Revision:Atomic Theory - 12 - The Student Room
The Student Room

Revision:Atomic Theory - 12

TSR Wiki > Study Help > Subjects and Revision > Revision Notes > Chemistry > Atomic Theory - 12


12.1 The mass spectrometer

12.1.1

Stages of operation : vaporisation, ionisation, acceleration, deflection and detection...Substance to be tested is vaporised (by heat, absence of oxygen) then ionised by electric current. Ions are accelerated through an electric field, then deflected by a magnetic field. Ions are then detected...the angle of deflection reflects their mass to charge ratio.


12.1.2

The angle of deflection of each fragment is proportional to it's mass, and so it is possible to find the relative atomic mass of each 'spike' the height of the spike represents the frequency, therefore, the abundance can be calculated. The relative atomic mass is the average of the isotope masses times their frequencies.


12.2 Electronic structure of atoms

12.2.1

Successive electrons can be stripped from an atom until there is only the nucleus left. If the energy required to achieve this for each electron is plotted on a graph (with a log scale) against ionisation number, the 'jumps' in the required energy clearly show the main and sub energy levels.


12.2.2

n = (1, s) (2, sp) (3, spd) (4 spdf)


12.2.3

Energies of sub-shells : s < p < d < f


12.2.4

Number of orbitals at each level : s=1, p=3, d=5, f=7


12.2.5

Shapes of orbitals : s orbital is a sphere around the nucleus. p orbitals are shaped like a figure 8 (and there are 3 of them at 90 degrees around the nucleus.

1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f


12.2.6

Move diagonally down and left through each diagonal...ie 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d... Pauli's exclusion principle says that there can only be 2 electrons in each orbital (with opposite spins). Hund's rule says that each orbital should be half filled before any is completely filled (since there is less repulsion if all electrons have the same spin). Electrons will therefore fill the lowest energy levels (ie 1 then 2 and so on) with two going in each orbital, but only doubling up when all orbitals in the level are filled.


12.2.7

Systematically fill the orbitals as shown above up to Z = 56. This can be abbreviated by writing [x] where x is a noble gas.


12.2.8

The small double column on the left is the s shell being filled. The block on the left is the p shell being filled. The d block (in the middle) is (surprisingly) the d shell being filled. The bits hanging off the bottom are the f shells being filled...forget them, they never matter :)


Comments

Discussions Toggle
St Andrews Applicants 2012
started by: such_a_lady
forum: St Andrews University
replies: 1335
last post: 1 Minute Ago
Southampton BM6 2012
started by: xcoral23
forum: Medical Schools
replies: 1822
last post: 2 Minutes Ago
UCL Medicine Applicants 2012
started by: nikhil.shah
forum: Medical Schools
replies: 1310
last post: 2 Minutes Ago
The Manchester United Thread VIII
started by: Da_hopeful_1
forum: Football
replies: 7736
last post: 2 Minutes Ago
Sun, sex and suspicious parents - BBC Three
started by: T. Hereford
forum: TV
replies: 464
last post: 2 Minutes Ago
Scenes from movies that made you cry
started by: Playa10
forum: Film
replies: 62
last post: 2 Minutes Ago
Callifornia: Ban on gay marriage unconstitutional
started by: Rds_
forum: International
replies: 50
last post: 3 Minutes Ago
BBC tells its staff: don’t call Qatada extremist
started by: Time Tourist
forum: News and Current Affairs
replies: 19
last post: 3 Minutes Ago
FA say Capello resigns
started by: lazy smurf
forum: Football
replies: 378
last post: 3 Minutes Ago
What do people usually do for their 18th birthday
started by: Mr Mondai
forum: Advice on Everyday Issues
replies: 83
last post: 3 Minutes Ago
"The role of a business is to provide a service, NOT to create profit"
started by: IB_19
forum: UK Politics
replies: 137
last post: 4 Minutes Ago
Barts and The London Applicants 2012
started by: joemullally
forum: Medical Schools
replies: 3620
last post: 4 Minutes Ago
Why is IOE taking so long ???
started by: rose.151786
forum: Education and Teaching
replies: 0
last post: 4 Minutes Ago
BBC3 - Junior Doctors: Your Life In Their Hands
started by: LaRoar
forum: Medicine Community Discussion
replies: 2176
last post: 5 Minutes Ago
Alan Turing refused a formal pardon
started by: Wednesday Bass
forum: UK Politics
replies: 50
last post: 5 Minutes Ago
Oxford Graduate Application 2012/13
started by: Poincare
forum: Postgraduate
replies: 1064
last post: 6 Minutes Ago
Before buying PC please ask our advice first!
started by: AT82
forum: Technology and Computers
replies: 6762
last post: 6 Minutes Ago
ODE
started by: Brit_Miller
forum: Maths
replies: 0
last post: 6 Minutes Ago
How many number of songs do you have in your iPod?
started by: PaperBoy
forum: Music
replies: 90
last post: 6 Minutes Ago
The Ultimate 'Am I Good Enough For Medicine?' Angst Thread Mk II
started by: Hygeia
forum: Medicine
replies: 7025
last post: 6 Minutes Ago
Article Updates Toggle
Contact Us | Site Rules | Staying Safe on TSR | Advertising | Staff Blog | Essays & Coursework | Terms & Conditions | Top
Customise your TSR | Life Advice | Hobbies and Interests | Debate and Current Affairs | Study Help | University and University courses
Universities and HE Colleges | Careers, Employment and Gap Years | General Discussion

Customise your TSR