Thanks for letting us know Hussein, there's a video on naming multiple functional groups below.

Here's a quick List of priority functional groups from highest to lowest:

Carboxylic acids, Esters, Amides, Aldehydes, Ketones, Alcohols, Thiols, Amines, Ethers, Thioethers, Alkenes, Alkynes, Alkyl Halides

The higher priority group will have less hydrogens, this is why it is numbered this way. 

Yes it's because those lone pairs are considered to be vinyl lone pairs.

Vinyl lone pairs are on the atom that is double bonded.

Allylic lone pairs are one atom over and is the one next to a double bond. As shown in the image below. 

Allylic lone pairs will participate in resonance. While vinyl lone pairs do not participate in resonance. Below you'll find an example of different allylic and vinyl lone pairs. These also can relate to hybridization as shown below. 

Ayanna Harrison thanks for letting us know, it is cyclopropane, we reuploaded the video and fixed this.  

Assigning Priorities and finding the R and S configurations is found here:

Yay! We are so happy to hear that! 

Hey Jessica, the resonance structures are drawn correctly because N starts off with 2 lone pairs and then each resonance structure only has 1 lone pair since it is now double bonded to C. 

When moving electrons for resonance structures you don't have to show all the lone pairs all the time, only the ones that are moving has to be shown. Most professors will skip drawing all lone pairs and expect you to know that they are still there. So knowing your formal charges and bonding patterns is important. You'll find the explanation with formal charges below. 

You'll soon see this when you cover functional groups, this is how we draw an aldehyde. This is a specific case whenever you see that CHO. We can either show the H or not but it would look like this if we didn't show the H at the end. 

This can depend on your professor and/or the textbook they are using. If your professor prefers that way then I recommend following it. But these methods and the below video can still help you understand how to draw resonance structures and where to start and stop. 

It all comes back to the formal charges and the total number of valence electrons. When you aren't sure of the structure always check if you have the correct number of electrons (octet rule) and if the formal charges are neutral. Neutral structures want every atom to have a neutral formal charge. When there is a net charge of let's say -1 then the more electronegative atom will have the negative formal charge. 

Also remember Carbon must have a full octet meaning it wants 4 bonds, this is why we don't connect them all in the same line C-O-O that doesn't give us a valid structure.