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Helium is the second least reactive noble gas after neon, and thus the second least reactive of all elements. [95] It is chemically inert and monatomic in all standard conditions. Because of helium's relatively low molar (atomic) mass, its thermal conductivity , specific heat , and sound speed in the gas phase are all greater than any other gas ...
The noble gases have also been referred to as inert gases, but this label is deprecated as many noble gas compounds are now known. [6] Rare gases is another term that was used, [ 7 ] but this is also inaccurate because argon forms a fairly considerable part (0.94% by volume, 1.3% by mass) of the Earth's atmosphere due to decay of radioactive ...
For example, N 2, the diatomic form of nitrogen, is used as an inert gas in situations where using argon or another noble gas would be too expensive. Formation of multiple bonds is facilitated by their five valence electrons, as the octet rule permits a pnictogen to accept three electrons on covalent bonding.
Because of its scarcity, xenon is much more expensive than the lighter noble gases—approximate prices for the purchase of small quantities in Europe in 1999 were 10 €/L (=~€1.7/g) for xenon, 1 €/L (=~€0.27/g) for krypton, and 0.20 €/L (=~€0.22/g) for neon, [67] while the much more plentiful argon, which makes up over 1% by volume ...
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
At standard temperature and pressure, two atoms of the element bond to form N 2, a colourless and odourless diatomic gas. N 2 forms about 78% of Earth's atmosphere, making it the most abundant chemical species in air. Because of the volatility of nitrogen compounds, nitrogen is relatively rare in the solid parts of the Earth.
Two-phase detectors containing argon gas are used to detect the ionized electrons produced during the WIMP–nucleus scattering. As with most other liquefied noble gases, argon has a high scintillation light yield (about 51 photons/keV [ 39 ] ), is transparent to its own scintillation light, and is relatively easy to purify.
The two general trends in the remaining stellar-produced elements are: (1) an alternation of abundance in elements as they have even or odd atomic numbers (the Oddo–Harkins rule), and (2) a general decrease in abundance as elements become heavier. Iron is especially common because it represents the minimum energy nuclide that can be made by ...