Today, we are going to cover another common mistakes made by 90% of the students year-after-year, that has been observed in the recent Chemistry Revision Workshop as well as similarly documented in the “Up Your Chemistry Grades Now!”.
The following question test students on the familiarisation of Periodic Table and how elements are arranged.
Question:
Many of the students would casually and quickly select the answers as (A), which is the incorrect answer.
The question shows diagrams/charts which aims to psychologically affect us to choose the wrong answer. Many students chose answer (A) because they learned in school and books before that “Elements in the Periodic Table are arranged in the order of increasing atomic number, which corresponds to the increasing proton number”! There is nothing wrong with the definition above.
The only problem is that students did not spend some time understanding the charts given:
It is “number of outer shell electrons” plotted against “proton number” for 1st 12 elements in the Periodic Table.
If you realised the axes of the charts, then you will work out your answer to be (B) instead.
If you still do not get the answer as (B), the following Periodic Table showing Electronic Configurations will certainly help you in your understanding.
(click image to see clearer)
PS: Let me know if you need more assistance and clarification on this question. Leave me a comment right below.
Stay Tuned to Part 3 of the ?Common Errors in Chemistry Concepts made by Students? mini series.
Until then….
Hi Kwee,
Good explanations! You seemed to have a good grasp of “Periodic Table” and “Atomic Structure”.
Congrats!
PS: look forward to more of your participation, as this is the best form of learning methodology
Cheers,
Sean Chua
Master Trainer & Author
WINNERS Education Group
?Experience Learning with A Difference?
Ans is B.
Max number of valence electrons is 2 for the 1st period, ONLY. 8 for the rest. Proton number will keep increasing, but the valence electron number will not. i.e. from proton number 1 to 12, the configuration is (1; 2; 2,1; 2,2; 2,3 … 2,8; 2,8,1; 2,8,2) meaning, it will go from 1 to 2, back to 1, go up to 8, go back to 1 and increase by 1 again. Hence B is the answer.