IS THE PERIODIC TABLE A KID OR A TEENAGER?

[Gian]

The BBC's GCSE Chemistry page says there are eight 8 groups in the Periodic Table; 1-7, plus 0 (noble gases?) But there are ten columns between 2 and 3 with no number:
https://www.bbc.co.uk/bitesize/articles/zptfn9q#zkn27yc


However, other versions of the Table like this one from the The Royal Society of Chemistry show 18, eighteen groups. What's going on??
https://www.rsc.org/periodic-table

I should emphasise that age 32 I'm pre-GCSE level so my science age is about 12½  please keep answers as simple as possible

Cheerz

GCSE GIAN😊XXX

science age 12½

[studiot]

The Periodic Table

 

Hmm  -  An interesting place to start your study of chemical bonding.

 

To have any sort of periodic table at all it was necessary to identify enough different 'elements' to arrange.
This was achieved between the late 17 hundreds and the early 18 hundreds.

At that time there was no such idea as 'atomic number' (ask if you need to know what this is).
Known elements were arranged by atomic weight  - although this was not as easy as it seemed and the first Internation Conference in Chemistryheld in 1860 was intended to produce proper definitive definitions for 'atom',  'molecule', 'radical'  and 'equivalent' but ended without achieving this.

However some of the participants, including Mendeleyev,  left with the the suggestion by Cannizzaro to abandon the weight order.

Chemists up to that time has followed the classical mathematical connection between music (yes music in the guise of harmonic scales) and science.

There was Dobereiner's triads or rule of 3

• Triad 1. Lithium: Sodium: Potassium: ...
• Triad 2. Calcium: Strontium: Barium: ...
• Triad 3. Chlorine: Bromine: Iodine: ...
• Triad 4. Sulfur: Selenium: Tellurium: ...
• Triad 5. Iron: Cobalt: Nickel:

 

and Newlands rule of rule of octaves

which led to the first 'periodic table'

 

 

https://byjus.com/chemistry/newlands-law-octaves/

https://www.simply.science/images/content/chemistry/structure_of_matter/dev_of_periodic_table/conceptmap/Newlands_Law.html

 

Following the switch to 'atomic number'  Mendeleyev was able to place the 63 known elements in their proper position in a table.

But they did not know why or about the other 55 naturally occurring elements ( or the radioactive ones).

 

Since that time there have been many attempts to extend the table and it has been found necesary to split the original 8 columns to incorporate new subcolumns.
Different arrangements do this differently.

 

Have you ever been to the Science Museum ?

It is really worth a visit if you can get there, here is their offering on the subject.

Quote

The periodic table is one of the most iconic images in science, a guide to the chemistry of our world. But it's only one among many visual ways to classify the elements.

There are thousands of alternative periodic tables or systems, some predating the invention of the now-standard version you might know from the school chemistry lab.  

https://www.sciencemuseum.org.uk/objects-and-stories/chemistry/developing-modern-periodic-table-spirals-stars

 

OK so where are we today ?

 

Well we are moving away from periodic tables of chemical properties alone, bearing in mind radioactivity and what we now know about the structure of the atom.

A new term 'nuclide' has entered the scene and the 'table' often now takes the form of a plot  N (the number of neutrons) against Z (the number of protons)

This is known as a Segre Chart

 

https://www.radiologycafe.com/frcr-physics-notes/basic-science/atomic-structure/

https://en.wikipedia.org/wiki/Table_of_nuclides

[KJW]

This may help:

https://en.wikipedia.org/wiki/Periodic_table

 

[Sensei]

On 1/11/2025 at 6:28 PM, Gian said:

The BBC's GCSE Chemistry page says there are eight 8 groups in the Periodic Table; 1-7, plus 0 (noble gases?) But there are ten columns between 2 and 3 with no number:
https://www.bbc.co.uk/bitesize/articles/zptfn9q#zkn27yc

Elements with similar configuration of valence electrons (i.e., outermost) have similar physical and/or chemical properties, so for convenience they are grouped into columns on the Mendeleev periodic table and other periodic tables from the past.

On 1/11/2025 at 6:28 PM, Gian said:

But there are ten columns between 2 and 3 with no number:
https://www.bbc.co.uk/bitesize/articles/zptfn9q#zkn27yc

From Scandium to Zinc?

You need to look at their electron configuration. It can be found on the right side of the Wikipedia page of the element in question. f.e.

You see "Electron configuration [Ar] 3d¹ 4s²" and "Electrons per shell 2, 8, 9, 2"

It means that s-subshell is filled the last (4>3).

d-subshell electron 3d¹ is unpaired, so it is valence electron as well, so Scandium compounds will often have form Sc2O3 ScCl3 etc.

https://en.wikipedia.org/wiki/Electron_shell

[Sensei]

On 1/11/2025 at 6:28 PM, Gian said:

But there are ten columns between 2 and 3 with no number:

Note that Scandium is currently classified as a group 3 element.

https://en.wikipedia.org/wiki/Group_3_element

Quote

For the other group formerly named Group III (boron group), see Group 13 element.

https://en.wikipedia.org/wiki/Boron_group

 

[exchemist]

On 1/11/2025 at 5:28 PM, Gian said:

The BBC's GCSE Chemistry page says there are eight 8 groups in the Periodic Table; 1-7, plus 0 (noble gases?) But there are ten columns between 2 and 3 with no number:
https://www.bbc.co.uk/bitesize/articles/zptfn9q#zkn27yc


However, other versions of the Table like this one from the The Royal Society of Chemistry show 18, eighteen groups. What's going on??
https://www.rsc.org/periodic-table

I should emphasise that age 32 I'm pre-GCSE level so my science age is about 12½  please keep answers as simple as possible

Cheerz

GCSE GIAN😊XXX

science age 12½

Yes it can be confusing. Notice these groups are described as Main Groups, and also that the block in between (often called the d-block) is described as being for the Transition Metals. The "transition" metals were historically viewed as being in the transition from the simpler rules of chemical behaviour of the light elements of the 1st 3 rows to the more complex behaviour of the heavier ones from the 4th row onward. (As with so many things in science, history has a lot to do with how things end up being named.)   

Nowadays, it is really better to speak of the s-block, for the 1st 2 main groups, the p-block for groups 3-7 and 0, the d-block for the transition metals (and the f-block for the so-called lanthanides and actinides that are usually represented below the d-block.) But over the years there have been many different ways to display the table and also a variety of different numbering systems and naming conventions. So inevitably you will come across a few different ones in your reading. Just keep the shape in your mind: 2 columns of s-block metals on the left, 6 columns of p-block elements on the right, with the metal/non-metal diagonal running obliquely through them like a staircase, and the d- and f- block metals in the middle. 

The reason for the rather ungainly shape of the table is to do with the order in which electrons build up* in layers within the atom, as one moves through the table from lighter elements to heavier ones. Remember that It is the outer electrons (called the "valence" electrons) that are responsible for the chemical behaviour of the elements. The shape of the outermost layer, and how strongly or weakly bound the electrons in it are, is what determines how the element will behave in chemical reactions. 

 

 

* from the German Aufbauprinzip or building up principle, which explains how the behaviour of the outermost electrons is determined by quantum theory. You will get to that in due course. It's rather cool.  

Edited 20 hours ago by exchemist

[studiot]

Just now, exchemist said:

Yes it can be confusing. Notice these groups are described as Main Groups, and also that the block in between (often called the d-block) is described as being for the Transition Metals.

etc

Good summary  +1