KA3- Shapes of molecules & polyatomic ions

Question 1

What are Lewis Diagrams?

Answer 1

They are used to represent bonding and non-bonding pairs in molecules and poly-atomic ions

Question 2

What is diative covalent bonding?

Answer 2

when a covalent bond is formed, 2 atomic orbitals jooin together to form a molecular orbital.
sometimes one of the atoms can provide both electrons that form the covalent bond (diative covalent bond)

Question 3

What must be considered when determining a shape of a molecule

Answer 3

• all outer shell electrons
• the idea that a molecule adopts a shape that minimises the repulsion of the electrons of the central atom that repel one another

process is called VSEPR

Question 3

How can the shape of a molecule (or polyatomic ion) be determined?

Answer 3

no. of electron pairs = {no. of outer shell electrons on the central atom and no. of bonded atoms (- charge if ionic)}/2

Question 4

What would be the orientation of molecules from total no. of electron pairs 2-6?

Answer 4

2 linear
3 trigonal planar
4 tetrahedral
5 trigonal pyramidal
6 octahedral

Question 5

unbonded electron shapes

3 electron pairs

Answer 5

trigonal planar -> (2b, 1ub) bent

Question 6

unbonded electron shapes

4 electron pairs

Answer 6

tetrahedral-> (3b, 1ub) trigonal pyramid
-> (2b, 2ub) bent

Question 7

unbonded electron pairs

5 electron pairs

Answer 7

trigonal bipyramidal -> (4b,1ub) seesaw
-> (3b, 2ub) t-shaped
-> (2b, 3ub) linear

Question 8

unbonded electron pairs

6 electrons

Answer 8

octahedral-> (5b, 1ub) square pyramidal
-> (4b, 2ub) square planar

Question 9

why do bonding electrons not repel as much as non-bonding ones?

Answer 9

because they are attracted by 2 nuclei

Question 10

Put electron pair repulsions in order from most to least strongest?

Answer 10

1. non-bonding to non-bonding
2. non-bonding to bonding
3. bonding to bonding