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  2. Octet rule - Wikipedia

    en.wikipedia.org/wiki/Octet_rule

    The octet rule is a chemical rule of thumb that reflects the theory that main-group elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas. The rule is especially applicable to carbon, nitrogen, oxygen, and the halogens; although more generally the ...

  3. Doublet state - Wikipedia

    en.wikipedia.org/wiki/Doublet_state

    In quantum mechanics, a doublet is a composite quantum state of a system with an effective spin of 1/2, such that there are two allowed values of the spin component, −1/2 and +1/2. Quantum systems with two possible states are sometimes called two-level systems. Essentially all occurrences of doublets in nature arise from rotational symmetry ...

  4. Valence electron - Wikipedia

    en.wikipedia.org/wiki/Valence_electron

    As a general rule, a main-group element (except hydrogen or helium) tends to react to form a s 2 p 6 electron configuration. This tendency is called the octet rule, because each bonded atom has 8 valence electrons including shared electrons. Similarly, a transition metal tends to react to form a d 10 s 2 p 6 electron configuration.

  5. Linnett double-quartet theory - Wikipedia

    en.wikipedia.org/wiki/Linnett_Double-Quartet_Theory

    In the traditional Lewis view, this violates the octet rule as the five phosphorus-chlorine bonds would result in a net ten electrons around the phosphorus atom. Thus, the molecule is assumed to expand its bonding beyond the octet, a situation known as hypervalent bonding.

  6. Multiplicity (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Multiplicity_(chemistry)

    In organic chemistry, carbenes are molecules which have carbon atoms with only six electrons in their valence shells and therefore disobey the octet rule. [5] Carbenes generally split into singlet carbenes and triplet carbenes, named for their spin multiplicities.

  7. Period (periodic table) - Wikipedia

    en.wikipedia.org/wiki/Period_(periodic_table)

    The first period contains fewer elements than any other, with only two, hydrogen and helium. They therefore do not follow the octet rule, but rather a duplet rule. Chemically, helium behaves like a noble gas, and thus is taken to be part of the group 18 elements. However, in terms of its nuclear structure it belongs to the s-block, and is therefore sometimes classified as a group 2 element, or ...

  8. Electron counting - Wikipedia

    en.wikipedia.org/wiki/Electron_counting

    In chemistry, electron counting is a formalism for assigning a number of valence electrons to individual atoms in a molecule. It is used for classifying compounds and for explaining or predicting their electronic structure and bonding. [1] Many rules in chemistry rely on electron-counting: Octet rule is used with Lewis structures for main group elements, especially the lighter ones such as ...

  9. Gilbert N. Lewis - Wikipedia

    en.wikipedia.org/wiki/Gilbert_N._Lewis

    Gilbert Newton Lewis ForMemRS [1] (October 23 [2][3][4] or October 25, 1875 – March 23, 1946) [1][5][6] was an American physical chemist and a dean of the college of chemistry at University of California, Berkeley. [3][7] Lewis was best known for his discovery of the covalent bond and his concept of electron pairs; his Lewis dot structures ...