What is an expanded octet in chemistry?
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).
When can you expand an octet?
Expansion of octet is possible only from Period 3 elements onwards, due to the presence of low-lying empty d orbitals that can accommodate the extra electrons. Octet expansion is when deviation from octet rule occurs, i.e. atoms hold more than 8 valence electrons which is considered the stable electronic configuration.
Which elements Cannot have an expanded octet?
Elements in the first and second periods of the periodic table cannot have an expanded octet. These elements include hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine and neon.
What is the Epicentre of octet rule?
The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell. When atoms have fewer than eight electrons, they tend to react and form more stable compounds.
Can B expand its 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.
Why can elements have expanded octets?
Species with Expanded Octets 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.
Is co2 an expanded octet?
The Octet Rule and Its Exceptions Valence electrons can be counted using a Lewis electron dot diagram. In carbon dioxide, for example, each oxygen shares four electrons with the central carbon. These four electrons are counted in both the carbon octet and the oxygen octet because they are shared.
Can oxygen have an expanded octet?
Atoms with an expanded octet Phosphorous often has 5 orbitals (10 electrons) and sulfur often has 6 orbitals (12 electrons) because they are in the third period, but nitrogen and oxygen can never have expanded octets because they are in the second period and there is not such thing as a 2d orbital.
What elements can exceed the octet rule?
– molecules with an odd number of electrons: NO (nitric oxide) – molecules with less than 8 electrons around an atom: BH3 (borane) – molecules with more than 8 electrons around an atom: SF6 (sulfur hexaflouride)
What violates the octet rule?
Why can an odd-electron molecule not satisfy the octet rule?
What are the three exceptions to the octet rule?
An electron or molecule which contains unpaired electrons in its outermost shell or valence shell is considered as free radical.
Which elements cannot have an expanded octet?
Phosphorous often has 5 orbitals (10 electrons) and sulfur often has 6 orbitals (12 electrons) because they are in the third period, but nitrogen and oxygen can never have expanded octets because they are in the second period and there is not such thing as a 2d orbital.