MYTUTOR SUBJECT ANSWERS

499 views

How do I predict the shape and bond angle of an molecule?

Electron pairs arrange themselves so they are as far apart as possible (electron pair repulsion theory). In a covalent compound, the number of electron pairs around the central atom determines the shape of the molecule. 

An electron pair shared between two atoms is called a bonding pair (BP)

An electron pair on one atom only- not shared- is called a lone pair (LP)

BeClhas two bonding electron pairs shared between the Be2+ ion and the two Clions. Cl-Be-Cl  bond angle = 180 degrees (linear)

BF has three bonding electron pairs shared between the B3ion and the three Fions. The  bond angle = 120 degrees (trigonal)

CH4 has four bonding electron pairs shared between the C4- ion and the four H+ ions. The  bond angle = 109.5 degrees (tetrahedral)

However when we introduce lone pairs to the molecules it distorts the bond angle because of electron pair repulsion.

Electron pair repulsion theory tell us that LP-LP repulsion > LP-BP repulsion > BP-BP repulsion.

Therefore a molecule containind three bonding pairs and one lone pair like NH(four electron pairs all together) gives rise to a distorted bond angle because the lone pair repels the other bonding pairs which decreases the bond angle from 109.5 (tetrahedral) to 107 (pyrimidal).

Tolu T. GCSE Biology tutor, GCSE Chemistry tutor, GCSE Physics tutor,...

2 years ago

Answered by Tolu, an A Level Chemistry tutor with MyTutor

Still stuck? Get one-to-one help from a personally interviewed subject specialist

80 SUBJECT SPECIALISTS

£30 /hr

Els D.

Degree: Veterinary Science BVSC (Bachelors) - Bristol University

Subjects offered: Chemistry, Science+ 4 more

Chemistry
Science
Dutch
Biology
.BMAT (BioMedical Admissions)
-Personal Statements-

“Often students are too shy to ask questions in the classroom - and this can be detrimental to their learning. During my own studies at both GCSE and A-Level, I found one to one tutition to be invaluable in helping me get to grips with all those...”

£20 /hr

Fabiha A.

Degree: Biomedical Science (Bachelors) - Kings, London University

Subjects offered: Chemistry, Science+ 2 more

Chemistry
Science
Maths
Biology

“About me I am currently studying Biomedical Science at King's College London because it combines my twomost loved subjects, Biology and Chemistry. My enthusiasm for all things science make me want to keep learning and also use my kno...”

£26 /hr

Tabitha E.

Degree: Medicine (Bachelors) - Durham University

Subjects offered: Chemistry, Psychology+ 4 more

Chemistry
Psychology
History
Biology
-Personal Statements-
-Medical School Preparation-

“Hi, I'm Tabby, a medical student at the University of Durham. I would really love to help with anything and everything I can!”

About the author

£20 /hr

Tolu T.

Degree: Applied bio pharmaceuticals biotechnology and entrepreneurship (Masters) - Nottingham University

Subjects offered: Chemistry, Physics+ 2 more

Chemistry
Physics
Maths
Biology

“First class Biochemistry graduate with a wealth of teaching experience, ready to help you improve your grades.”

MyTutor guarantee

You may also like...

Posts by Tolu

How do I predict the shape and bond angle of an molecule?

What is the bonding structure of a metal

Other A Level Chemistry questions

Why do ionisation energies increase across a period?

What is a buffer?

Describe a procedure to form an ester from a sample of carboxylic acid.

Although carbon dioxide is a linear molecule it is still a greenhouse gas. Explain why that is.

View A Level Chemistry tutors

Cookies:

We use cookies to improve our service. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok