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Climate Change classes 1
UQ 3 May 07 Cars and ozone
UQ 2 Mar 07 Urban air
Climate change 2007 IPCC special
UQ 1 Nov Dec 06 Particles in air
Preface
Introduction
F: Perception of air
F: Phase transitions
F: Polarity and ions
R: Particle Measurement
R: Formation of S Aerosol
A: Combustion of plants
C: Information for teachers
Special: Oct. 2006 Communication
Nr 10 Sept. 2006 Africa's emissions
Nr 9 July 06 Air traffic
Special: June 06 Climate summit
Nr 8 April 2006 Ozone & N2 cycle
Nr 7 March 2006 Climate modeling
Nr 6 Feb. 2006 acid rain
Nr 5 Jan. 2006 oceanic sulfur
Special: Nov 05 Ozzy Ozone
Nr 4 Oct. 2005 light/satellites
Special: Sept 05 Cyclones
Nr 3 Sept. 2005 methane/energy
Special: July 05 Greenhouse Earth
Nr 2 June 2005 forest/aerosols
No 1 May 2005 vegetation/CO2
     
Fundamentals

Fundamentals B2: Polarity and Ions

 Bonds in salts

Water forms easier a liquid or a solid since the smallest particles of water attract each other. We say: Water molecules are polar. They behave like little magnets, which stick to each other.
  

For salts it is even easier than for water to turn into a solid state. Their smallest particles, the positive and negative ions, attract each other heavily.

Just ask your parents for an old pot, which is not needed anymore. Put it on the stove and give a teaspoon of dry table salt into it. Switch the stove on and choose the highest grade. What happens?
  
 

hydrogen bonds

1. Polar hydrogen bonds in liquid water; image: Elmar Uherek

ionic crystel model

2. Ionic crystal of a salt, as for example given in table salt

Salzkristall

3. A salt crystal in reality. The order in the ion grid is the reason for the even surface.

As you see the enormous heat does not affect the salt. Salts dilute in water but in a dry environment they form stable crystals. This is because their smallest particles, the ions, are strongly attached to each other.
 

Ammoniumsulfat Partikel

4. Ammonia sulphate strongly enlarged
Source: PSI

 Salts in the air

We can imagine that the ions in a salt crystal have strong positive and negative charges, which are hard to separate from each other. They attract each other like very strong magnets. If salts are brought into the air or if they are formed in air thanks to a chemical reaction they do not evaporate anymore.
  

They form floating salt particles that can attract the humidity of the air. With increasing size they tend to sink to the ground. In order to produce very fine particles a chemical reaction is used, which is also an important source of particles in nature: Sulfuric acid and ammonia form ammonium sulfate salts.
 

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last updated 16.01.2007 | © ACCENT - Atmospheric Composition Change 2013