What element does 'O' represent on the periodic table?

The symbol 'O' on the periodic table represents the element Oxygen. Oxygen is a vital element for life on Earth, as it is essential for respiration in most living organisms and is a key component of water (H2O). It is found in group 16 of the periodic table, also known as the chalcogens, and has an atomic number of 8.

Oxygen exists in several forms, including diatomic oxygen (O2), which is the form that is predominantly found in the atmosphere and is necessary for the survival of aerobic organisms. Its chemical reactivity and ability to form compounds with a wide variety of elements make it one of the most important elements in chemistry and biology.

The other choices are distinct elements: Osmium is denoted by the symbol 'Os', Gold is represented by 'Au', and Iron is symbolized by 'Fe', each having unique properties and applications in science and industry. This highlights the importance of knowing the symbols and their corresponding elements on the periodic table to better understand chemical reactions and the composition of matter.