1. Allotropes
By

Sakshi Shetty

Manasvee Saraf

Sneha Shastri

2. What is an Allotrope?
An allotrope
• is a variant of a substance consisting of only one type of
atom.
• a new molecular configuration, with new physical
properties.
Allotropes of a given substance will often have substantial
differences between each other. For example, one
allotrope of carbon, fullerene, is many times stronger and
lighter than steel.

3. What is an Allotrope?
• Allotropes are different forms
of the same element.
• Different bonding
arrangements between atoms
result in different structures
with different chemical and
physical properties.
• Allotropes occur only with
certain elements, in Groups 13
through 16 in the Periodic
Table. This distribution of
allotropic elements is
illustrated in Figure 1.
Figure 1

4. Elements and Their Allotropes
The following slides are about a few common elements
and their allotropes... You will find allotropes of

Carbon

Phosphorus

Oxygen

Sulphur

Boron

Silicon

5. Allotropes of Carbon
 A striking example of differing physical
properties among allotropes is the case
of carbon. Solid carbon exists in two
allotropic forms: diamond and graphite.
• Diamond is the hardest naturally occurring
substance and has the highest melting point
(more than 6,335°F [3,502°C]) of any
element.
• In contrast, graphite is a very soft material,
the substance from which the "lead" in lead
pencils is made.
 The 8 Allotropes of Carbon are: a)
Diamond, b) Graphite, c)Lonsdaleite, d)
Buckminsterfullerene, e) C540, f)C70,
g)Amorphous, h) Carbon Nanotube

6. Allotropes of Phosphorus
White phosphorus -
crystalline solid P4
Red phosphorus -
polymeric solid
Scarlet phosphorus
Violet phosphorus
Black phosphorus
Diphosphorus

7. Allotropes of Oxygen
A. Dioxygen- O2
B. Ozone- O3
C. Tetraoxygen- O4
D. Octaoxygen- O8
A
B C D

8. Allotropes of Sulphur

Plastic (Amorphous)
Sulphur - polymeric solid

Rhombic Sulphur - large
crystals composed of S8
molecules

Monoclinic Sulphur - fine
needle-like crystals

Other ring molecules such
as S7 and S12
Rhombic
Sulphur
Monoclinic
Sulphur

9. Allotropes of Boron

Amorphous Boron -
brown powder

Crystalline Boron -
black, hard, and a
weak conductor at
room temperature.
Crystalline Boron
Amorphous
Boron

10. Allotropes of Silicon

Amorphous Silicon -
brown powder

Crystalline Silicon -
has a metallic luster
and a grayish color.
Amorphous
Silicon
Crystalline
Silicon