Topic 2/12

Question 1

In emission spectrum, where do lines converge?

Answer 1

At higher frequencies

Question 2

Br-79 and Br81 have AR = 79.9

Answer 2

Let Br-79 = x and Br-81 = 1-x because the x’s equal to 100%

Question 3

How to calciluate the first ionisation energy of hydrogen?

Answer 3

E = hv
Where h is plank’s constant and V is the frequency. Then you multiply by avogadro’s constant to find it for one mole of hydrogen. Then divide by 1000 to convert to kJ

Question 4

Is ionisation energy endothermic or exothermic

Answer 4

Endothermic becuase energy must be added to overcome electrostatic attraction

Question 5

How are emission spectrum produced

Answer 5

Photoons emitted from atoms as excited electrons return to lower energy level

Question 6

Exceptions to electron configuraton

Answer 6

Chromium and copper, d orbital fills up first rather than s

Question 7

Which electron transition emits energy of the longest wavelength?

Answer 7

Electromagnetic spectrum, longer wavelength n=3 because IR, then visible, than UV

Question 8

Why do most magnesium compounds in schoo llab show traces of yellow in the flame?

Answer 8

Contamination of other compounds

Question 9

What is equivalent to high energy

Answer 9

High frequency

Question 10

équation for energy of photon

Answer 10

E = hc/lamda

Question 11

Describe the emission spectrum of hydrogen?

Answer 11

Series of lines at certain frequencies that converge at higher frequencies

Question 12

How to determine the wavelength of UV light abosbred by O2

Bond enthalpy 489kJ/mol

Answer 12

E = 498000J/6.02x10^23
lambda = Planks x C/E

Question 13

What can be determined from the frequency of the convergence limit?

Answer 13

Ionization energy

Question 14

Frequency of photon for first ionization of copper

Answer 14

E = first ionization of copper/avogadros constant
E = hv

Question 15

12.2 Equations

Answer 15

E = hv
E = hc/lambda
c = v(labda)

Question 16

Maximum number of electrons in energy shells 1-4

Answer 16

1 - 2
2 - 8
3 - 18
4 - 32 (4f 14)

Question 17

Why does first electron affinity have positive value for nitrogen?

Answer 17

Greater repulsion when electrons occupy the same orbital (since electron added to what is already 2p3

Question 18

Why do noble gases have largest first ionization energy and largest positive first electron affinity?

Answer 18

~ Higher nuclear charge, smaller radius
~ Adding to new energy level