Chemical element with the symbol He and atomic number 2.- Helium
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Fifth planet from the Sun and the largest in the Solar System.
Jupiter is primarily composed of hydrogen, but helium constitutes one-quarter of its mass and one-tenth of its volume.
Helium-4 is a stable isotope of the element helium.
Star at the center of the Solar System.
Roughly three-quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.
One of the four fundamental states of matter .
When grouped together with the monatomic noble gases – helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) – these gases are referred to as "elemental gases".
Dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies.
Several elements, including helium, thallium, and caesium, were discovered by spectroscopic means.
Tabular display of the chemical elements.
Hydrogen is the element with atomic number 1; helium, atomic number 2; lithium, atomic number 3; and so on.
Measure of the occurrence of the chemical elements relative to all other elements in a given environment.
As another example, looking at the mass-fraction abundance of hydrogen and helium in both the Universe as a whole and in the atmospheres of gas-giant planets such as Jupiter, it is 74% for hydrogen and 23–25% for helium; while the (atomic) mole-fraction for hydrogen is 92%, and for helium is 8%, in these environments.
A balloon is a flexible bag that can be inflated with a gas, such as helium, hydrogen, nitrous oxide, oxygen, and air.
Prevailing cosmological model explaining the existence of the observable universe from the earliest known periods through its subsequent large-scale evolution.
Giant clouds of these primordial elements—mostly hydrogen, with some helium and lithium—later coalesced through gravity, forming early stars and galaxies, the descendants of which are visible today.
A chemical element refers to all aspects of the species of atoms that have a certain number of protons in their nuclei, including the pure substance consisting only of that species.
The lightest chemical elements are hydrogen and helium, both created by Big Bang nucleosynthesis during the first 20 minutes of the universe in a ratio of around 3:1 by mass (or 12:1 by number of atoms), along with tiny traces of the next two elements, lithium and beryllium.