continued

Question 1

Electromagnetic spectrum?

Answer 1

Electro magnetic radiation: energy transmitted as waves with spectrum of different frequencies
- RMIVUXG
- Increasing frequency/ energy & decreasing wavelength

Question 2

What does atomic emission demonstrate?

Answer 2

that energy of electrons isn’t continuous but electrons hv discrete energies

Question 3

What does the atomic emission spectra provide evidence for?

Answer 3

electrons are present within an atom in diff energy levels/quantum shells
- when gaseous atoms given energy (heating/current) electrons r temp excited/move into higher energy levels -> eventually return back to lower, more stable & emit electromagnetic radiation/discrete energies

Question 4

How do excited electrons demonstrate the evidence that electron energies aren’t continuous?

Answer 4

• shows us atoms don’t emit radiation across the whole of the EM spectrum - only specific frequencies emitted - which r unique to an individual element
• all atoms of particular element radiate same set of frequencies

Question 5

What is evidence that the energy of electrons in atoms can only hv fixed/certain values & not a continuous range of values?

Answer 5

the fact only certain frequencies of EM radiation are emitted from the atoms

Question 6

What is the basis of quantum theory?

Answer 6

the energy of electrons is said to be quantised/discrete (discrete) rather than continuous (changes gradually over range of values)

Question 7

What is atomic emission?

Answer 7

an analytical technique used to identify elements within a substance
- emission spectrum produced aka line spectrum

Question 8

E.g. Describe atom with three different energy levels?

Answer 8

• Ground state = shell closest to nucleus aka n=1
• Shells have discreet (fixed) energy levels - Electrons can move from one quantum shell to another
• When electron absorbs energy moves up to a higher quantum shell aka excited
• Eventually electron moves back down and releases some energy

Question 9

What does line spectrum/emission spectrum show?

Answer 9

shows the frequency of light given out when an electron moves down energy levels - see as coloured bands

• Every element has a different electron configuration so will absorb and emit different frequencies of radiation -unique to diff element

Question 10

First ionisation energy definition?

Answer 10

The energy required to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ion
(endothermic)

Question 11

First Ionisation energy explained?

Answer 11

to remove an electron from an atom - energy needed to overcome electrostatic attraction between the electron & nucleus
- the larger the attraction, the larger the ionisation energy (alw +)

Question 12

Equation of of first ionisation energy?

Answer 12

E (g) –> E+(g) + e-

Question 13

3 factors affecting Ionisation Energy

Answer 13

1. Nuclear charge (the more protons, more positively charged nucleus, stronger attraction)
2. Size (greater distance between outer electron & positive nucleus = less attraction)
3. Shielding (no. electrons between outermost electron & nucleus - reduces reaction)
   (4. spin)

Question 14

Second ionisation energy definition?

Answer 14

The energy required to remove 1 electron from each 1+ ion in one mole of gaseous ions to form 1 mole of gaseous 2+ ions

Question 15

Equation of second ionisation energy?

Answer 15

E+ (g) –> E2+ (g) + e-

Question 16

Why does the first ionisation energy decrease as you go down a group?

Answer 16

1. Nuclear charge increases a lot
2. shell number increases (higher energy levels)
3. atomic radius increases
4. shielding (by inner electron) increases (outer experiences increased repulsion)
   - nuclear charge increased makes harder to remove electrons so would increase IE
   - BUT other factors make easier to remove electrons - outweigh increased nuclear charge

(provides evidence that shells exist)

Question 17

Why does the ionisation energy across a period increase?

Answer 17

1. nuclear charge increases (as no. protons increases)
2. shielding stays roughly the same (as all extra electrons at roughly the same energy level)
3. atomic radius decreases slightly
   - 1 & 3 mean it requires more energy to remove

Question 18

Why does successive ionisation energy increase within each shell?

Answer 18

• electrons r being removed from an increasingly positive ion…
• electron-electron repulsion within shell decreases so - decrease in energies of remaining electrons so - why there is a steady increase in IE
• big jumps in IE = new shell is broken into aka electron being removed from shell closer to nucleus - evidence for quantum shells

Question 19

Why does the electron being removed from the first quantum shell/1s orbital require the highest IE?

Answer 19

it experiences zero repulsion so - energy decreases

Question 20

Why do successive ionisation energies increase?

Answer 20

*for a given atom - the energy value the electron has when it reaches an infinite distance from the nucleus aka energy of electron when removed (where it no longer experiences an attractive force from the nucleus) will alw be the same regardless of where in atom it came from
* 1st IE comes from highest energy level
- if electron alr has high energy - energy need to be removed not very large
- if electron in orbital of low-energy shell - will need to gain considerably more energy to be removed…
- IE = energy of electron when removed-energy of electron when in orbital so…
- IE for particular electron in given atom depends SOLELY on its energy in its orbital

Question 21

A graph of successive ionisation energies can…

Answer 21

1. tell u which group an element belongs to: count how many electrons r removed b4 first big jump to group
2. be used to predict electronic structure: working from right to left - count how many points there r b4 each big jump - to find how many electrons in each shell (starting w the 1st)

Question 22

What are the factors that affect the energy of an electron?

Answer 22

• the orbital in which the electron exists (effect: higher energy level/orbital increases energy)
• the nuclear charge of the atom (effect: decreases energy as attracted more strongly)
• the repulsion (shielding) experienced by the electron from all other electrons present (increases energy as shielded from nuclear charge)