Shapes of Molecules and Polyatomic Ions 1.3

Question 1

What are Lewis Diagrams

Answer 1

Electron dot to dot diagrams used to represent bonding and non-bonding pairs in molecules and polyatomic ions

Question 2

What are Dative Covalent Bonds

Answer 2

One atom provides both electrons that form a covalent bond

Question 3

How can we predict molecular shapes

Answer 3

Consider all outer shell electrons (valence electrons) repel each other. Therefore the molecule adopts whichever 3D geometry minimises the repulsion. Both bonding and non-bonding pairs are considered. This is called the Valence Shell Electron Pair Repulsion (VSEPR) theory

Question 4

What is the formula to predict molecular shape

Answer 4

No of electron pairs= number of outer electrons on central atom + number of bonded atoms - charge / 2

Question 5

What are the names of molecular shape

Answer 5

2= linear (180°) (CO2)
3= trigonal planar (120°) (BF3, NO2)
4= tetrahedral (109.5°) (CH4, NH3, H2O)
5= trigonal bipyramidal (120°/90°) (SF4)
6= octahedral (90°/180°) (SF6, BrF5)

Question 6

What are the bonds in order of decreasing repulsion strength

Answer 6

non-bonding/non-bonding
non-bonding/bonding
bonding/bonding