MYTUTOR SUBJECT ANSWERS

290 views

Explain how the electron pair repulsion theory can be used to deduce the shape of, and the bond angle in, NH3.

Nitrogen has 5 valence electrons in its outer shell. Each Hydrogen has 1 valence electron in its outer shell, so the 3 Hydrogens donate 3 electrons in total. This gives 8 valence electrons in total. We can then divide this by 2 to calculate the number of electron pairs around the central nitrogen atom. As there are 4 valence electron pairs around the nitrogen, but only 3 Hydrogens, then we have 1 pair of electrons left over. (As a covalent bond, N-H in this example, requires 1 electron pair.) This left over pair of electrons is said to be a lone pair.

Each pair of electrons will repel the other pair of electrons, so the electron pairs will try and be as far away as possible from each other. As there are 4 pairs of electrons, we could say that the angle between them would be 109.5o. However, the lone pair that was left over actually repels more than the other pairs of electrons, so the actual angle between the hydrogens would be slightly less than this at ~107o.

The shape of the NH3 is referred to as trigonal bypramidal, as while the electron pairs are arranged tetrahedrally, the lone pair is considered to be invisible and so the NH3 does not look tetrahedral.

Matthew N. A Level Maths tutor, GCSE Maths tutor, A Level Chemistry t...

6 months ago

Answered by Matthew, an A Level Chemistry tutor with MyTutor

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

80 SUBJECT SPECIALISTS

£22 /hr

Rowan F.

Degree: Chemistry (Masters) - Bristol University

Subjects offered: Chemistry, Maths+ 1 more

Chemistry
Maths
Biology

“About Me  I am a first year Chemistry student at the University of Bristol and a long with my love for Chemistry I am also incredibly interested in Maths and Biology, enjoying studying both of them at A level. By tutoring that I hope ...”

£20 /hr

Eduardo S.

Degree: Bioengineering (Masters) - Sheffield University

Subjects offered: Chemistry, Spanish+ 3 more

Chemistry
Spanish
Physics
Maths
French

“About Me: I am a first year, Bioengineering MEng student at the University of Sheffield. I was born in Venezuela and have lived in 6 different countries in which I’ve learnt fluent English and proficient French, having already learnt ...”

£26 /hr

Ashley D.

Degree: Chemistry (Masters) - Durham University

Subjects offered: Chemistry, Science+ 4 more

Chemistry
Science
Physics
Maths
Biology
-Personal Statements-

“ A bit about me: Hey! I'm Ash and I have just finished my third year at Durham University studying Chemistry. I am currently on my summer vacation until the start of September which means I am readily available to tutor. I am...”

About the author

Matthew N.

Currently unavailable: for new students

Degree: Chemistry (4 Years) [MChem] (Masters) - Manchester University

Subjects offered: Chemistry, Maths

Chemistry
Maths

“About Me:I'm a third year student at the University of Manchester studying for my masters degree in Chemistry. The main purpose of my tutorials, aside from allowing you to pass your exams with a great mark, is to get you interested i...”

MyTutor guarantee

You may also like...

Posts by Matthew

Explain how the electron pair repulsion theory can be used to deduce the shape of, and the bond angle in, NH3.

Explain, in terms of sub-atomic particles, why the mass number of a magnesium atom is 24.

Find the derivative of the following expression: y=x^3+2x^2+6x+5.

Rearrange the equation y=3x+2 to make x the subject.

Other A Level Chemistry questions

What are covalent bonds?

What is a curly arrow?

Explain how the electron pair repulsion theory can be used to deduce the shape of, and the bond angle in, NH3.

What is benzene and describe the 2 models used to explain it's structure. Provide a piece of evidence to show which of these models is incorrect.

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