Oxygen

• Oxygen is the third most abundant element in the universe.

• It reacts with all elements except helium and neon.

• The reaction with oxygen is called oxidation.

• It has the second strongest oxidising power after fluorine.

Reactive Oxygen Species (ROS)

• During the metabolism of oxygen, many reactive molecules, ions and radicals are generated as intermediates or side products.

• These are called Reactive Oxygen Species (ROS).

• These species include superoxide anion (O2-), hydrogen peroxide (H2O2), and hydroxyl radical (•OH), which can lead to oxidative stress in cells if not regulated effectively.