An oxygen atom is a basic unit of matter that makes up the element oxygen, which is essential for life on Earth. It consists of eight protons in its nucleus, surrounded by eight electrons that orbit around it. The number of protons defines the element, making oxygen unique among other elements. Oxygen is represented by the chemical symbol O and has an atomic number of 8. It is a colorless, odorless gas at room temperature and is vital for processes like respiration in animals and photosynthesis in plants. Oxygen is also a key component of water, which is crucial for all known forms of life.