How are bond angles determined?

[AnthonyEdwardsLec1]

The book repeatedly refers to how bond angles are determined experimentally, however I was wondering how exactly are they determined, for instance what types of experiments do chemists used to determine the angles?

[Maya Passananti 2L]

They're determined by the VESPR theory, which is all about valence electrons. Those that have more valence electrons will have certain electron pairs, causing bond angles different from their counterparts. So larger atoms in higher rows and periods which have more valence electrons will be different than smaller atoms.