What 3 elements can break the octet rule?
There are three violations to the octet rule: odd-electron molecules, electron-deficient molecules, and expanded valence shell molecules.
Which element(s) does not follow the octet rule? *The two elements that most commonly fail to complete an octet are boron and aluminum, both of which readily form compounds in which they have six valence electrons, rather than the usual eight predicted by the octet rule.
The two elements that most commonly fail to complete an octet are boron and aluminium; they both readily form compounds in which they have six valence electrons, rather than the usual eight predicted by the octet rule.
Since the first shell can only accommodate two electrons, elements such as lithium, helium, and hydrogen obey the duet rule instead of the octet rule.
Hydrogen, beryllium, and boron have too few electrons to form an octet. Hydrogen has only one valence electron and only one place to form a bond with another atom. Beryllium has only two valence atoms, and can form only electron pair bonds in two locations.
Helium has two electrons. Its electronic configuration is 1s2. So it does not have complete octet.
This usually occurs in compounds containing Be or B. Elements in the third period and below can accommodate more than an octet of electrons. Although elements such as Si, P, S, Cl, Br, and I obey the octet rule in many cases, under other circumstances they form more bonds than the rule allows. Free Radicals.
There are three violations to the octet rule: odd-electron molecules, electron-deficient molecules, and expanded valence shell molecules.
Hydrogen, beryllium, and boron have too few electrons to form an octet. Hydrogen has only one valence electron and only one place to form a bond with another atom. Beryllium has only two valence atoms, and can form only electron pair bonds in two locations.
Exception 3: Expanded Valence Shells
Hence, the third period elements occasionally exceed the octet rule by using their empty d orbitals to accommodate additional electrons.
When can an element break the octet rule?
An atom like phosphorus or sulfur which has more than an octet is said to have expanded its valence shell. This can only occur when the valence shell has enough orbitals to accommodate the extra electrons. For example, in the case of phosphorus, the valence shell has a principal quantum number n = 3.