Atomic Structure

Question 1

What is an orbital?

Answer 1

A cloud of negative charge

Question 2

What are the different sub levels?

Answer 2

S, P, D, F (in order of lowest to highest energy level)

Question 3

How many electrons can an orbital be occupied by?

Answer 3

Maximum of 2

Question 4

How many electrons can an s sub level hold? How many orbitals?

Answer 4

• 2 electrons
• 1 orbital

Question 5

How many electrons can a p sub level hold? How many orbitals?

Answer 5

• 6 electrons
• 3 orbitals

Question 6

How many electrons can a d sub level hold? How many orbitals?

Answer 6

• 10 electrons
• 5 orbitals

Question 7

What is an energy level?

Answer 7

A region of empty space occupied by electrons

Question 8

What are energy levels made up of?

Answer 8

Different number of sub levels

Question 9

What are sub levels made up of?

Answer 9

Different number of orbitals

Question 10

What is the order of sub levels?

Answer 10

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s

Question 11

What does a mass spectrometer do?

Answer 11

Gives information about:
- RAM of element
- Relative abundance of its isotopes
- Relative molecular mass of molecule if used to analyse a compound

Question 12

What is the first step of TIME OF FLIGHT mass spectrometry (electrospray ionisation)?

Answer 12

• Sample dissolved in volatile solvent
• Injected through fine hypodermic needle at high pressure
• High voltage applied to end of needle —> each particle gains H+ ion (creates fine mist)
• Solvent evaporates —> XH+ ions attracted towards negative plate where they are accelerated

X(g) + H+ —> XH+(g)

Question 13

What is the first step of TIME OF FLIGHT mass spectrometry (electron impact)?

Answer 13

• Sample is vaporised
• High energy electrons fired at sample using electron gun
• One electron knocked off each particle —> become +1 ions

CH4(g) —> CH4+ + e-

Question 14

What is the second step of TIME OF FLIGHT mass spectrometry?

Answer 14

Acceleration:
- Positive ions accelerated by electric field
- Electric field gives same kinetic energy to all ions
- Lighter ions = greater acceleration (but same energy)

KE = ½mv²

Question 15

What is the third step of TIME OF FLIGHT mass spectrometry?

Answer 15

Ion drift:
- Ions enter region with no electric field
- Drift through at the same speed as they left the electric field
- So lighter ions still drift at higher speeds
- Ions with different masses have different time of flights

t = d/v
t = d√m/2KE v measured in ms-¹

Question 16

What is the fourth step of TIME OF FLIGHT mass spectrometry?

Answer 16

Detection:
- Positive ions hit negatively charged electric plate
- Hit detector plate —> positive ions discharged by gaining electrons from plate
- Generates movement of electrons
- Electric current is measured
- Size of current ∝ number of ions hitting plate (more ions = bigger current)

Question 17

When is electospray ionisation used?

Answer 17

Used on substances with higher molecular mass

Question 18

When is electron impact used?

Answer 18

Used in substances with lower formula mass

Question 19

How do you calculate relative atomic mass?

Answer 19

Combined mass of all isotopes / Combined abundance of all isotopes

Question 20

What is the 1st ionisation energy?

Answer 20

The energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions

Question 21

What is the equation for the 1st ionisation energy of oxygen?

Answer 21

O (g) —> O+ (g) + e‐

Question 22

What are the 3 factors that affect ionisation energy?

Answer 22

• Nuclear charge
• Distance from nucleus
• Shielding

Question 23

What is the 2nd ionisation energy?

Answer 23

The energy needed to remove an electron from each ion in 1 mole of gaseous 1+ ions

Question 24

What is the equation for the 2nd ionisation of oxygen?

Answer 24

O+ (g) —> O²+ (g) + e-

Question 25

Why is the 2nd ionisation energy greater than the 1st ionisation energy?

Answer 25

The electron is being removed from a positive ion, which requires more energy