O Level Chemistry: Periodic Table & Group Trends

31 Jan

Posted by: sean in: Chemistry Notes & Tips

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Periodic Table

(Photo by ma-kasu)

In Chemistry, Periodic Table has long been regarded by students, educators and chemists as the “Bible” of Chemistry.

We need to have a good grasp of the General Features & the important Patterns (Group Trends) in order to appreciate many other topics and to score in exams.

General Features of Periodic Table:

Elements are arranged in the order of increasing proton / atomic number
A horizontal row of elements is called a Period
A vertical column of elements is called a Group
Elements are further divided into Metals & Non-Metals (Green line in the above image)
Electronic configurations, period number & group number are related to each other

Example:

Sodium (Na) is located in Group I and Period 3 of the Periodic Table.

Electronic Configurations of Sodium (Na) atom is 2.8.1

This shows that Na atom has only 1 valence (outermost shell) electrons and all the electrons occupies 3 shells (2 electrons occupy innermost shell, 8 electrons occupy 2nd shell and 1 electrons located in the outermost shell).

The above highlight a very important feature of Periodic Table:

Period Number = Number of electron shells

Group Number = Number of outermost electrons

Got it? Let me know if you need any clarifications.

Let’s try out some basic exam-based questions for a start:

Quick Check 1:
How many Groups & Periods are there in the Periodic Table?
A) 9 and 6 respectively
B) 9 and 7 respectively
C) 8 and 6 respectively
D) 8 and 7 respectively

Quick Check 2:
How many elements are found in the 1st Period of the Periodic Table?
A) 8
B) 6
C) 2
D) 1

Try it out!

PS: Leave your answers in the comments section below. We will get back to you with our suggested answer too!

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9 Responses

Kerk Yan Juin
02|Feb|2010 1

Quick Check 1:
There are 8 Groups(Vertical Column) and 7 Periods(Horizontal Column)
in the Periodic Table.
Hence the answer is D.

Quick Check 2:
There are 6 elements found in the 1st Period(Horizontal Column)
of the Periodic Table.
Hence, the answer is B.

Reply
sean Reply:
May 5th, 2010 at 11:03 pm
Hi Kerk Yan Juin,

Response to your suggested answers.

Quick Check 1:
- Spot on. Answer is indeed D. Well Done!

Quick Check 2:
- Common error! You had fall into the trap set by many examiners and teachers.
- Look again at 1st Period which is the Horizontal Row – there are only H and He there.

As such, answer should be C.

To Your Academic Success in Chemistry,
Sean Chua
Master Trainer & Author

Reply
O Level Chemistry: Periodic Table & Group Trends by SimpleChemConcepts
04|Feb|2010 2

[...] the previous blogpost, we have discussed about the General Features of the Periodic [...]
Kim
08|Feb|2010 3

Don’t the metals count? I see 18 vertical columns, puzzled by the lack of an explanation for that.

Plus the first period has only two elements, hydrogen and helium. So the answer is C

Reply
sean Reply:
May 5th, 2010 at 11:05 pm
Hi Kim,

The rectangular block of metal elements between Group II and III is known as Transition Metals and NO group number are assigned to them. As such, there should only be 8 Groups in the Periodic Table.

For Quick Check 2, you are absolutely right. Well Done.

To Your Academic Success in Chemistry,
Sean Chua
Master Trainer & Author

Reply
nton akonjom bassey
23|Feb|2010 4

i wish to participate in chemistry vote

Reply
sean Reply:
May 5th, 2010 at 10:58 pm
You can do so by checking the topic you think is most challenging and then click “vote”.

Rgds,
Sean Chua

Reply
farhan
15|Apr|2010 5

how to find group and period for a element having more than 8 electrons in its outermost shell?

Reply
sean Reply:
May 5th, 2010 at 11:08 pm
Hi farhan,

Discussions on SimpleChemConcepts.com is based on Basic Chemistry Syllabus (such as GCE-O Levels Chemistry).

For elements that can hold more than 8 electrons in their outermost shell, they belong to Advanced Level Chemistry (such as GCE-A Levels Chemistry). Do visit the new webiste for advanced level chemistry students : http://www.ALevelH2Chemistry.com to find more discussions.

To Your Academic Success in Chemistry,
Sean Chua
Master Trainer & Author

Reply