Atomic Structure

Question 1

What is mass number?

Answer 1

Number of protons and neutrons in at atom

Question 2

What is atomic number?

Answer 2

Number of protons in an atom

Question 3

What is relative atomic mass?

Answer 3

Average mass of one mole of atoms of an element relative to 1/12 the mass of one mole of carbon 12

Question 4

Why is the next ionisation energy of Mg2+ higher than that of F-?

Answer 4

Same shielding
e- removed comes from the same position
Mg2+ has a higher nuclear charge as it has mor protons
So stronger attraction between outer e- and nucleus

Question 5

What is the electron configuration of Cr?

Answer 5

1s2 2s2 2p6 3s2 3p6 4s1 3d5

Question 6

What is the electron configuration of Cu?

Answer 6

1s2 2s2 2p6 3s2 3p6 4s1 3d10

Question 7

General trend in ionisation energy down a group?

Answer 7

Decreases
Increased nucelar charge is cancelled out by shielding
More occupied energy levels
Outermost e- less attracted to the nucleus
Less energy required to remove

Question 8

General trend in ionisation energy across a period

Answer 8

Increases
Nuclear charge increases
Shielding stays the same
Electrons removed come from the same energy level
Distance between outermost e- and nucleus slightly decreases

Question 9

Why is the first ionisation energy of Be higher than B?

Answer 9

e- removed from B comes from the 2p sub shell
e- removed from Be comes from 2s sub shell
2p is slightly further from the nucleus
Shielding stays the same
e- from B is less strongly attracted to the nucleus

Question 10

Why is the first ionisation energy of Be more than Mg?

Answer 10

e- removed fro: Be comes from he 2nd energy level
e- removed from Mg comes from the third energy level
Shielding increases
Distance between outermost e- and nucleus increases but is cancelled out by the increase in nuclear charge

Question 11

What is the trend in successive ionisation energies?

Answer 11

Increases
e- removed comes from an increasingly positive nucleus
e- are more strongly attracted to the nucleus
So require more energy to be removed

Question 12

How is the abundance of an isotope measured in ToF?

Answer 12

Positive ions hit a negatively charged plat e
Gains an e- which creates a flow of e-
Size of the current is proportionally to abundance

Question 13

What is electron bombardment?

Answer 13

Electron gun fires electrons at an atom
This e- hits off another e- to form a positive ion

Question 14

What is electro spray ionisation?

Answer 14

Sample dissolved in a volatile solvent
Put through a hypodermic needles which is attached to a high voltage energy supply
Creates a fine mist and the sample gains a proton

Question 15

What is the abundance of Cl isotopes?

Answer 15

35 - 75%
37 - 25%

Question 16

What is the abundance of H and C isotopes?

Answer 16

Isotopes of these elements are rare

Question 17

What is the abundance of Br isotopes?

Answer 17

79 - 50%
81 - 50%