Determining Bond Angles

[Stella Nguyen 1J]

Hi everyone!

Whenever a question asks us to determine bond angles, would the bond angles always correspond to the molecular shape? For example, if the molecular shape is linear, the bond angle will always be 180°?

Thank you!

[Jessica Katz]

Yup! that's the only way we can determine the bond angle. And in some cases, we are only required to estimate by saying that the bond angle is going to be less than 109.5 degrees, when otherwise we would have to use the internet to find the exact degree.

[Ximeng Guo 2K]

Yes we use molecular shapes to determine bond angles.

[Kyle Dizon 3A]

Analyzing the shape will help provide a clear understanding of what the bond angles could possibly be. Directly answering your question, yes, a linear molecular shape has a bond angle of 180 degrees.

[Ansh Patel 2I]

Hi! Yes you're right, the molecular shapes are used to determine bond angles and you just have to memorize what angles correspond to the shapes.

[Danielle Goldwirth 3F]

Exactly!
Trigonal bipyramidal = 90
Tetrahedral = 109.5
Trigonal planar = 120
Linear = 180

Interesting to note is that in Sapling, we had to draw a cyclical 3-carbon ring, and since this forms a triangular shape, the bond angle here would be 60 degrees (the sum of the angles in an equilateral triangle is 180, so dividing that across three angles would give a 60 degree angle).

[Justin Lin 1B]

That's correct! The molecular shape of the molecule will give you its bond angles.

[Shalyn Kelly 3H]

Are lone pairs what make the bond angles "less than (<) 120" and such? And if there are two lone pairs then the bond angel would be less than less than (<<)?

[reyvalui_3g]

Are lone pairs what make the bond angles "less than (<) 120" and such? And if there are two lone pairs then the bond angel would be less than less than (<<)?

Yes, that is correct, the lone pairs will make the bond angles smaller since they occupy a larger volume of space.

[Hannah Lechtzin 1K]

Yes! The bond angles are experimentally determined based on molecular shape, so that is how you will determine the bond angle.