# Comparing Bond Lengths in Pairs of Bonds

• Qube
In summary, when comparing bond lengths, the number of bonds and the size of the atoms involved are important factors. The stronger the bond, the shorter the bond length. In the given choices, options 2 and 5 can be eliminated due to the presence of triple bonds. The remaining options (1, 2, and 4) require further analysis, taking into consideration factors such as electronegativity, strength, and atomic size. It can be determined that sulfur, being a smaller atom compared to silicon, would result in a shorter bond length in the pair C-S than in the pair C-Si.

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## Homework Statement

In which of the following pairs of bonds is the shorter bond length not followed by the longer
bond length?

(1) S―O, P―O
(2) C≡C, C=C
(3) C=O, C=S
(4) C―Si, C―S
(5) N≡O, N=O

## Homework Equations

Bond length is determined by the bond order (number of bonds) and bond length is also an indicator of bond strength. The stronger the bond, the shorter the bond. The more bonds, the shorter the bonds.

## The Attempt at a Solution

Choices 2 and 5 can be immediately eliminated since the triple bonds are obviously shorter than the double bonds.

I'm having a hard time narrowing down between the remaining choices (1, 2, and 4). How do I go about determining which bonds are shorter or longer? Does it depend on electronegativity? Strength?

The size of the atoms (more precise: the outer electrons) is important, too. If you look downwards within a chemical group, atom diameters increase as more and more shells get filled.

Well sulfur is a smaller atom than silicon according to periodic trends so 4 must be the answer.

The bond length depends on the distance of the 2 nuclei one to another and the density of the electronic 'cloud' between them. The larger the atomic radius and the more electrons appear in a bond, the effects are just opposite.

Other factors?

As a scientist, it is important to consider multiple factors when comparing bond lengths. Electronegativity, bond strength, and bond order can all play a role in determining bond length. However, it is also important to consider the specific atoms involved in the bond and their size. In general, as the size of the atoms involved increases, the bond length also increases.

For example, in choice 1, sulfur (S) is larger than oxygen (O), so the S-O bond is longer than the P-O bond. In choice 3, oxygen is more electronegative than sulfur, so the C=O bond is shorter than the C=S bond. In choice 4, sulfur is larger than silicon (Si), so the C-S bond is longer than the C-Si bond.

In order to accurately determine the bond lengths in these pairs, it would be helpful to consult a table or database of known bond lengths for the specific atoms involved. This information can also be experimentally determined using techniques such as X-ray crystallography or spectroscopy.

Overall, the comparison of bond lengths requires a comprehensive understanding of various factors and cannot be determined solely based on one factor. As a scientist, it is important to consider all relevant information and use appropriate methods to accurately determine bond lengths.

## 1. What is a bond length?

A bond length is the distance between the nuclei of two atoms that are bonded together. It is typically measured in units of angstroms (Å) or picometers (pm).

## 2. How are bond lengths determined?

Bond lengths are determined through various experimental techniques, such as X-ray crystallography, spectroscopy, and electron diffraction. These methods involve measuring the distance between the nuclei of bonded atoms and can provide accurate values for bond lengths.

## 3. Why is it important to compare bond lengths in pairs of bonds?

Comparing bond lengths in pairs of bonds allows scientists to understand the nature of the chemical bonds between atoms. The lengths of bonds can indicate the strength and type of bond present, which can greatly impact the physical and chemical properties of a molecule.

## 4. What factors can affect bond lengths?

The type of atoms involved, the number of bonds between them, and the presence of neighboring atoms can all affect bond lengths. Additionally, the presence of multiple bonds, such as double or triple bonds, can also impact bond lengths.

## 5. How do bond lengths differ between single, double, and triple bonds?

Bond lengths generally decrease as the number of bonds between two atoms increases. This means that single bonds have longer bond lengths compared to double and triple bonds. This is due to the increased strength of multiple bonds, which allows atoms to be held closer together.