Consider the molecule of nitrosopropane. Its Lewis structure is shown. Н Н THI C C C Н Н Н How many sigma (♂) and how many pi (π) bonds are there in the nitrosopropane molecule? 1 sigma and 11 pi bonds 11 sigma and 1 pi bonds 10 sigma and 1 pi bonds 7 sigma and 4 pi bonds 1 sigma and 10 pi bonds
Formal Charges
Formal charges have an important role in organic chemistry since this concept helps us to know whether an atom in a molecule is neutral/bears a positive or negative charge. Even if some molecules are neutral, the atoms within that molecule need not be neutral atoms.
Polarity Of Water
In simple chemical terms, polarity refers to the separation of charges in a chemical species leading into formation of two polar ends which are positively charged end and negatively charged end. Polarity in any molecule occurs due to the differences in the electronegativities of the bonded atoms. Water, as we all know has two hydrogen atoms bonded to an oxygen atom. As oxygen is more electronegative than hydrogen thus, there exists polarity in the bonds which is why water is known as a polar solvent.
Valence Bond Theory Vbt
Valence bond theory (VBT) in simple terms explains how individual atomic orbitals with an unpaired electron each, come close to each other and overlap to form a molecular orbital giving a covalent bond. It gives a quantum mechanical approach to the formation of covalent bonds with the help of wavefunctions using attractive and repulsive energies when two atoms are brought from infinity to their internuclear distance.
In the Lewis structure, the atoms are connected as follows:
- Three carbon atoms (C) are connected in a chain.
- The first carbon (C) is bonded to three hydrogen (H) atoms.
- The second carbon (C) is bonded to two hydrogen (H) atoms.
- The third carbon (C) is bonded to two hydrogen (H) atoms and a nitrogen (N) atom.
- The nitrogen (N) atom is double-bonded to an oxygen (O) atom, which also has two lone pairs of electrons.
**Question:**
How many sigma (σ) and how many pi (π) bonds are there in the nitrosopropane molecule?
**Options:**
- 1 sigma and 11 pi bonds
- 11 sigma and 1 pi bonds
- 10 sigma and 1 pi bonds
- 7 sigma and 4 pi bonds
- 1 sigma and 10 pi bonds
**Explanation:**
A **sigma bond (σ bond)** is a single covalent bond formed by the direct overlap of orbitals from two atoms, which lies along the axis connecting the two nuclei. A **pi bond (π bond)** is formed by the side-by-side overlap of two p orbitals.
For nitrosopropane:
- Each C-H bond is a sigma bond.
- Each C-C bond is a sigma bond.
- The C-N bond is a sigma bond.
- The N=O double bond consists of one sigma bond and one pi bond.
**Solution:**
Count the sigma and pi bonds in the structure:
- C-C-C chain: 2 sigma bonds
- C-H bonds: 8 sigma bonds (3 + 2 + 3)
- C-N bond: 1 sigma bond
- N=O bond: 1 sigma bond and 1 pi bond
Total sigma bonds = 11
Total pi bonds = 1
Correct answer: **11 sigma and 1 pi bonds**.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Faab01dc0-572f-4647-affc-231aefa5eea9%2Fb418a1ae-83d8-4aa7-acb5-b0f0835cfb37%2Fpbz94zl_processed.jpeg&w=3840&q=75)
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