Imperial College London

Henry Rzepa

The element **silicon** best represents the digital era of the mid 20th
century to the present; without its crystalline form, there would be no
computers (or this blog). Although it was first prepared in pure
amorphous (powder) form around
1823\[cite\]http://doi.org/10.1021/ed009p1386\[/cite\] by Berzelius, it
was not until 1854 that Henri Sainte-Claire Deville made it in
crystalline form, using metallic aluminium to isolate it. He described
it \[cite\]http://doi.org/10.1021/ed009p1386\[/cite\] as having a
"metallic luster".

Well, an actual sample of his silicon has survived since he prepared it
in 1854,^‡ ^and so this tiny crystal could reasonably be argued to
constitute the origin of the modern computer hardware industry.

![Silicon](http://www.ch.imperial.ac.uk/rzepa/blog/wp-content/uploads/2013/10/Silicon.jpg){.aligncenter
.wp-image-11494 loading="lazy" decoding="async" width="461"
height="303"}

It is worth juxtaposing this on a modern sample of the element (below).
There is indeed a metallic luster (Deville's sample is about 2mm in
size, did I imagine it too having a luster?). Oh, the artist in me came
out when I photographed the below. The red tinge is because I
illuminated the crystals with light from a neon tube (an original sample
does still exist at [University College
London](http://www.ucl.ac.uk/chemistry/history/chemical_history/slides/neon){target="_blank"
rel="noopener"}, not more than a few km from where I write this blog).

![](https://www.ch.ic.ac.uk/rzepa/blog/wp-content/uploads/2013/10/IMG_2263-872x1024.jpeg){.aligncenter
.size-large .wp-image-25916 loading="lazy" decoding="async" width="450"
height="528"
srcset="https://www.ch.ic.ac.uk/rzepa/blog/wp-content/uploads/2013/10/IMG_2263-872x1024.jpeg 872w, https://www.ch.ic.ac.uk/rzepa/blog/wp-content/uploads/2013/10/IMG_2263-255x300.jpeg 255w, https://www.ch.ic.ac.uk/rzepa/blog/wp-content/uploads/2013/10/IMG_2263-768x902.jpeg 768w, https://www.ch.ic.ac.uk/rzepa/blog/wp-content/uploads/2013/10/IMG_2263.jpeg 1090w"
sizes="(max-width: 450px) 100vw, 450px"}

![Silicon1](http://www.ch.imperial.ac.uk/rzepa/blog/wp-content/uploads/2013/10/Silicon1.jpg){.aligncenter
.wp-image-11496 loading="lazy" decoding="async" width="377"
height="232"}

And your powers of observation do not have to be finely honed to spot
another truly original elemental sample above the silicon. This one is
even older, dating (as the caption says) back to 1826 and its discovery
in that year by Antoine Balard.^‡^

Original element samples, by definition, are both finite and rare. The
Royal Institution in London (again just down the road from where I am)
has perhaps the largest collection of [mainstream elements (groups I and
II) prepared by
Davy](http://www.rigb.org/our-history/iconic-objects/iconic-objects-list/davy-samples){target="_blank"
rel="noopener"} there,^†^ but there is no catalogue I am aware of which
lists all the original elemental samples still existing and their
location in the world. I suspect the majority are no longer around. But
I would welcome anyone who knows of the location of such to post a
comment, perchance even a photo, here.

------------------------------------------------------------------------

^‡^The provenance is impeccable. ^†^ Potassium (1807), sodium, barium,
calcium, magnesium, strontium and boron. [See
here](http://periodictable.com/Elements/014/index.html){target="_blank"
rel="noopener"} for photos of modern samples.

------------------------------------------------------------------------

![all](http://www.ch.imperial.ac.uk/rzepa/blog/wp-content/uploads/2013/10/all.jpg){.aligncenter
.wp-image-11504 loading="lazy" decoding="async" width="289"
height="304"}

::: {.wp_orcid_field}
[https://orcid.org/0000-0002-8635-8390](https://orcid.org/0000-0002-8635-8390){target="_blank"
rel="author"}
:::


The element
<strong>
 silicon
</strong>
best represents the digital era of the mid 20th century to the present;

The world ash tree of the computer hardware industry… crystalline silicon from 1854.

In his famous lecture in 1959, C. P. Snow
[wrote](breakdown%20of%20communication%20between%20the%20%22two%20cultures%22%20of%20modern%20society%20—%20the%20sciences%20and%20the%20humanities%20){target="_blank"}
about the breakdown in communications between the "two cultures" of
modern society --- the sciences and the humanities (arts). That was
then. This is now, and the occasion of my visit to a spectacular "city
of arts and sciences complex" in Europe. An un-missable exhibit
representing science and life was the 15m high model of DNA. Now to be
fair this is styled an artist's impression, and one presumes that an
artist is allowed license. But how much license? And at how much expense
to the science? And is there a counterbalance to the art where the
science is fastidiously (but artistically) preserved?

![Artistic impression of
DNA.](http://www.cac.es/digitalAssets/152388_adn.jpg){decoding="async"}

Let us start from the scientific end of this story, and try a mapping
between the two representations. Below is a chemical diagram of one
strand of the DNA duplex, showing two cytosines (the single 6-ring base)
and two guanines (the 5+6 ring base) joined by a 5-ring ribofuranose to
phosphates.

::: {#attachment_4690 .wp-caption .aligncenter style="width: 347px"}
![](http://www.ch.imperial.ac.uk/rzepa/blog/wp-content/uploads/2011/08/CGCG.jpg "CGCG"){.size-full
.wp-image-4690 loading="lazy" decoding="async"
aria-describedby="caption-attachment-4690"
onclick="jmolInitialize('../Jmol/',true);jmolSetAppletColor('yellow');jmolApplet([600,600],'load wp-content/uploads/2010/12/1ZNA-H.mol2;');"
width="337" height="259"
srcset="https://www.ch.ic.ac.uk/rzepa/blog/wp-content/uploads/2011/08/CGCG.jpg 337w, https://www.ch.ic.ac.uk/rzepa/blog/wp-content/uploads/2011/08/CGCG-300x230.jpg 300w"
sizes="(max-width: 337px) 100vw, 337px"}

A scientific interpretation of DNA. Click for 3D model (of left handed
duplex DNA!)
:::

The artist has mapped the phosphates to the blue spheres and is clearly
taking the license of not showing all the atoms (and in particular the
other heteroatoms, such as O and N). That is schematic and designed not
to overwhelm. I am more or less still happy (although the missing
carbonyls are strange). Next, the phosphates are linked to the ribose.
If you look carefully you might spot that the link is built to the
centre of a C-C bond (I am starting to get slightly worried now). You
can also clearly see that the links to the guanines are *via* the
8-position of that ring, rather than the 9-position. Is this due to
artistic license or the thought that it does not much matter? The pairs
of bases, famously hydrogen bonded in a complementary manner, are now
joined by a single "bond", one end of which is now again attached at a
bond mid-point. Little of the science of hydrogen bonding is preserved
with this representation!

 

One more detail. These "rungs" joining the duplex have been rotated by
90° so that the planes of the bases are parallel to the helical axis,
rather than perpendicular. How did the artist manage to construct his
model in this orientation? Well, probably because he had been given a
template similar to the (2D) structure diagram I showed above. A chemist
would immediately "see" what is implicit in that diagram, which is all
the C-H bonds. Chemists tend to miss these out, because they can be
cluttered. But the hydrogen atoms are there, and they do occupy space.
In the 3D model, they are still missing. If you imagine their positions
in that model, you will immediately spot a number of locations where two
hydrogen atoms are trying to occupy almost the same position in space!
Of course, were you to rotate the sugar-base-base-sugar rungs by 90°
this would create space for these invisible hydrogens.

So what about this breakdown in communication between the scientist and
the artist? The latter has attempted two effects. One is to remove
unnecessary detail so that one can directly go to the essentials. The
other is to "move" the various components around so that they achieve
greater "artistic effect", but with a resulting substantial loss of
scientific accuracy. I happen to believe that the model would have
looked equally attractive if these scientific liberties had not been
taken (perhaps even better!). Perhaps, as I suggest above, the artistic
interpretation should be accompanied by a scientific one, to allow the
visitor to the museum to see both? Or the communication between sculptor
and scientist improved?

Well, I console myself with the observation that at least the artist
represents a right rather than a left handed helix!

::: {.wp_orcid_field}
[https://orcid.org/0000-0002-8635-8390](https://orcid.org/0000-0002-8635-8390){target="_blank"
rel="author"}
:::


In his famous lecture in 1959, C. P. Snow wrote about the breakdown in communications between the “two cultures” of modern society — the sciences and the humanities (arts). That was then. This is now, and the occasion of my visit to a spectacular “city of arts and sciences complex” in Europe. An un-missable exhibit representing science and life was the 15m high model of DNA.

Messaggi di Rogue Scholar

The world ash tree of the computer hardware industry… crystalline silicon from 1854.

Breakdowns in communication: the two cultures