Gas elements are a group of elements that exist in gaseous form at room temperature. OXYGEN (6 letters) is the most abundant gas element in the Earth's atmosphere, and is essential for human life. ARGON (5 letters) is the third most abundant gas element in the atmosphere and is used in lighting and welding. HELIUM (6 letters) is the second most abundant gas element in the universe and is used in balloons and cryogenics. NEON (4 letters) is a noble gas element that is used in NEON signs and lasers. RADON (5 letters) is a radioactive gas element that is found in soil and rocks and can be hazardous to human health.