 J/K
At what temperature are the two
allotropes in equilibrium?
Taking that H = TS :
T= H/S = -17.6 KJ/-.0183KJ/K = 962K
or 690 degrees C
Hydrogen Compounds of the
Nonmetals
(Classified by Group)
Group 15
Group 16
Group 17
Ammonia, NH3(g)
Water, h20 (l)
Hydrogen fluoride,
HF(g)
Hydrazine,
N2H4(l)
Hydrazoic acid,
HN3(l)
Hydrogen
peroxide, H2O2 (l)
Phosphine, PH3(g) Hydrogen Sulfide,
H2S (g)
Diphosphine, P2H4
(l)
Hydrogen chloride,
HCl(g)
Hydrogen bromide
, HBr(g)
Hydrogen iodide,
HI(g)
Oxygen Compounds of Nonmetals
Group 15
Group 16
Group 17
N2O5(g), N2O4(g),
NO2(g)
OF2(g) O2F2(g)
N2O3(d), NO(g),
N2O(g)
Cl2O7(l), Cl2O6(l)
P4O10 (s), P4O6(s)
SO3(l), SO2(g)
ClO2(g), ClO(g)
BrO2(d), BrO(d),
I2O5(s),
I4O9(s),I2O4(s)
Reactions of Nonmetal Oxides with
Water



When many nonmetals react with water
acids are formed
These acids are called acid anhydrides
Ex: SO3(g) +H2O(l) -> H2SO4(l)
Oxoacids and Oxoanions
Group 15
Group 16
Group 17
H2SO4, H2SO3
HClO4, HClO3, HClO2,
HClO
HNO3, HNO2
H3PO4, H3PO3
HBrO4, HBrO3, HBrO
HIO4, H5IO6, HIO3,
HIO
Acid Strength




Increasing Oxidation number of the central atom
(HClO< HClO2< HClO3<HClO4)
Increasing electronegativity of the central atom
(HIO<HBrO<HClO)
X is a highly electronegative atom such as Cl
Additional, strongly electronegative oxygen
atoms are bonded to X
Oxidizing and Reducing Strength
1.
2.
A species in which a nonmetal is in its highest
oxidation state can act only as an oxidizing
agent, never as a reducing agent. Ex: ClO4 –
ion, where chlorine is in its highest oxidation
state, +7
A species in which a nonmetal is in an
intermediate oxidation state can act as either
an oxidizing agent or a reducing agent
Ex: ClO3- is a much stronger oxidizing agent
(E*red = +1.442 V) than reducing agent (E*ox
= -1.226 V)
Oxidizing and Reducing Strength
(cont.)
3. Sometimes, with a species such as ClO3-,
oxidation and reduction occur together, resulting
in disproportionation:
Ex: 4ClO3-(aq) -> 3ClO4-(aq) +Cl-(aq) E* =
+0.216 V
In general a species in an intermediate oxidation
state is expected to disproportionate if the sum
E*ox +E*red is a posotive number
Oxidizing and Reducing Strength
(cont.)



4. The oxidizing strength of an oxoacid or an
oxoanion is greates at high [H+] (low pH).
Conversely, its reducing strength is greatest at
low [H+] (high pH)
- when ClO3- acts as an oxidizing agent, the H+
ion is a reactant, so increasing its concentration
makes the process more spontaneous
- when ClO3- acts as a reducing agent, the H+
ion is a product; to make the process more
spontaneous, [H+] should be lowered