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. More hydrogen facts.
- Liquid nitrogen boils at 77 kelvin (−196 °C, −321 °F). More nitrogen facts.
- Around 1% of the sun’s mass is oxygen. More oxygen facts.
- Helium is lighter than the air around us so it floats, that’s why it is perfect for the balloons you get at parties. More helium facts.
- Carbon comes in a number of different forms (allotropes), these include diamond, graphite and impure forms such as coal. More carbon facts, diamond facts, and coal facts.
- Under normal conditions, oil and water do not mix. More oil facts.
- Although it is still debated, it is largely recognized that the word ‘chemistry’ comes from an Egyptian word meaning ‘earth’.
- 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.
- Things invisible to the human eye can often be seen under UV light, which comes in handy for both scientists and detectives.
- Humans breathe out carbon dioxide (CO2). Using energy from sunlight, plants convert carbon dioxide into food during a process called photosynthesis.
- Chemical reactions occur all the time, including through everyday activities such as cooking. Try adding an acid such as vinegar to a base such as baking soda and see what happens!
- 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.
- 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.
- 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.)