MYTUTOR SUBJECT ANSWERS

647 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...

9 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

97 SUBJECT SPECIALISTS

£24 /hr

Pooja D.

Degree: Medicine (Bachelors) - Birmingham University

Subjects offered:Chemistry, Science+ 6 more

Chemistry
Science
Physics
Maths
Biology
.UKCAT.
-Personal Statements-
-Medical School Preparation-

“I have tutored for the past 4 years and have gathered many ways of teaching concepts to students in a way that is easily-digestible and understandable. ”

£20 /hr

Natasha L.

Degree: Medicine (Other) - Bristol University

Subjects offered:Chemistry, Human Biology+ 8 more

Chemistry
Human Biology
English Literature
English Language
.UKCAT.
.BMAT (BioMedical Admissions)
-Personal Statements-
-Medical School Preparation-

“Hey! I'm Tash, a 3rd year medical student offering Science and English tutoring and pre-university mentoring. I can't wait to meet you and help you out! ”

Ben A. Mentoring -Medical School Preparation- tutor, Uni Admissions T...
£20 /hr

Ben A.

Degree: Medicine (Bachelors) - University College London University

Subjects offered:Chemistry, Physics+ 6 more

Chemistry
Physics
Maths
Biology
.UKCAT.
.BMAT (BioMedical Admissions)
-Personal Statements-
-Medical School Preparation-

“Hello,I am a first year medical student at University College London, When I was in sixth form, I helped tutor the younger years and I always enjoyed it, so I decided to keep it on in my university years.My subjects are the three m...”

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

Why does the First Ionisation Energy decrease down a group in the Periodic Table?

Which Medical Schools Should I apply to?

Predict the effect of an increase in pressure and temperature on the production of ammonia in the reaction: N2(g) + 3H2(g) <-> 2NH3 (g) , where the change in enthalpy is -92.4 kJ

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

View A Level Chemistry tutors

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

mtw:mercury1:status:ok