Second comes right after first, and helium is in second place only to hydrogen in a number of ways. It is the second lightest element, the second most abundant element, and is also the second element in the periodic table of the elements. It is, however, the first of the highly stable and unreactive noble gases (get details on noble gase properties) on the list. Indeed, it is the least reactive of them, and thus all of the elements. It also comes first in terms of having the lowest boiling point and the lowest melting point of the elements.
Helium has been created through two main sources in the universe. It was one of the few elements to emerge from the Big Bang. In our present universe by far the main source of new helium is inside stars where it is produced as a result of the fusion of hydrogen atoms deep inside the stellar furnace.
Helium in its standard form has two protons and two neutrons in its nucleus, orbited by two electrons. However, there is also a stable isotope of helium, called Helium-3, which contains an extra neutron. Helium-4 in its two liquid states is of importance to those studying quantum mechanical effects such as superfluidity and also to those studying extremely low temperatures, near to absolute zero.
Helium exists in a variety of forms of matter as a gas, a plasma, a liquid, or in the solid atomic state. In its gaseous form it is monatomic and inert. It exists rarely as a solid or a liquid, and only then under extreme pressure.
Helium is mainly found in the plasma state of matter, where the protons and electrons are not bound. This makes the matter highly electrically conductive making them very susceptible to magnetic and electrical fields. Together with hydrogen ions, helium ions are present in the solar wind, which gives rise the beautiful phenomenon known as the aurora, through interaction with the Earth’s magnetosphere.
Helium is very rare on Earth, existing only as a result of the radioactive alpha decay that can occur in far heavier elements. Alpha particles are, in fact, nuclei of helium. Helium has a variety of uses on Earth though, including everything from cryogenics to inflating balloons and airships.