hydrogen
Not only that, but it's one of lightest, or possibly the lightest, gas in the world. I'm a nerd, so you can trust me.
Many people might think the answer to this question would be an atom, but not in life. The structures go like this from largest to smallest: Ecosystem, Community, Organism, Organ system, Organ, Tissue, Cell.
The smallest atom is hydrogen.
An electron is a sub-atomic particle, not an atom. But it is electrically charged (it has a charge of minus one). The simplest atom, the hydrogen one isotope, has just one proton and one electron. An electron is a part of an atom. Every atom is composed of protons and electrons. Usually there are also neutrons. Protons are positively charged +1 and electrons are charged -1. Neutrons are neutral. When the number of protons and electrons are equal the atom is neutral. When an atom has an unequal number of protons and electrons it is charged either - or +. More electrons make it - and more protons make it +. In both cases the atom is called an ion.
In our known universe, hydrogen then helium. But this may change with further exploration.
Hydrogen is the lightest element. The isotope protium is the lightest kind of hydrogen atom.
Hydrogen is the lightest and most common atom in the universe. It has the symbol H and an atomic number of 1.
An atom with a nucleus that has no neutrons is hydrogen-1, which consists of one proton and no neutrons. It is the simplest and lightest element on the periodic table.
Hydrogen is the lightest (it is a gas) and most abundant element in the Universe. A hydrogen atom consists of a single proton and a single electron, making it the simplest atom in the Universe.
electrons
An atom is composed of three main particles, the proton, electron and neutron. The electron is the lightest among the three.
The lightest particle in the atom is the electron.
Hydrogen is the lightest chemical element; the chemical symbol is H.
The lightest and smallest atom is hydrogen. It has a single proton and a single electron. There are some other isotopes of hydrogen that have one or more neutrons. Although those isotopes are naturally occurring, they are rare and for most purposes, we can ignore their existence.
The simplest organized substance known is probably elemental hydrogen, with each atom consisting of just one proton and one electron. Hydrogen is the lightest and most abundant element in the universe.
The only element that has one proton and no neutrons is a hydrogen atom.
hydrogen