Broderick's Chapter 2 atomic structure

Question 1

What is the mass of an electron ?

Answer 1

1/2000 or 5X10^-4

Question 2

What is the mass spectrometer and how does it work ? Also define Isotope

Answer 2

used to determine which isotopes are present in the sample and the relative abundance of each one of them

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

Question 3

Why do isotopes have similar chemical properties but different physical properties ?

Answer 3

Same number of electrons - reactions only dependent on the arrangement of electrons

different masses - different speed, different boiling and melting points, different density

Question 4

Formula for the maximum number of each shell

Answer 4

2n^2

Question 5

List out the em waves from lowest frequency and discuss the trends

Answer 5

RMIVUXY (radio waves, microwaves, Infrared, Visible l ight, Ultra violet, X rays, Y rays )

So as frequency increases, energy increases from the spectrum

Wavelength decrease

Question 6

Continuous spectrum

Answer 6

consists of all colour merging into each other

Question 7

What is the electron in the lowest energy level called ? What is the electron in the highest energy level called ?

Answer 7

ground state

Excited State

Question 8

How does the visible spectrum arise ?

Answer 8

1. passage of electric discharge causes electrons to be promoted to higher energy level
2. electron in higher energy level is unstable - return to a lower energy level
3. As it returns to a lower energy, it releases a photon of light, gives out a line on the spectrum

Question 9

What gives evidence that electron in atoms only have specific energy levels ?

Answer 9

atomic emission spectra consists of line that get closer together at high energy frequency, line arise when electrons falls from higher energy to lower one. Energy emitted

Question 10

In the hydrogen emission spectrum, transition to energy level 1 is corresponds to which em wave ?

Transition to energy level 2 ?

Transition to energy level 3 ?

Answer 10

1. UV radiation
2. Visible light
3. Infrared Radiation

Question 11

Why is energy difference between level 1 and any other level is bigger than that between level 2 and other level ?

Answer 11

All transition to level 1 occur in the UV region - require highest energy

Question 12

Convergence limit

Answer 12

lines get closer together at higher frequency on the emission spectrum, electron is released from the nucleus therefore it can have any energy level

Question 13

Ionisation energy

Answer 13

minimum amount of energy required to release an electron of a gaseous atom or molecule

Question 14

Why is the hydrogen spectrum simple ?

Answer 14

1. it only contains one electron

2. atoms with more electron, the spectra would be more complicated and cannot be explained simply on the shells

Question 15

Equation for calculating energy of photon

Answer 15

E = hv

where h = plank’s constant
v = Hz or S^-1
E = J

Question 16

The frequency is related to the wavelength formula

Answer 16

C = v x lambda

c : speed of light
lambda : wavelength of light in m

Question 17

Combination for two equation for ionization energy

Answer 17

E = (h x c) / lambda

Question 18

How are sub levels ordered from smallest to largest ?

Answer 18

s < p < d < f

Question 19

Name the four processes of the mass spectrometer in order

Answer 19

V apourisation 
I onisation 
A cceleration 
D eflection 
D etection

Question 20

Explain each of the processes of the mass spectrometer

Answer 20

Vapourisation
Ionisation - molecules bombarded by electrons, the collision of electron and particles results in a positively charged ion.

Acceleration - positive ions accelerate towards negative plates at a speed dependent on their mass.

Deflection - positively charged ions are deflected by a magnetic field.
The amount ions are deflected by depends on
-the mass of the ion (lighter ions will be deflected more than heavier ones)
-the charge of the ion (ions with a greater charge than +1 are deflected more)

Detection - When an ion hits the detector, the charge is neutralised, and this generates an electrical current. This current is proportional to the abundance of the ion, these are sent to a computer for analysis.