## Bond Length

304922790
Posts: 25
Joined: Fri Sep 29, 2017 7:04 am

### Bond Length

How do we know if the bond length is long or short? Is their a pattern? For example, in the lecture Lavelle arranged from long bond length to short bond length that HF<HCl<HI. How did he get that?

In another example, how would I arrange these molecules from shortest bond length to longest bond length:
B2^2- , B2, B2^- , and B2^2- .

Cali Rauk1D
Posts: 51
Joined: Fri Sep 29, 2017 7:03 am

### Re: Bond Length

we know the bond length due to how many electrons are being shared. The stronger the pull of the electrons the shorter bond length you will get. If there is a weak pull then the length will be long.

David Zhou 1L
Posts: 61
Joined: Fri Sep 29, 2017 7:04 am

### Re: Bond Length

Also, shorter bond lengths will result from smaller ions bonding together.

In the example with HF<HCl<HI, because atomic radii increase down the periodic table, the larger the halogen, the longer the bond length.

Rachel N 1I
Posts: 48
Joined: Thu Jul 27, 2017 3:00 am

### Re: Bond Length

The greater the bond strength the shorter the bond length. As there are more electrons, the pull force is greater which makes it stronger. For example a single bond has 2 electrons which gives it a weak bond strength and a long bong length. On the other hand, a triple bond has 6 electrons which gives it a strong bond strength and a short bond length.

Christy Zhao 1H
Posts: 50
Joined: Fri Sep 29, 2017 7:07 am

### Re: Bond Length

The larger the bonding atoms are, the distance between them is also larger, and the bond becomes weaker.

Lauren Seidl 1D
Posts: 51
Joined: Fri Sep 29, 2017 7:06 am

### Re: Bond Length

You can determine the relative bond lengths by looking at the number of single, double, and triple bonds. Triple bonds have the shortest bond length, and single bonds have the longest. Because some structures may have resonance, the bond lengths can be averaged in order to compare it to other structures.

Mishta Stanislaus 1H
Posts: 45
Joined: Fri Sep 29, 2017 7:04 am

### Re: Bond Length

We can determine the bond length by seeing how many electrons are being shared. The higher the bond order, the stronger the pull between the atoms and the shorter the length of the bond. Hope that helps!

Janet Nguyen 2H
Posts: 51
Joined: Fri Sep 29, 2017 7:05 am

### Re: Bond Length

All three of the examples come from an H bonded with a halogen so the structure of the bond is pretty much the same--H single bonded to the halogen. The difference in bond length comes from the size of the atom. Bond length is the measure of the center of one atom to the other, and since I has the biggest radius, the measure of its center to H's center is the largest and it has the longest bond length.

Michelle Lee 2E
Posts: 64
Joined: Thu Jul 27, 2017 3:01 am

### Re: Bond Length

Bond lengths and bond energies also also relate to electron affinity and differences in electronegativity. Shorter bond lengths (more bonds = doubles and triples), higher bond energy, larger difference in electronegativity.