Carbon and Its Compounds – CHEM 2.6 (Secondary Level Chemistry) – Essential Topic Summary and Concept Guide

CARBON
AND SOME OF ITS COMPOUNDS

Table of Contents
Carbon and its Allotropes ................................ Organizer 2-
Diamond and Graphite ................................
Fullerenes and Amorphous Carbon ................................
Chemical Properties of Carbon ................................
Carbon (IV) oxide (CO2) ................................ 5-
Preparation of Carbon (IV) oxide ................................
Properties of carbon (IV) oxide ................................
Uses of Carbon (IV) oxide gas ................................
Carbon (II) Oxide ................................................................ 8-
Preparation of carbon (II) oxide ................................
Properties of carbon (II) oxide ................................
Other Sources of Carbon (II) oxide ................................
Uses of carbon (II) oxide. ................................
Checkpoint I ................................................................
Carbonates................................................................ -
Reaction with dilute acids ................................
Action of Heat ................................................................
Large scale production of Na2CO3 ................................
Effects of Carbon (IV) and Carbon (II) oxides on
the Environment ................................................................ -
Checkpoint (II) ................................................................
(20 Lessons)

Objectives
By the end of this chapter, the learner should be able to:
(a) Define the terms allotropy and allotropes.
(b) State and explain some physical and chemical properties of carbon.
(c) Describe the laboratory preparation of carbon (IV) and carbon (II) oxides
(d) State and explain the physical and chemical properties of carbon (IV) and carbon (II) oxide
(e) State the uses of carbon, carbon (IV) and carbon (II) oxides.
(f) Describe the chemical properties of carbonates and hydrogen carbonates.
(g) Describe the extraction and manufacture of sodium carbonate.
(h) State the effects of carbon (IV) and carbon (II) oxides on the environment.

, - 2 - INORGANIC CHEMISTRY




CARBON
AND SOME OF ITS COMPOUNDS

Carbon is the first element in group (IV) of the periodic table. It has an electron arrangement

of 2.4. It forms covalent bonds in most of its compounds.

It occurs in the pure state as diamond and graphite, and in the impure state as amorphous
carbon. It also occurs in the combined state in compounds such as carbonates, mineral oils,

organic matter, and carbon (IV) oxide.



Carbon and its Allotropes
Allotropy is the existence of an element in more than one form, in the same physical state.
The different forms are called allotropes.

Carbon has two naturally occurring allotropes, diamond and graphite.

Carbon can be manipulated using energy such as laser beams to form other allotropes known
as fullerenes or ‘buckyballs’.

Diamond
This is one of the stable allotropes of carbon. It is a colourless, transparent shiny crystalline
solid.

In diamond, carbon uses all the four valence electrons to form covalent bonds. Since it uses

all the four electrons in the outermost energy level for bonding, it does NOT conduct both

electricity and heat.

Diamond has a density of 3.51 g/cm3. The high density is due to continuous close packing
of carbon atoms.

Diamond has a high meltinghighmeltingpoint is(3700ºC)duetothestrong. The covalent bonds.



Diamond is one of the hardest naturally occurring substances. The hardness is due to the
uniformity of covalent bonds between the atoms throughout the structure.

Diamond has a giant atomic structure in which each carbon atom is bonded to four other

,carbon atoms arranged in a regular tetrahedron shape. The whole structure of diamond

extends in all directions forming a rigid mass of atoms.

Diamond is found in some parts of India, South Africa and in Tanzania where it is mined. It is

used as a jewel because of its shiny appearance when polished. It is used in glass cutters

and drill bits because of its hardness.

, CHEMISTRY OF CARBON - 3 -




Graphite
This is another stable allotrope of carbon. It is a black, soft, slippery crystalline solid.

Graphite is made up of hexagonally arranged carbon atoms bonded together in layers
where each atom is bonded to three carbon atoms. The layers are held together by van der

Waals forces.

Graphite has a density of 2.3g/cm3. The low density is due to the spaces between the layers.
It is soft and slippery because the layers in the structure can slide over each other due to
the weak van der Waals forces.

In graphite, each carbon atom uses only three electrons in the outer energy level to form

covalent bonds with other carbon atoms. One electron in the outer energy level of each atom

is not used in bonding. It is delocalised hence graphite conducts heat and electricity.

Both melting point (3500ºC) and boilinghighbecause pointofthe (4 strong covalent bonds between the
atoms in its layers. Graphite has a giant atomic

structure in which layers are held together by van der Waals forces.

The high melting point and its slippery nature makes graphite a good lubricant in moving
machine parts where a lot of heat is produced.

The high melting point also makes graphite useful in making moulds for casting metals. It
has delocalised electrons within its structure hence is used as an electrode.

Graphite is mixed with clay to make thepencilcarbonlayers ‘leads’canslideover beca each other.
Graphite is found in South Africa, Brazil, Sweden, Germany and U.S.A.



Fullerenes
Fullerenes are synthetic allotropes of carbon. They are found in different shapes such as

spherical, tubular or elliptical. The best known fullerene is the spherical C60 molecule which
consists of hexagonally arranged carbon atoms similar to the panels of some soccer balls.



Amorphous Carbon
This is an impure form of carbon. Examples are charcoal, soot, coke and coal. They contain