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## Chapter 2: Electronic Structure and the Periodic Table

### Chapter 2: Electronic Structure and the Periodic Table

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I don't understand the values in Quantum Numbers, can anyone explain in bigger detail please?
jennifer.h5402

Posts: 8
Joined: Tue Mar 08, 2011 9:35 pm

There are no units for quantum numbers (per se). For example, the first quantum number is simply counting the number of orbitals. Imagine counting the rings around Saturn.

Similarly, the 4th quantum number can be positive if the electron is rotating in one direction (imagine a ball spinning on the finger of a basketball player) and negative if spinning in the opposite direction.

If you are preparing for the GAMSAT on March 26, you should not be concerned with this topic and instead all your energy should be focused on the 4 ACER practice booklets and if you have done that already then the GS practice tests online.

If you are not sitting the upcoming GAMSAT, then watch the videos (Physics and General Chemistry) on The Atom so you can get a good overview of the topic. You don't need to memorize any details on this topic for the GAMSAT.
goldstanda3269

Posts: 1673
Joined: Wed Aug 25, 2010 10:59 pm

Thank you, I appreciate your reply. I am taking the UK Gamsat in september.

I also appreciate that I dont have to memorise this topic! I think I was struggling with why the units, ie, why L could be 0,1,2...n-1. I understand 0 electrons, 1 electron, 2 electrons, but how do we get to n-1? minus an electron?

Also, Ml could be +/- l....+/- 1,0 I don't understand these figures and why they are what they are. Why is the charge, magnetic motion either +/- l....+/-1, 0 etc?

The Ms, does the -1/2 mean anti-clockwise and +1/1 mean clockwise?

many thanks if you can shed any light on this for me![/code]
jennifer.h5402

Posts: 8
Joined: Tue Mar 08, 2011 9:35 pm

I think I was struggling with why the units, ie, why L could be 0,1,2...n-1. I understand 0 electrons, 1 electron, 2 electrons, but how do we get to n-1? minus an electron?

Also, Ml could be +/- l....+/- 1,0 I don't understand these figures and why they are what they are. Why is the charge, magnetic motion either +/- l....+/-1, 0 etc?

There is a complex equation beyond the GAMSAT called Shroedinger's equation. There are 4 solutions to that equation which are more complex than normal algebra. These 4 solutions are called the quantum numbers. The quantum numbers have no units. None of the 4 quantum numbers are counting electrons.

To truly answer all your questions would require you to learn physics a few years beyond the Grade 12 level required for this exam.

The Ms, does the -1/2 mean anti-clockwise and +1/1 mean clockwise?

The following would never be asked on a GAMSAT unless the information was clearly presented in the passage:
ms = +1/2 for clockwise spin.
ms = -1/2 for anti-clockwise spin.

Have you seen the videos on this topic?
goldstanda3269

Posts: 1673
Joined: Wed Aug 25, 2010 10:59 pm

I have seen the videos, both online & on DVD.
For the Gamsat exam, what is it specifically that I need to know about these numbers?

Also, I find it difficult working from the textbook as I have very basic science knowledge. I find the DVDs more clearer in explanation. However I know that the DVDs are designed for the MCAT. What would you recommend to work from? The textbook and refer to the DVD, or vice versa? Or even doing the exams first and looking up what I don't understand via Textbook & DVD?

Many thanks
jennifer.h5402

Posts: 8
Joined: Tue Mar 08, 2011 9:35 pm

Good questions.

First some perspective: the variation in academic backgrounds for the GAMSAT is huge.

Some students may have poor English skills but they have advanced degrees in the sciences: these students are aiming for a near perfect Section 3 score. Some students may be strong in the Humanities and Social Sciences but they are learning the some of the sciences for the first time and only need an "acceptable" Section 3 score in order to get a position in medical school.

The Gold Standard GAMSAT textbook was written for both students. It has the depth so that even the student with the advanced degree will say that everything was covered. However, for the student just learning or reviewing after many years, the content can be scaled down so that you can achieve your personal goal. Unlike any exam you may have taken, it is possible to get 1/3 of the test questions wrong in a section and yet achieve a great overall score.

So how do you successfully manage your learning without falling in the trap (as a student with a non science background) of chasing every little detail described in the book?

1) Consider the Gold Standard as a course. The lectures (the videos) are meant to explain the most frequently tested concepts and strategies. In fact, if you completely understand the videos, you have covered 80% of the material for Section 3 (which is probably all you need). But like any course, the teacher will say, if you want the details or if you want to score 100% then refer to the book.

2) So then what it the book for? The intro chapters that describe the exam and strategies, the chapters about Section 1 and Section 2 with the exercises, one read through the science chapters (only once) to get a sense of the material but guided by the first page of each chapter to avoid getting lost in details, the little math review in the Appendix and finally, the full length pull out exam with worked solutions online.

3) But how do you know when you are looking at the videos that it is relevant for the GAMSAT? Well, you can always ask us. Also, you have the first page of each chapter in the book. A good example is that the videos discuss hormones in a lot of detail and you might wonder if you need to memorize the specifics. So you just look at the chapter in the book that discusses hormones and you will see that they are not in the Memorize column. Same with physics equations: we put an equation list online (go to the home page of www.gamsat-prep.com and click GAMSAT Advice in the top Menu) so that will guide you as you watch the videos as well.

4) After you read a chapter, you can always watch the chapter commentaries online (in the Lessons section) and then do a few of the chapter review questions online. This will also keep you on track. You will see that they will never ask you: what is the 3rd quantum number or some such thing.

5) And supplements to help you encode some of the information: looking at the Physics equation list regularly, flashcards, listen to mp3s or create your own using your high density notes.

There is alot to study and alot to learn. However, after all of the above, if you find yourself going into textbooks for information then it is likely that you are chasing unnecessary details.

I hope that helps.
goldstanda3269

Posts: 1673
Joined: Wed Aug 25, 2010 10:59 pm

### Re: Chapter 2: Electronic Structure and the Periodic Table

The atoms are neutral so that means that the number of electrons equals the number of protons. Of course the number of protons is equal to the atomic number. So because the superscripts are equal to the number of electrons, we just have to add the superscripts, get a number, check that number in the periodic table (from your book, for example) to see which one signifies a group 2 element.

Total number of electrons:

A) 1s2, 2s3 = 5 = Boron
B) 1s2 = 2 = Helium
C) 1s2, 2s2, 2p6, 3s2 = 12 = Magnesium which is in group II
D)
E) 1s2, 2s2, 2p2 = 6 = Carbon
goldstanda3269

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Joined: Wed Aug 25, 2010 10:59 pm

### Re: Chapter 2: Electronic Structure and the Periodic Table

CHM-21.
Chapter 2.3
Section (i) bottom left of the page.

"the row or period number gives the "n" of the valence electron of any given element of the period."

Isn't this the Group? Moving down the group they all have the same valence electron number.

After confusing myself for 10 minutes I understand now you are referring to the n quantum number, but without clarification this could easily be assumed to be n (number of ) as in other mathematical equations. This would imply what the Group actually does so is confusing.
luhogarth6245

Posts: 14
Joined: Fri Jan 30, 2015 2:00 am

### Re: Chapter 2: Electronic Structure and the Periodic Table

The generic 'n' as a number would never be used when referring to the periodic table specifically because of the importance of the quantum number n in this context. It would be like using the capital letter F for something other than force while discussing Newton's 2nd Law.
goldstanda3269

Posts: 1673
Joined: Wed Aug 25, 2010 10:59 pm

### a question about (3) in Q& A

"3) Which of the following is a characteristic of ionic bond formation?

A) It results from the interaction of metals from the left side of the periodic table with nonmetals from the right side of the periodic table.
B) It occurs between two ions of very similar electronegativity.
C) It results from the sharing of electrons between two atoms.
D) It has stronger bond energy than a covalent bond.

Your choice: A Correct choice: A"

I think D) is also correct. What do you think?
li.zhang96890

Posts: 36
Joined: Tue Aug 18, 2015 9:19 pm

### Re: Chapter 2: Electronic Structure and the Periodic Table

Yes, you are correct, that was a typo which will be corrected on Monday.

For answer choice D, "stronger" should state "lower/weaker" to create an incorrect answer choice.
goldstanda3269

Posts: 1673
Joined: Wed Aug 25, 2010 10:59 pm

### Re: Chapter 2: Electronic Structure and the Periodic Table

Hi,

Quick question- In how much detail are we expected to understand about the transition elements? e.g. should we know about half-filled and filled d orbitals?

Thank you

Lavi
Lavi

Posts: 62
Joined: Sun Aug 16, 2015 8:00 pm

### Re: Chapter 2: Electronic Structure and the Periodic Table

Lavi wrote: ... In how much detail are we expected to understand about the transition elements? e.g. should we know about half-filled and filled d orbitals?

No detail is required for GAMSAT, it would not even be assumed knowledge "about half-filled and filled d orbitals". To be clear, if those issues (or even colour changes among transition elements) were the source of a question, it would be preceded by a passage where the answer could be deduced.

The earlier that you work through ACER's Red Booklet (entitled "GAMSAT Practice Questions"), the better it will be since you will likely avoid focusing on memorisation for this reason-based exam. You may also want to attend our upcoming free webinar: https://www.facebook.com/events/577904395702663/
goldstanda3269

Posts: 1673
Joined: Wed Aug 25, 2010 10:59 pm

### Re: Chapter 2: Electronic Structure and the Periodic Table

Thank you! I'll definitely be attending the webinar
Lavi

Posts: 62
Joined: Sun Aug 16, 2015 8:00 pm

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