Does it come with some nitrogen blue holes 3 at 120 degree instead of 107 degree? carbon black holes 3 and 2, oxygen red holes 1 also helpful.

It sounds like you are interested in geometries of C, N, and O compounds which involve double and triple bonds and this means atoms that are trigonal planar (120 degree holes) and linear (180 degree holes). This kit does not have such atoms ( I don't know any kits that do) but does have trigonal bipyramid atoms (5 holes) that can be used for trigonal planar geometries and octahedral atoms (6 holes) that can be used for linear geometries. Be aware that few molecules actually have 120 degree bond angles owing to different electron pair repulsions of the various bonds and lone pairs. Therefore, rather than using the 5 hole atom for trigonal planar geometries of C and N, I think you are better off using the kit's existing C, N, and O atoms for bonding situations where these atoms have trigonal planar or linear geometries and using the long, flexible bonds to represent the double and triple bonds that are involved. This gives reasonable structures and clearly highlights the double and triple bonds. In my opinion, all model kits would be improved if the C, N, and O atoms were all tetrahedral (4 holes) so you could also include lone pairs of electrons in your model. Seeing these lone pairs is important to understanding the molecular geometry of molecules containing nitrogen and oxygen and more than compensates for larger errors in the bond angles. Another improvement for this kit would be to remove all but two of the 5-hole and 6-hole atoms (rarely needed) and increase the number of carbon and hydrogen atoms.

Are the bonds flexible enough for representing chair configurations?

If you are referring to chair and boat configurations of cyclohexane the answer is yes since no bond flex is really required. If some flex is required for a particular molecule you have in mind you could use the longer flexible bonds to construct your model. It won't be beautiful but it will probably give an acceptable structure.

Are the bonds easy to remove and put on? I have the molymod version and they require a lot of strength to put on and remove. Bummer.

Yeah super easy to put together and for the little short bonds that might be hard to grab there is a tool that comes with it to help pull them apart.

Can this model make fisher projections?

Hi there S.M, There is an excellent youtube video that explains how to use the Molecular Kit with Fisher projections. It only goes for 2 minutes and sums it really well https://www.youtube.com/watch?v=tTc19BDXVG8 Anything else or how we can help, please let us know Regards Peter

Product Dimensions	31.5 x 21.84 x 6.1 cm; 680 g
Manufacturer recommended age	15 years and up
Item model number	ZY-ghm-0902-42
Educational Objective(s)	Chemistry Concept Development Skills
Number of Puzzle Pieces	239
Assembly Required	Yes
Batteries Required?	No
Batteries Included?	No
Material Type(s)	Plastic
ASIN	B01NCU854K

KEXMY Organic Chemistry Model Kit - Molecular Model Student or Teacher Pack with Atoms, Bonds and Instructional Guide, 239 Pieces

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