When can a molecule form an expanded octet?

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.

Which Lewis structure uses an expanded octet?

SI6andPF5 are examples of expanded octets since they have more than 8 valence electrons.

How do you know when to obey an octet rule?

Some elements, most notably nitrogen, can form compounds that do not obey the octet rule. One class of such compounds are those that have an odd number of electrons. As the octet rule requires eight electrons around each atom, a molecule with an odd number of electrons must disobey the octet rule.

Which are the exceptions of the Lewis octet rule?

Sulfur, phosphorus, silicon, and chlorine are common examples of elements that form an expanded octet. Phosphorus pentachloride (PCl5) and sulfur hexafluoride (SF6) are examples of molecules that deviate from the octet rule by having more than 8 electrons around the central atom.

Can I have an expanded octet?

To have an expanded octet (more than 8 electrons) you need more than 4 orbitals. This means that you need to start using d-orbitals, and those are only available for atoms in the third period or below (So atoms in the third period or greater can have expanded octets.

What is expanded octet rule?

Main group elements that form more bonds than would be predicted by the octet rule are called hypervalent compounds, and have what is known as an ‘expanded octet,’ meaning that there are more than eight electrons around one atom.

How does expanded octet work?

Expanded octet occurs when an atom is able to have more than 8 valence electrons. For example, in SO₃, the sulfur atom forms 6 covalent bonds, hence it has 12 valence electrons.

How do you use octet rule?

There are two ways in which atoms can satisfy the octet rule. One way is by sharing their valence electrons with other atoms. The second way is by transferring valence electrons from one atom to another.

What is an expanded octet?

Expanded octet (hypervalent): A valence shell electron count that exceeds eight electrons. In phosphate ion (PO43-), each oxygen has a full octet (eight valence electrons), whereas phosphorus has an expanded octet (ten valence electrons).

What elements Cannot have an expanded octet?

These elements include hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine and neon. Elements that cannot have an expanded octet are: hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine and neon.

What are the Lewis formulas and octet rule?

Lewis formulas and octet rule. First. , let’s see what Lewis structure is. Lewis structure, also called electron-dot structure, is a structural formula in which electrons are represented by dots; two dots between two atoms represent a covalent bond. It was named from Gilbert Newton Lewis, who introduced it in 1916.

What are the exceptions to the octet rule?

Another exception to the octet rule is that the central atoms of certain molecules may have more than eight (octet) valence electrons (expanded octet). This usually happens when the central atom has more than four atoms bonded to it.

What is the octet rule in carbon dioxide?

The octet rule can be observed in the bonding between the carbon and oxygen atoms in a carbon dioxide molecule, as illustrated via a Lewis dot structure below. The shared electrons fulfil the valency requirements of both the bonded atoms.

How many electrons are needed to form an octet?

In order to obtain a stable octet, the two oxygen atoms share a total of four electrons via a double bond. Since ‘1p’ subshells do not exist, some elements find stability in 1s 2 configurations. On the other hand, some elements exhibit hypervalency and have the ability to form hypervalent molecules.