A Tour of the Periodic Table of the Elements, Part 1

Posted on 10 August 2015 by RobertLovesPi

Periodic-Table-of-Elements 1st one with alkali metal and such

(click to enlarge)

In this, and the some upcoming posts, I’ll be showing you various collections of elements on the horizontally-extended version of the periodic table — one that includes the f-block elements in their proper place, rather than relegating them to two separate rows below the other elements. (I’m also suggesting the purple letters A – N for the usually-unrecognized groups in the f-block, and keeping the group numbers 1-18, with which many are familiar, for other groups).

For this first post, I’ll start with some sets of elements which are familiar to most who have studied the subject, plus some others which are much less well-known.

Light blue — the alkali metals.
Black background with red symbol and atomic number — hydrogen, which is definitely not an alkali metal, despite it sharing group 1 with them.
Dark blue — the alkaline-earth metals.
Dark yellow — the lanthanides.
Orange — these two elements are included with the lanthanides in some sources, and with the transition metals in others.
Bright pink — the actinides.
Light pink — these two elements are included with the actinides is some sources, and with the transition metals in others.
Red — the transition metals, also known as the transition elements, and d-block elements.
Light purple — group 13 is often called the “boron group,” but it also goes by other names, such as the “icosagens” and the “triels.”
Dark purple — group 14 is often called the “carbon group,” but it also goes by other names, such as “tetragens” and “crystallogens.” In semiconductor physics, these elements are referred to as group IV elements.
Dark green — group 15 elements are referred to as the pnictogens, or nitrogen-group elements.
Bright yellow — bright yellow is used here for the chalcogens, also known as the group 16 elements, or oxygen-group elements.
Light green — the halogens.
Gray — the noble gases.

The “Destabilized” Element, Bismuth, Plus Others Which May Join It Soon

Posted on 21 September 2014 by RobertLovesPi

There is a chemical element, bismuth, which many people — even chemists — think has at least one stable isotope. However, the truth, discovered in 2003 (but still not well-known), is that it has no stable isotopes, but does have one with an extremely long half-life — so long that it, and other isotopes with similarly-long half-lives, are often deemed “effectively stable.” Bismuth is shown in green on the table, and its “effectively stable” isotope, bismuth-209, has a half-life of at least 1.9 x 10¹⁹years. For comparison, it has “only” been ~1.38 x 10¹⁰years since the Big Bang. Bismuth-209’s half-life is, therefore, over a billion times longer than the total amount of time which has existed, so far.

In addition, the yellow boxes indicate elements which have only radioactive and “observationally stable” isotopes. “Observationally stable” means that radioactivity (in some cases, even the spontaneous-fission variety), with an extremely long half-life, is predicted, or at least thought to be possible, but no actual decay has yet been observed — so the yellow elements’ perhaps-stable, perhaps-not isotopes are “on watch.” The red boxes, by contrast, are for elements which have been long-known to have no stable isotopes.

None of this takes into consideration the unresolved issue of hypothesized long-term proton decay. If protons turn out to be unstable, all atoms likely are as well, unless simply having them exist in atoms somehow stabilizes them, as is the case for neutrons, which decay in isolation, but do not in stable nuclei. This is an area of uncertainty — another way of saying that this is something which needs further study.

My Students’ Painting of the Periodic Table of the Elements

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My Students' Painting of the Periodic Table of the Elements

This is my last year teaching at my current school — I’ll be transferring to another school in the same district in the Fall. To create a farewell gift to the school where I have taught for the last three years, I brought a lot of paint and other art supplies from home, bought more when they ran out, and let my students (who are enrolled in Chemistry and Physical Science) paint a large painting of the periodic table on two large wooden boards, each measuring 4′ by 6′. In the Fall, the plan is for the painting to be mounted on the wall of the science wing of my current school, in a location to be chosen by my current department chair, a personal friend of mine.

I think my students did a very good job — better than this picture I took with my cell phone reveals, just due to camera-quality. I am proud of them.