INORGANIC CHEMISTRY
- Non-Metals
5TH FORM CHEMISTRY
MRS. J. THOMAS
Properties of Non-Metals
At the end of this lesson, students should be able to:
1. describe the physical properties of non-metals.
2. describe the chemical properties of non-metals.
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Physical properties of non-metals
Characteristics
Non metal
Melting point
Low except diamond and graphite
Boiling point
Low except diamond and graphite
Density
Low except diamond
Conductivity
Poor conductor of heat and electricity except
graphite
lustre
Usually lustreless (dull) except iodine and
graphite
Hardness
Not hard except diamond
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Chemical Properties of Non metal
Non-metals (sulphur) and gaseous non-metals ( chlorine, nitrogen, hydrogen
and oxygen) react with metals to form ionic compounds. Except carbon
which does not normally react with metals.
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Heating of sulphur with magnesium: Mg(s) + S(s) → MgS (s) (magnesium sulphide)
The reactions between metals and gaseous non-metals
Element
Examples of reaction with
metal
Equation
Product description
Hydrogen
Alkali metals
2Na(s) + H2(g) → 2NaH (s)
sodium hydride
Ionic compound
Na+ and H- ions
Oxygen
Reacts with all metals
2Ca(s) + O2(g) → 2CaO (s)
calcium oxide
Ionic compound
Ca2+ and O2- ions
Nitrogen
Reacts with burning/lit
magnesium
3Mg(s) + N2(g) → Mg3N2 (s)
magnesium nitride
Ionic compound
Mg2+ and N3- ions
Chlorine
Direct combination with
most metals
2Fe(s) + 3Cl2(g) → 2FeCl3 (s)
iron (III) chloride
Ionic compound
With the metal in its highest oxidation
state (3+)
Chemical Properties of Non-metal
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Reaction with Oxygen
Non-metals react with oxygen to form covalently bonded oxides which
shows mainly acidic properties. A few non-metal oxides are neutral.
The reactions of carbon and sulfur with oxygen
Element
Reaction with Oxygen
Equation
Description of the oxide
Carbon
Heated in a limited
supply of oxygen
2C (s) + O2(g) → 2CO
Carbon monoxide
A neutral oxide; toxic; combines irreversibly
with haemoglobin, reduces the capability
of haemoglobin to pick up oxygen
Heated in excess
oxygen
C (s) + O2(g) → CO2(g)
Carbon dioxide
An acidic oxide; dissolves in water forming
carbonic acid. A by-product of
fermentation.
Heated in air
S (s) + O2(g) → SO2(g)
Sulphur dioxide
An acidic oxide with a choking smell which
functions as both an oxidizing and
reducing agent. It dissolves in water to
form sulphurous acid
2SO2 (g) + O2(g) ↔ 2SO3(g)
Sulphur trioxide
The acid anhydride of sulphuric acid.
Sulphur
Reaction with Oxygen
Non-metals react with oxygen to form covalently bonded oxides which
shows mainly acidic properties. A few non-metal oxides are neutral.
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The reactions of gaseous non-metals with oxygen
Element
Reaction with Oxygen
Equation
Description of the oxide
Chlorine
When chlorine reacts with
oxygen, the oxides formed are
highly unstable (explosive)
2Cl 2(g) + O2(g) → 2Cl2O(g)
Cl 2(g) + 2O2(g) → 2ClO2(g)
• Cl2O is a orange gas.
• ClO is a yellow gas.
• Cl2O6 is a red liquid
• Cl2O7 is a colourless liquid
All of the oxides are acidic and react with
alkalis to form salts.
Nitrogen
In lightening storm
N2(g) + O2(g) → 2NO(g)
Nitrogen (II) oxide
A neutral oxide; colourless gas that combines
instantly with the oxygen in the to form the
brown gas nitrogen dioxide.
2NO2(g) + O2(g) → 2NO2(g)
nitrogen (IV) oxide
A mixed acid anhydride; reacts with water to
form nitrous acid and nitric acid.
2H2(g) + O2(g) → 2H2O(l)
water
An neutral oxide; colorless liquid
Hydrogen
When ignited
Chemical Properties of Non-metal
Oxidizing and Reducing Properties
Non-metals (carbon and sulphur))can undergo both oxidation and reduction.
Carbon and sulphur reacts with oxygen to form non-metal oxides in which the element exist
in a higher oxidation state.
These reactions shows that carbon and sulphur has reducing properties (meaning in a
reaction they become oxidized).
2C0 + O20 → 2C+2O2C0 + O20 → C+4O22
The reducing properties of carbon and sulphur are shown in their reactions with
oxidizing acids.
S(s) + 2H2 SO4(aq) → 3SO2 (g) + 2H2O (l)
3S(s) + 4HNO3(aq) → 3SO2 (g) + 4NO(g) + 2H2O(l)
C(s) + 2H2 SO4(aq) → CO2(g) + 2SO2 (g) + 2H2O (l)
C(s) + 4HNO3(aq) → CO2 (g) + 4NO(g) + 2H2O(l)
Carbon is also used to reduce some metal oxides (ores) to corresponding metals
ZnO (s) + C(s) → Zn (s) + CO(g)
Non-metals that show reducing properties usually have lower electro-negativities
than those that showing oxidizing properties.
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Oxidizing and Reducing property of nonmetals eg. Phosphorus
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Chemical Properties of Non-metal
Why do sulphur and carbon show reducing properties.
Non-metals are, typically, electronegative elements and they tend to
accept electrons from metals to form anions. When this happens, the nonmetals behave as oxidizing agents (oxidizing agents accept electrons –
reduction)
When non-metals react with each other by sharing electrons, the more
electronegative non-metal behaves as the oxidizing agent, and the less
electronegative non-metal is forced to behave as the reducing agent.
When non-metals react with more powerful oxidizing agents such as
concentrated nitric and sulphuric acids (being reduced/ or gain electrons),
the show reducing properties (reducing agents who become oxidized).
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Chemical Properties of Non-metal
Note!!!
1. Non-metals do not react with DILUTE ACIDS.
2. Non-metals do not react with WATER.
Practice Exercise
Indicate which non-metal is the oxidizing agent and which is the
reducing agent in each of the following question.
1.
C(s) + 2S(s) → CS2 (l)
2.
H2 (g) + S(s) → H2S (g)
3.
H2 (g) + Cl2 (g) → 2HCl (g)
4.
N2 (g) + 3H2 (g) → 2NH3 (g)
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Reactivity of the Non-metals
The reactivity of non-metals are
linked to their electronegativity.
Remember, electronegativity
increases from the left to the
right of the periodic table.
The greater the
electronegativity of the nonmetal the more reactive it is.
Electronegativity depends on
the size of the atom (its atomic
radius) and nuclear charge.
Small atoms have a higher
nuclear charge are highly
electronegative.
Electronegativity- Is defined as a measure
of the ability of an atom in a molecule to
draw bonding electrons to itself.
Reactivity series of non-metals
Increasing reactivity
Sulfur
Iodine
Increasing tendency to
gain electrons
Increasing power as
oxidizing agents
Oxygen, Bromine
Chlorine
Atomic Radius
- An atom gets larger as the number of electronic shells
increase; therefore the radius of atoms increases as you go
down a certain group in the periodic table of elements.
- The size of an atom will decrease as you move from left to the
right of a certain period
Fluorine
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Uses of Non-metals
Solid non-metals
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Uses
Carbon, as graphite
Lubricant, also used as the ‘lead’ in pencils
Carbon, as diamond
Used for drill bits and gemstones
Sulfur
Production of chemicals, e.g. sulphuric acid, which is
widely used in the manufacture of fertilizers and detergents
Components of matches and gunpowder
Sulphur drugs
Treatment for pulp and paper
Vulcanising rubber
Uses of Non-metals
Solid non-metals
Silicon
Uses
Used in electronic devices, such as calculators,
transitors and microcomputers
Silica, as sand, is used in the manufacturing of
glass; silicates in clay are used in the brick and
cement industry
Phosphorus
Used to make flares and fireworks; red
phosphorus is used on the striking surface of
safety matches
Phosphates are used in fertilisers and pesticides,
cleaning agents and water softeners
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Uses of Non-metals
Gaseous non-metals
Uses
Chlorine
Disinfection of water, bleaches cotton and paper
Manufacture of polychloroethene
Nitrogen
In handling of explosive mixtures, to anneal metals at
high temperatures
Flush out boilers and pipes during non-use periods
Protecting foods from spoilage
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Uses of Non-metals
Non-metals are used to:
1.
make insecticides
2.
strengthening of plastics with fibre
3.
make jewellery
4.
in tyre manufacture
5.
make matches
6.
make phosphate and other fertilisers (NPK)
7.
make bleaches
8.
make glass
9.
make ceramics
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All are electronegative elements:
decreasing order of
electronegativity is O>N, Cl, C,
S>H. Reactivity decrease in the
same direction.
Summary
Occur naturally either in free state (e.g.
N2, O2) or combined (e.g. chlorides,
oxides).
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Non-metals
Metals, to form ionic
compounds (except
sulfur)
Shows a variety
of uses
Usually reacts with acids,
except carbon doesn’t
react with conc. H2SO4
and carbon and sulfur
don’t react with HNO3
Show
Allotropy, except
Si
exist mainly as
Solids such as C, S, P
and Si
Some have
Giant
molecular
structures
(e.g. C, Si)
High melting
and boiling
points
React with:
Gases such
as H2, N2,
O2, Cl2
All have
Simple molecular
structures (e.g S, P,
Cl2, O2, H2, N2)
Have low melting and boiling
points, but the gases have
lower melting and boiling
points than the solids.
None metals, to form
covalent compounds
Oxygen, to form mainly
acidic oxides such as CO2,
SO2, SO3, SiO3, NO2, PO3,
P2O3, Cl2O, except CO, NO,
N2O and H2O which are
neutral
Practice Questions
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1. Using carbon and sulfur as examples, discuss what is meant by the
term allotropy
2. Write equations to show how sulfuric acid reacts with
a.
A metal of your choice
b.
A non-metal of your choice
c.
A based of your choice
3. Non-metallic oxides are usually acidic or neutral
a.
Give two examples of non-metallic oxides that are acidic
b.
Shows by means of equations how each of the oxides from part (a) react with
water and NaOH,
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