WEIGHT. It's about an eighth of the density of air. Hydrogen is about a sixteenth density of air. So it will float in the air and will even float upwards.Hydrogen WOULD be a better gas as it would give slightly more lift than helium because it's lighter. The problem is hydrogen is explosive and if you have children running around with balloons that COULD catch fire and blow up in their faces, it may have some health and safety implications. The atmosphere of Earth is the layer of gases, commonly known as air, retained by Earth's gravity, surrounding the planet Earth and forming its planetary atmosphere. NitrogenIt is the chemical element with the SYMBOL N and atomic number 7. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772. Symbol: NAtomic mass: 14.0067 uAtomic number: 7Electron configuration: [He] 2s22p3HydrogenIt is the chemical element with the symbol H and atomic number 1. With a standard atomic weight of 1.008, hydrogen is the lightest element in the periodic table. Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all baryonic mass. Symbol: HAtomic mass: 1.00784 uAtomic number: 1Electron configuration: 1s1HeliumIt is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements. Symbol: HeAtomic mass: 4.002602 uAtomic number: 2Electron configuration: 1s2