-Molecular Elements -Allotropes

1
-Molecular Elements -Allotropes

• Contemporary ChemistryMrs. Coyle

2
Molecular Elements

• Elements whose atoms are bonded together and form
  a molecule.

3
Diatomic Molecules

• H2
• N2
• O2
• F2
• Cl2
• Br2
• I2

• There are 7 diatomic elements.

4
Types of Bonds in the Diatomic Molecules

• All except O2 and N2 have a single covalent bond
  joining their two atoms.
• O2 has a double bond.
• N2 has a triple bond.

5
Allotropes

• Molecules of the same element that have
  different molecular or crystalline structures.
• The properties of allotropes are different even
  though they contain the same element.

6
Allotropes of Phosphorus

• White, red, and black phosphorous, P4
• White phosphorus is extremely reactive and toxic
  (was used in destructive weapons such as napalm).
  It ignites in air.
• Red phosphorus is less reactive than white and is
  used in the strike pad of safety matches.
• Black phosphorus is the least reactive of these.

7
Allotropes of Oxygen

• Diatomic oxygen, O2 .. .. ..
• Ozone, O3 O O O .. ..

8
Ozone, O3

• Ozone can be created during lightning storms from
  O2.
• Ozone is harmful to the respiratory system and
  near the surface of the earth is considered an
  air pollutant.
• Ozone exists in the upper atmosphere and provides
  protection from the UV rays to the living beings
  on the earth. CFCs that deplete the ozone layer
  have been banned in the US.

9

• http//www.noaanews.noaa.gov/stories2006/s2624.htm

10
Allotropes of Carbon

• Diamond
• Graphite
• Bucky Balls

11
Graphite

• Used in pencils.

12
Diamond
13
Buckminsterfullerene Bucky Ball
14
(No Transcript)