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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.
The periodic table, also known as the periodic table of the elements, ... Hydrogen is the element with atomic number 1; helium, atomic number 2; lithium, ...
The definitive visualisation of all 118 elements is the periodic table of the elements, ... Helium [l] 18 1 s-block 4.0026: 0.000 1785
In 1902, having accepted the evidence for the elements helium and argon, Dmitri Mendeleev included these noble gases as group 0 in his arrangement of the elements, which would later become the periodic table. [11] Ramsay continued his search for these gases using the method of fractional distillation to separate liquid air into several components.
Helium (He) is a colorless, odorless, tasteless, non-toxic, inert monatomic chemical element that heads the noble gas series in the periodic table and whose atomic number is 2. [32] Its boiling and melting points are the lowest among the elements and it exists only as a gas except in extreme conditions. [33]
In chemistry and atomic physics, the main group is the group of elements (sometimes called the representative elements) whose lightest members are represented by helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, and fluorine as arranged in the periodic table of the elements.
He, 2, helium : 1s 2 Ne, 10, neon : ... The construction of the periodic table ignores these irregularities and is based on ideal electron configurations. [2]
The most common values of atomicity for the first 30 elements in the periodic table are as follows: ... Atomicity 1 Hydrogen (H) 2 2 Helium (He) 1 3 Lithium (Li) 1 4 ...