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Double bond placement

Posted: Sun Oct 27, 2019 12:12 am
by Jorja De Jesus 2C
How can you tell where to put the double or triple bond, and where to put them if there are multiple? Can you put them anywhere because of resonance?

Re: Double bond placement

Posted: Sun Oct 27, 2019 1:04 am
by Bao Tram Nguyen
You can basically put them anywhere as long as they satisfy the octet rule (there are some elements that are exceptions to this because they have an expanded octet) meaning they have 8 valence electrons in the outer most shell after bonding with other atoms

Re: Double bond placement

Posted: Sun Oct 27, 2019 1:56 am
by Louise Lin 2B
Adding on to the poster above, the location of double and triple bonds will depend on where the octet rule can be accommodated. They cannot be replaced wherever “because of resonance,” because we must also determine if the atom has resonance structures in the first place. If there is resonance, then be sure to calculate the formal charges of the atoms in the structure you have set up.

Re: Double bond placement

Posted: Sun Oct 27, 2019 8:26 am
by claudia_1h
Double and triple bonds should be placed when the number of electrons does not allow for single bonds only + valence electrons for each atom, so electrons must be shared so they can be "counted twice" like he mentioned in lecture.

Re: Double bond placement

Posted: Sun Oct 27, 2019 9:54 am
by IScarvie 1E
In general, hydrogen likes to have one bond, oxygen likes two, nitrogen likes three, and carbon likes four. When you decide where to put double bonds or triple bonds, arrange them so that the most atoms have 0 formal charge and all the electrons are used, which usually follows the rules above.

Re: Double bond placement

Posted: Sun Oct 27, 2019 10:55 am
by Aayush Patel 3B
Like Dr. Lavelle did in lecture, I would add up all of the valence electrons present in the compound, also taking into account the charge of the compound, first. Then, I would place the element with the lower ionization energy as the central atom. Arrange the other atoms around the central atom and begin by giving a single bond to the central atom and the outer elements, as well as completing an octet for each outer atom. Then, see if you took account for all the electrons that need to be present in the compound, which is why you added them all up in the first place. Place the double or triple bond accordingly. If there is resonance, be sure to draw all of the Lewis structures to account for the different locations the double or triple bond may be.

Re: Double bond placement

Posted: Sun Oct 27, 2019 11:43 am
by Mariepahos4D
If there are multiple places where you could put the double or triple bond, you have resonance which means that you can draw the bonds anywhere in the lewis structure and that the actual experimentally observed bond length is an average of all the bond lengths.

Re: Double bond placement

Posted: Sun Oct 27, 2019 12:53 pm
by Bryce Barbee
I am pretty sure that you can put them anywhere as long as the formal charges are correct.

Re: Double bond placement

Posted: Sun Oct 27, 2019 4:47 pm
by Kimme Chun 1I
Our TA told the HONC rule where H likes to have 1 bond, O likes to have 2, N likes to have 3, and C likes to have 4. If any of these elements are in the molecule you are trying to draw, follow this rule to help.

Re: Double bond placement

Posted: Sun Oct 27, 2019 5:23 pm
by Maika Ngoie 1B
A good place to start is when looking at the number of electrons in a chemical species, and drawing the lewis dot structures, if a species is meant to have multiple bonds, the number of e- drawn should not match the total number of electrons needed.

Re: Double bond placement

Posted: Sun Oct 27, 2019 5:28 pm
by AronCainBayot2K
In most cases, double bond placement does not really matter as long as you fulfill the amount of electrons required to represent the molecule and that you follow the octet rule. If you see Hydrogen, Oxygen, Nitrogen, or Carbon, just note that Hydrogen prefers 1 bond, Oxygen (2), Nitrogen (3), and Carbon (4). Knowing those bond preferences would also make it easier to determine how to create the structure itself.

Re: Double bond placement

Posted: Sun Oct 27, 2019 5:34 pm
by Snigdha Uppu 1G
Double bond placement does not need to be in a specific spot as long as the octet rule is fulfilled for all the atoms.

Re: Double bond placement

Posted: Sun Oct 27, 2019 8:13 pm
by Cynthia Rodas 4H
You can use the octet rule, but I personally like to look at bonding preferences, such as how hydrogen has one bond, oxygen has two bonds, nitrogen has three bonds, and carbon has four bonds.

Re: Double bond placement

Posted: Sun Oct 27, 2019 8:29 pm
by Sanjana Borle 2K
Due to the concept of resonance, technically double and triple bonds can be anywhere as long as the satisfy the octet rule. Just make sure to count up all the electrons before you place the double and triple bonds in a certain location

Re: Double bond placement

Posted: Sun Oct 27, 2019 8:42 pm
by Jose Robles 1D
If a double bond occurs, then does that mean that the lone pairs are interchangeable without it effecting the lewis structure (for instance, like in nitrate NO3)? Like can the double bond occur at any pair of the oxygen without there being a difference?

Re: Double bond placement

Posted: Sun Oct 27, 2019 8:55 pm
by Sreyes_1C
they can be placed as long as they satisfy the octet rule but you should try drawing a structure with zero formal charge because it will be most stable. the double/triple bonds will help getting the formal charge to zero