Interesting facts of chemistry.

                                                             Chemistry

1. The use of various forms of chemistry is believed to go back as long ago as the Ancient Egyptians. By 1000 BC civilizations were using more complex forms of chemistry such as using plants for medicine, extracting metal from ores, fermenting wine and making cosmetics.
2. Things invisible to the human eye can often be seen under UV light, which comes in handy for both scientists and detectives.
3. Humans breathe out carbon dioxide (CO₂). Using energy from sunlight, plantsconvert carbon dioxide into food during a process called photosynthesis.
4. Above 4 °C, water expands when heated and contracts when cooled. But between 4 °C and 0 °C it does the opposite, contracting when heated and expanding when cooled. Stronger hydrogen and oxygen bonds are formed as the water crystallizes into ice. By the time it's frozen it takes up around 9% more space.
5. Liquid nitrogen boils at 77 kelvin (−196 °C, −321 °F).
6. Carbon comes in a number of different forms (allotropes), these include diamond, graphite and impure forms such as coal.
7. Often formed under intense pressure over time, a crystal is made up of molecules or atoms that are repeated in a three dimensional repeating pattern. Quartz is a well known example of a crystal.
8. Athletes at the Olympic Games have to be careful how much coffee they drink. The caffeine in coffee is a banned substance because it can enhance performance. One or two cups are fine but they can go over the limit with more than five. (update - as of 2004 caffeine has been taken back off the WADA banned list but its use will be closely monitored to prevent future abuse by athletes
9. Helium is lighter than the air around us so it floats, that's why it is perfect for the balloons you get at parties
10. Hydrogen is the first element on the periodic table. It has an atomic number of 1. It is highly flammable and is the most common element found in our universe