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Neon is a chemical element; it has symbol Ne and atomic number 10. It is the second noble gas in the periodic table. [13] Neon is a colorless, odorless, inert monatomic gas under standard conditions, with approximately two-thirds the density of air. Neon was discovered in 1898 alongside krypton and xenon, identified as one of the three ...
The reason is that there is no primordial helium in the atmosphere; due to the small mass of the atom, helium cannot be retained by the Earth's gravitational field. [71] Helium on Earth comes from the alpha decay of heavy elements such as uranium and thorium found in the Earth's crust, and tends to accumulate in natural gas deposits. [71]
The abundances of the naturally occurring isotopes of neon. Neon (10 Ne) possesses three stable isotopes: 20 Ne, 21 Ne, and 22 Ne. In addition, 17 radioactive isotopes have been discovered, ranging from 15 Ne to 34 Ne, all short-lived. The longest-lived is 24 Ne with a half-life of 3.38(2) min. All others are under a minute, most under a second.
Trace gas. Trace gases are gases that are present in small amounts within an environment such as a planet 's atmosphere. Trace gases in Earth's atmosphere are gases other than nitrogen (78.1%), oxygen (20.9%), and argon (0.934%) which, in combination, make up 99.934% of its atmosphere (not including water vapor).
Helium. hexagonal close-packed (hcp) Helium (from Greek: ἥλιος, romanized: helios, lit. 'sun') is a chemical element; it has symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table.
Abundance (atom fraction) of the chemical elements in Earth's upper continental crust as a function of atomic number; [5] siderophiles shown in yellow. Graphs of abundance against atomic number can reveal patterns relating abundance to stellar nucleosynthesis and geochemistry. The alternation of abundance between even and odd atomic number is ...
e. In the context of the periodic table a nonmetal is a chemical element that mostly lacks distinctive metallic properties. They range from colorless gases like hydrogen to shiny crystals like iodine. Physically, they are usually lighter (less dense) than elements that form metals and are often poor conductors of heat and electricity.
Neon lights are a type of cold cathode gas-discharge light. A neon tube is a sealed glass tube with a metal electrode at each end, filled with one of a number of gases at low pressure. A high potential of several thousand volts applied to the electrodes ionizes the gas in the tube, causing it to emit colored light.