periodic table of elements allowed?

[steveysmith54]

will we have one for the test?

 

[NexusMD]

i believe they provide a basic one.

 

[tckc]

i took the october exam and got no periodic table...so unless they've changed their rules...i would assume you'll have none

 

[steveysmith54]

some of the questions in the books that i have are just imposible to answer if one doesn't know the atomic numbers of elements when they ask for electron configuration etc.

 

[dtp384]

they'll provide u with all the necessary info within the question

 

[steveysmith54]

#235 from the practice pcat exam that someone posted

235. What is the ground state electronic configuration
of Lu?
A. [Xe] 6s24f145d1
B. [Xe] 6s26f146d1
C. [Xe] 6s26d16f14
D. [Xe]6s25d14f14

Can u do this problem w/ out a periodic table?????

 

[al_rx]

Yes, you can answer this question w/o a periodic table (in fact, a periodic table wouldn't help much with this). This question is asking if you have a basic understanding of the order in which electron shells are filled, and how many electrons occupy each atomic orbital.

So, in this example, you can immediately eliminate answers C and D because they both have d-orbitals with greater than 10 electrons (6d16, 5d14) - which is impossible. Then, for the remaining two answers, we can tell that answer B can't be correct as it states that the 6f orbitals come after the 6s orbital which is wrong (orbitals for a given electron shell go in the order of s,p,d,f). This leaves the only possible answer to be A.

Hope that helps.

 

[dtp384]

thanks al

the pcat isnt simply about regurgitating information...its also about using logic to answer the questions. if they dont provide u with some info, the question can be answered without it...u just have to figure it out.

good luck to everyone for this saturday 👍