2 atomic structure

Question 1

structure of an atom

Answer 1

positively charged nucleus
‘cloud’ of negative charge

electrostatic attraction betw pos nucleus and neg charged electrons – holds it tgt

Question 2

define isotope

Answer 2

different atoms of the same element
same protons
but diff number of neutrons

Question 3

speed of light? (in section 2 of data booklet)

Answer 3

3.00 x 10^8 m/s

Question 4

excited state electrons are further / closer to the nucleus

Answer 4

further (higher energy level)

Question 5

in a line emission spectrum of hydrogen, describe the lines

Answer 5

they get closer toegther towards the blue end of the spectrum (convergence towards the higher energy end)

Question 6

what does it mean when lines converge towards the higher energy end in an emission spectrum

Answer 6

the electron is reaching its maximum amt of energy = ionisation energy of the electron

Question 7

who observed line emission spectra

Answer 7

Johannes Balmer

(the balmer series is in the visible spectrum)

Question 8

lines in an emission spectrum correspond w the electron jumping from _____ levels to the ______ energy level

Answer 8

higher

second

Question 9

when an electron jumps to n3, what is the region and energy level?

Answer 9

infrared

low

Question 10

when an electron jumps to n2, what is the region

Answer 10

visible

Question 11

when an electron jumps to n1, what is the region and energy

Answer 11

ultraviolet

high

Question 12

how to calculate the number of electrons each principal quantum number can hold?

Answer 12

2n^2

Question 13

how many electrons can the principal quantum number 3 and 4 hold?

Answer 13

well yknow n=1 can have 2 and n=2 can have 8 BUT as it turns out
3 = 18
4 = 32

Question 14

what is the sequence of letters for the subshells! + how many electrons can each have

Answer 14

s p d
2 6 10

Question 15

s and p orbital shapes

Answer 15

s is just a sphere around the centre

p is a dumbell shape? along the axes so like an hourglass

Question 16

what is the ground state of an atom

Answer 16

most stable electronic configuration with lowest amount of energy

Question 17

what is the Aufbau principle

Answer 17

ground state is acheived by filling subshells with lowest energy first
(does not follow pattern above n=2)

Question 18

exception to subshell increase in energy as follows: s < p < d < f

Answer 18

3d subshell has slightly higher energy level than 4s = 4s filled first

Question 19

what does it mean when orbitals are ‘degenerate’?

Answer 19

orbitals in the SAME subshell have the same ENERGY (1s=2s=3s=4s)

Question 20

subshells can be further divided into orbitals, which each can hold ___ electrons

Answer 20

2

so if theyre like ooh 2p subshell how many orbitals?? well it can hold 6 electrons so 3 orbitals

Question 21

the size of s orbitals increases with _______ shell number

Answer 21

increasing

so like n=3 is gonna be a bigger sphere than n=1

Question 22

p subshell has ____ orbitals and they are oriented?

Answer 22

3 orbitals

occupy x,y,z axes perpendicular to each other in a dumbell shape

Question 23

shape change of p orbitals with increasing principal quantum number?

Answer 23

longer and larger lobes

Question 24

what is spin-pair repulsion?

Answer 24

when 2 electrons spinning in the same direction (same spin) repel each other

Question 25

what is Hunds rule?

Answer 25

due to spin-pair repulsion, electrons occupy seperate orbitals before pairing up with another with opposite spin

(basically in the square thing, you fill in ^ ^ ^ before going ^v ^v ^v)

Question 26

what is the Pauli Exclusion principle?

Answer 26

an orbital can hold 2 electrons and they must have opposite spin

Question 27

how does shorthand electron configuration work

Answer 27

use the nearest preceding noble gas + rest of the config

[Ar]3d^54s^1

Question 28

transition metals fill the 4s/3d subshell first and lose electrons from the 4s/3d subshell first

Answer 28

4s !!!

Question 29

according to electronic configuration, how is the periodic table split up?

Answer 29

left grp: s block
mid (transmetals): d block
right (nm): p block
below: f block

Question 30

name the 2 exceptions to Aufbau principle

Answer 30

Cr (Chromium)
Cu (copper)

Question 31

Cr is NOT 3d4 4s2 it is?

Answer 31

3d5 4s1

Question 32

why are Cr and Cu exceptions to Aufbau principle

Answer 32

its more energetically favourable to have a full/half 3D SUBSHELL than a full 4s

Question 33

when energy is released when electron goes from n=2 to n=1, what series does it correpsond with?

Answer 33

ultraviolet

Lyman series

Question 34

what is Bohr’s model?

Answer 34

idea that electrons exist in discrete energy levels SO an EXACT amt of energy is needed to ‘jump’ an energy level

Question 35

3 limitations of Bohr’s model

Answer 35

1. assumes positions of electrons are FIXED
2. assumes energy levels are SPHERICAL in nature
3. only applicable to HYDROGEN

Question 36

what is the limit of convergence?

Answer 36

the frequency at which the spectral lines appear to meet // converge

= first ionisation energy

Question 37

frequency of radiation in emission spectrum at the limit of convergence can be used to determine the ?

Answer 37

first ionisation energy

Question 38

what is the first ionisation energy from the Lyman series?

Answer 38

UV region! limit of convergence = energy given out when electron falls from n=infinite to n=1

Question 39

what data booklet constant will you need to calculate first ionisation energy using convergence limit?

Answer 39

plancks constant!

Question 40

in the conversion between wavelength and frequency whats the unit for wavelength

Answer 40

m!

so if its nm then you gotta x10^-9

Question 41

convert J to kJ

Answer 41

divide by 1000

Question 42

2 things to rmb when calucating first ionisation energy from convergence limit

Answer 42

convert to per mole using AVOGARDOS CONSTANT

convert final units to kJ/mol (if asked for)

• all eqns in formula booklet

Question 43

4 factors affecting first ionisation energy

Answer 43

1. size of nuclear charge
2. distance of outer electrons from nucleus
3. shielding effect (inner electrons)
4. spin pair repulsion

Question 44

first ionisation energy ______ across a period and _______ decreases down a group

Answer 44

increases

decreases

(top right corner highest)

Question 45

explain the increase in ionisation energy across a period 4

Answer 45

nuclear charge incr

atomic radius decr = decr dist

shielding constant

harder to move electron = more energy needed

Question 46

dips in the trend of first ionisation energy increasing across the period name 2

Answer 46

between beryllium and boron

between nitrogen and oxygen (spin-pair repulsion)

Question 47

why is there a dip in the ioniastion energy trend between beryllium and boron

Answer 47

distance

5th beryllium electron is in 2s
BUT
5th in boron is in 2p (further) = lower

Question 48

why is there a dip in the ioniastion energy trend between nitrogen and oxygen

Answer 48

spin-pair repulsion in 2p orbital of oxygen

nitrogen has
p orbital ^ ^ ^

oxygen has
p orbital
^v ^ ^

= repulsion = easier to remove = decr first ionisation energy

Question 49

how does first ionisation energy change one period to the next + why? (dist, shielding, charge)

Answer 49

it has a LARGE DECREASE

• incr dist
• incr shielding bc new shell
• outweighing the incr nuclear charge

Question 50

why do successive ionisation energies increase

Answer 50

remove first electron = ion

more difficult to remove electron

attractive forces incr with electron decr
- decr shielding
- incr charge

also depends on electronic configuration

Question 51

big jumps in successive ionisation energies = ?

Answer 51

change of shell
(so if 2nd is hard to remove, there is 1 valence electrion)

(smaller jumps = change of subshell)