Below are some common situations that we come across in everyday life and why they are caused by chemistry.
• Blue sky - the blue color of the sky can be explained by light being scattered through molecules that are smaller than its wavelength. Most particularly nitrogen molecules as the blue effect is most strong when light is scattered through gas particles.
• Coffee keeps us awake - as you probably already know, coffee contains a substances called caffeine, which is what keeps us awake, but why does it do this. Well, caffeine uses the same mechanisms that are present in drugs like cocaine and heroin and amphetamines, although it is a lot milder. These change the channels in the brain, which gives coffee its addictive quality.
• Love - this can also be explained through chemistry but only to a certain extent, as the matters of the heart cannot be explained. Lust is driven by pheromones, whereas the sensation of falling in love is all to do with the levels of dopamine, serotonin and other neuro chemicals in the brain. The chemistry that is involved during a long term relationship is completely different to when a relationship first sets out. This is a vast subject so for more information, use the following link: http://www.silviamar.com/Documents/love.htm.
• Crying when chopping onions - onions contain chemicals that have sulfur inside them. This is released when we chop onions as the cells are broken, and a chemical reaction takes place which converts the sulfur into a volatile compound. This is then released into the air. This compound in the air reacts with the moisture in our eyes and produces a burning sensation. To try and compensate for this, our eyes water profusely to try and wash the compound out of our eyes. Try to avoid this by chopping onions under running water.