Module 2// Foundations in chemistry

Question 1

what is the difference between atom economy and percentage yield?

Answer 1

Atom economy is the percentage of products of a reaction that successfully converted to the desired product
Whereas percentage yield is how much product was lost in the reaction

Question 2

Give 3 reasons why the percentage yield is not 100%

Answer 2

• reversible reaction
• product lost in transfer
• reactants not used up

Question 3

electron configuration

Answer 3

A shorthand representation that shows how electrons occupy sub-shells in an atom

Question 4

Shells (aka energy levels)

Answer 4

A group of atomic orbitals w the same principle quantum number= n

Question 5

What are shells divided up into?

Answer 5

Shells are divided up into sub-shells (s-,p-,d-,f-)

Question 6

Sub-shell

Answer 6

A group of orbitals of the same type within a shell

Question 7

Atomic orbital

Answer 7

A region around the nucleus that can hold up to 2 electrons w OPPOSITE spins

Question 8

What is meant by the term ‘spin’ in an atomic orbital

Answer 8

The 2 electrons that occupy an orbital must spin in opposite directions
= Aka SPIN-PAIRING

Question 9

Up to how many electrons can s-orbitals hold

Answer 9

s-orbitals can hold up to 2 e-

Question 10

Up to how many electrons can p- orbitals hold

Answer 10

p-orbitals can hold up to 6 e-

Question 11

Up to how many electrons can d-orbitals hold

Answer 11

d-orbitals can hold up to 10 e-

Question 12

Up to how many electrons can f- orbitals hold

Answer 12

f-orbitals can hold up to 14 e-

Question 13

Why are orbitals within sub-shells occupied singly first

Answer 13

Orbitals within sub-shells are occupied singly first because orbitals within a sub-shell have the same energy

1e- occupies each orbital before pairing starts— this prevents any repulsion between paired e- until there is no further orbital available at same energy level

Question 14

relative isotopic mass

Answer 14

The mass of an atom of an isotope compared with 1/12th of the mass of an atom of carbon 12

Question 15

relative atomic mass

Answer 15

the weighted mean mass of an atom of an element compared with 1/12th of the mass of an atom of carbon 12

Question 16

amount of substance

Answer 16

the quantity whose unit is the mole, used as a means of counting any species such as atoms, ions + molecules