Argon has 18 protons and 18 electrons. Its atomic number is 18, and its mass number is 40 grams per mole. Argon is a noble gas and is found in group 18 on the periodic table.
Argon was first discovered in 1894 by Lord Rayleigh and Sir William Ramsay. It is the third most common gas in Earth’s atmosphere, and it is not harmful to the environment or ecological processes. The gas is harmful to humans if inhaled in large doses. Argon can be absorbed into the human body, through inhalation, and cause dizziness and headaches. In extreme cases, argon inhalation can lead to suffocation.