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The noble gases show extremely low chemical reactivity; consequently, only a few hundred noble gas compounds have been formed. Neutral compounds in which helium and neon are involved in chemical bonds have not been formed (although some helium-containing ions exist and there is some theoretical evidence for a few neutral helium-containing ones ...
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.
The noble gases (helium, neon, argon, krypton, xenon and radon) were previously known as 'inert gases' because of their perceived lack of participation in any chemical reactions. The reason for this is that their outermost electron shells (valence shells) are completely filled, so that they have little tendency to gain or lose electrons.
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 ...
It is one of the densest gases at room temperature (a few are denser, e.g. CF 3 (CF 2) 2 CF 3 and WF 6) and is the densest of the noble gases. Although colorless at standard temperature and pressure, when cooled below its freezing point of 202 K (−71 °C; −96 °F), it emits a brilliant radioluminescence that turns from yellow to orange-red ...
A chemical element is a chemical substance whose atoms all have the same number of protons.The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8, meaning each oxygen atom has 8 protons in its nucleus.
Oxygen (1s 2 2s 2 2p 4), fluorine (1s 2 2s 2 2p 5), and neon (1s 2 2s 2 2p 6) then complete the already singly filled 2p orbitals; the last of these fills the second shell completely. [ 39 ] [ 58 ] Starting from element 11, sodium , the second shell is full, making the second shell a core shell for this and all heavier elements.
A period 2 element is one of the chemical elements in the second row (or period) of the periodic table of the chemical elements.The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases; a new row is started when chemical behavior begins to repeat, creating columns of elements with similar properties.