Oxygen

Oxygen
Photo Credit: Theodore Gray

Symbol - O
Atomic Number: 8
Relative Mass: 16 (15.99)
Group: 16
Block: P

Oxygen is the most plentiful element of the Earth's crust. Though it only makes 21% of the atmosphere. It is a colourless and odourless gas which have two forms of itself. Oxygen either binds to two or three atoms of themselves, O2 and O3. It appeared first within the Earth's atmosphere around 2 billion years ago from the process of Photosynthesis.

Oxygen was one of those elements discovered by multiple chemists. In this case, there are three different chemists who discovered this element: Joseph Priestley - an English man, Carl Wilhelm Scheele - a Swedish man and Antoine Lavoisier - a Frenchman. All of these chemists discovered Oxygen in their own times - independent of each other. Like most chemists, they were convinced that air had at least two different types of gases. I have already mentioned this thought once before on a previous element blog post: Nitrogen (I'll cover it again). Chemists believed that there was one gas which could support combustion and another one which was always left behind afterwards.
Now, we know that air contains at least 4 gases - Nitrogen (78.1%), Oxygen (20%), Argon (0.9%) and Carbon dioxide (0.04).

This is Joseph Priestley
Photo Credit: Wikipedia

Joseph Priestley and Carl Scheele used a similar method to isolate Oxygen. The method (The way he did his experiment) was to heat a few different substances like Potassium or Mercury Oxide to gain the pure sample of the gas. The theory was based on another theory called Phlogiston theory. Phlogiston Theory is the principles of fire, saying that everything flammable will be burnt. So in this experiment, Oxygen (the thing they wanted) would disappear from the metal as they realised that it did burn. This experiment was well founded and was a popular method among chemists in the 18th century.
Joseph Priestley published his work first and therefore, he got the credit. Joseph also placed a candle along with a mouse into a closed system. The scientist noted that the candle died out and the mouse eventually died. Therefore, it was easily deduced that both the fire and animal needed Oxygen to survive. Joseph Priestley called this gas - dephlogisticated.

The name of the element comes from the French chemist - Antoine Lavoisier. Antoine used Oxygen's other tendency to form acids with other elements as the inspiration. The word Oxygen originates from two Greek words - Oxy which means acid and 'gen' comes from the word genes which means forming.

Biological Uses

• It have been used for respiration - living things needs to take in Oxygen in order to respire.

  

  A Photosynthesis Poster

  Credit: LifeHack

  Carbon dioxide is excreted (Breathed out)
• Oxygen is the waste product of photosynthesis. Photosynthesis is the process of using the sun's energy to split water into hydrogen and Oxygen. Oxygen goes back into the atmosphere while the hydrogen is bound to Carbon dioxide to create different carbohydrates. 
• Oxygen gas can dissolve in water - which is how aquatic life within rivers, ponds and oceans are possible.

Use

• The greatest use of Oxygen is in the steel industry. 
• Large quantities of Oxygen is also used within the manufacturing of nitric acid and hydrogen peroxide.
• Oxygen is used to make the chemical, epoxyethane which is used mostly as antifreeze.