An allotrope is a variant form of an element with the same chemical composition but different molecular structure and properties. The document discusses several common allotropes including carbon (diamond, graphite), phosphorus (white, red), oxygen (O2, O3), sulfur (rhombic, monoclinic), boron (amorphous, crystalline), and silicon (amorphous, crystalline). Allotropes have substantial differences in their physical properties due to variations in atomic bonding arrangements.

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