hey guys i was wondering about this question

[maskman`]

umm i was wonder about this question . in my chemistry book it has shown br losing all its electrons and combining ethene.

i was wondering whether this bond is co ordinate for not because it seems that ethene is donating electrons to the electron deficient bromine.

any help is much appreciated

 

[jamesnichols]

i have some theory actually about electrons. and for this to fit in with that and vice versa. i would say... it couldnt exist without the electrons

[hypervalent_iodine]

!

Moderator Note

jamesnichols,

 

Please stop hijacking threads with your pet theory. You have your thread, so please keep the discussion there.

[Iota]

i have some theory actually about electrons. and for this to fit in with that and vice versa. i would say... it couldnt exist without the electrons

What does that even mean? According to your theory on electrons "it" couldn't exist without electrons... that doesn't answer anything let alone what's being asked.

 

Maskman, what you're seeing in your book is probably the heterolytic fission of a bromine molecule (Br₂) as it approaches and becomes polarised by the electron dense ethene C=C bond. One of the bromine atoms takes the electrons from the bond that breaks in the bromine molecule, giving it a negative charge. The other atom from the bromine molecule (remembering bromine is diatomic so there are two bromine atoms per bromine molecule) becomes electron deficient and hence positively charged.

 

Your textbook shows the negatively charged bromine atom as Br: (the colon representing two of its electrons)... and the other as just Br (without any electrons), this does not mean it has no electrons though, because it does. It's just not necessary to show them because none of the others take part in the reaction...

 

In regards to the new bond being coordinate, remember that a coordinate bond is a bond where ONE of the two bonding chemical species provides BOTH of the two bonding electrons.

 

https://www.google.co.uk/search?hl=en&sugexp=les%3B&gs_rn=2&gs_ri=hp&tok=v_e5UD02GbXMVJSo8NH-_g&cp=8&gs_id=v&xhr=t&q=ethene+%2B+bromine&safe=off&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.&bvm=bv.41934586,d.d2k&biw=1230&bih=671&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=qX8SUf-LEMPs0gWSgIGoBg#um=1&hl=en&safe=off&tbo=d&tbm=isch&sa=1&q=bromine+%2B+ethene+mechanism&oq=bromine+%2B+ethene+mechanism&gs_l=img.3...616201.625099.2.625527.30.26.2.2.2.0.82.1126.26.26.0...0.0...1c.1.2.img.Ne1d0xgCjm8&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.&bvm=bv.41934586,d.d2k&fp=5301a610555fd68a&biw=1230&bih=671&imgrc=s3ir27dbw-ZtHM%3A%3B7fT_NgtAhhKekM%3Bhttp%253A%252F%252Fupload.wikimedia.org%252Fwikipedia%252Fcommons%252F5%252F5e%252FElectrophilic_reaction_of_bromine_with_ethene.png%3Bhttp%253A%252F%252Fwww.thestudentroom.co.uk%252Fshowthread.php%253Ft%253D1157377%3B1055%3B269

 

Look at this link and see if that is what's happening. Remember the curly arrows represent the movement of a PAIR of electrons.

[maskman`]

hahah thx a lot lota it helped a lot. i understand much more now

thank you