Reactivity

Question 1

What are the 8 structures compounds can have, the bond angles and an example for each

Answer 1

1. Linear

180˚

e.g. O=C=O

2. Trigonal planar

120˚

e.g. BF3 or BCl3

3. Tetrahedral

109. 5˚
     e. g. CH4

4. Pyramidal

107˚

e.g. NH3

5. Non-linear

104. 5˚
     e. g. H2O

6. Trigonal bipyramidal

2x 90˚, 3x 120˚

e.g. PCl5

7. Octahedral

90˚

e.g. SF6

8. Square planar

90˚

e.g. cis-platin

Question 2

Whats the octet rule?

What orbitals are involved in the octet rule?

Answer 2

The octet rule refers to the tendancy of atoms to prefer to have 8 electrons in the valence shell (outer most shell)

DEFINITION: a stable arrangment is attended when the atom is surrounded by 8 electrons. This octet can be made up by own electrons and shared electrons

Only the S and P orbitals are involved in the octet rule

Question 3

What are radicals?

Answer 3

A radical is a species with an unpaired electron.

They are highly reactive and unstable

Question 4

why is there polarity in moleucles?

Answer 4

Due to the difference in polarity between the bonded molecules

Question 5

Whats the definition of a reaction?

Answer 5

The electron flow from one functional group to another

Question 6

Whats a intermolecular reaction?

Answer 6

If the 2 functional groups present are in 2 different molecules

Question 7

Whats an intramolecular reaction?

Answer 7

If the 2 functional groups present are in the same molecule

Question 8

What do curly arrows represent?

Answer 8

The transfer of electrons

Question 9

Whats a nucleophile?

Answer 9

The source of electrons (electron donor)

Question 10

Whats an electrophile?

Answer 10

The functional group/atom that recieves electrons (electron acceptor)

Question 11

Whats more reactive, an aldehyde or a ketone?

Answer 11

Aldehyde is more reactive than a ketone

Question 12

Whats the equation for the reversable reaction that forms a hemi-acetal?

Answer 12

aldehyde + alcohol –> hemi-acetal

Question 13

Complete this reversable reaction…

Hemi-acetal + alcohol –>

Answer 13

hemi-acetal + alcohol –> acetal + H₃O⁺

Question 14

Whats more stable, urea or an amide?

Answer 14

Urea is more stable than an amide

Question 15

Whats a sigma bond and whats a pi bond?

Answer 15

Sigma bond: this is a single bond formed from two overlapping S orbitals

Pi bond: This is a double bond formed from 2 sideways overlapping P orbitals

Question 16

Whats does the following image represent?

Answer 16

The arrow means that the pull of electrons is towards the arrowhead (direction of polarity).

NOTE: a bar should be drawn at the end of arrow to show end of polarity of bond

Question 17

Whats a resonance structure?

Answer 17

A compound with a different electronic arrangement

there is electron pair movement with out the sigma bonds being broken

(look at lecture 5 for how to make resonance structures)