Mark Lorch

On the 150th Anniversary of the Periodic Table: What It Could’ve Looked Like

Contrary to popular belief, the periodic table didn’t actually start with Dimitri Mendeleev. Many had tinkered with arranging the elements.

The periodic table stares down from the walls of just about every chemistry lab. The credit for its creation generally goes to Dimitri Mendeleev, a Russian chemist who in 1869 wrote out the known elements (of which there were 63 at the time) on cards and then arranged them in columns and rows according to their chemical and physical properties. To celebrate the 150th anniversary of this pivotal moment in science, the UN has proclaimed 2019 to be the International year of the Periodic Table.

John Dalton’s element list Credit: Wikimedia Commons

But the periodic table didn’t actually start with Mendeleev. Many had tinkered with arranging the elements. Decades before, chemist John Dalton tried to create a table as well as some rather interesting symbols for the elements (they didn’t catch on). And just a few years before Mendeleev sat down with his deck of homemade cards, John Newlands also created a table sorting the elements by their properties.

Mendeleev’s genius was in what he left out of his table. He recognised that certain elements were missing, yet to be discovered. So where Dalton, Newlands and others had laid out what was known, Mendeleev left space for the unknown. Even more amazingly, he accurately predicted the properties of the missing elements.

Notice the question marks in his table above? For example, next to Al (aluminium) there’s space for an unknown metal. Mendeleev foretold it would have an atomic mass of 68, a density of six grams per cubic centimetre and a very low melting point. Six years later Paul Émile Lecoq de Boisbaudran, isolated gallium and sure enough it slotted right into the gap with an atomic mass of 69.7, a density of 5.9g/cm³ and a melting point so low that it becomes liquid in your hand. Mendeleev did the same for scandium, germanium and technetium (which wasn’t discovered until 1937, 30 years after his death).

At first glance Mendeleev’s table doesn’t look much like the one we are familiar with. For one thing, the modern table has a bunch of elements that Mendeleev overlooked (and failed to leave room for), most notably the noble gases (such as helium, neon, argon). And the table is oriented differently to our modern version, with elements we now place together in columns arranged in rows.

But once you give Mendeleev’s table a 90-degree turn, the similarity to the modern version becomes apparent. For example, the halogens – fluorine (F), chlorine (Cl), bromine (Br), and Iodine (I) (the J symbol in Mendeleev’s table) – all appear next to one another. Today they are arranged in the table’s 17th column (or group 17 as chemists prefer to call it).

Period of experimentation

It may seem a small leap from this to the familiar diagram but, years after Mendeleev’s publications, there was plenty of experimentation with alternative layouts for the elements. Even before the table got its permanent right-angle flip, folks suggested some weird and wonderful twists.

One particularly striking example is Heinrich Baumhauer’s spiral, published in 1870, with hydrogen at its centre and elements with increasing atomic mass spiralling outwards. The elements that fall on each of the wheel’s spokes share common properties just as those in a column (group) do so in today’s table. There was also Henry Basset’s rather odd “dumb-bell” formulation of 1892.

Nevertheless, by the beginning of the 20th century, the table had settled down into a familiar horizontal format with the strikingly modern looking version from Heinrich Werner in 1905. For the first time, the noble gases appeared in their now familiar position on the far right of the table. Werner also tried to take a leaf out of Mendeleev’s book by leaving gaps, although he rather overdid the guess work with suggestions for elements lighter than hydrogen and another sitting between hydrogen and helium (none of which exist).

Heinrich Werner’s modern incarnation.
Reprinted (adapted) with permission from Types of graphic classifications of the elements. I. Introduction and short tables, G. N. Quam, Mary Battell Quam. Copyright (1934) American Chemical Society.

Despite this rather modern looking table, there was still a bit of rearranging to be done. Particularly influential was Charles Janet’s version. He took a physicist’s approach to the table and used a newly discovered quantum theory to create a layout based on electron configurations. The resulting “left step” table is still preferred by many physicists. Interestingly, Janet also provided space for elements right up to number 120 despite only 92 being known at the time (we’re only at 118 now).

Settling on a design

The modern table is actually a direct evolution of Janet’s version. The alkali metals (the group topped by lithium) and the alkaline earth metals (topped by beryllium) got shifted from far right to the far left to create a very wide looking (long form) periodic table. The problem with this format is that it doesn’t fit nicely on a page or poster, so largely for aesthetic reasons the f-block elements are usually cut out and deposited below the main table. That’s how we arrived at the table we recognise today.

That’s not to say folks haven’t tinkered with layouts, often as an attempt to highlight correlations between elements that aren’t readily apparent in the conventional table. There are literally hundreds of variations (check out Mark Leach’s database) with spirals and 3D versions being particularly popular, not to mention more tongue-in-cheek variants.

How about my own fusion of two iconic graphics, Mendeleev’s table and Henry Beck’s London Underground map below?

Or the dizzy array of imitations that aim to give a science feel to categorising everything from beer to Disney characters, and my particular favourite “irrational nonsense”. All of which go to show how the periodic table of elements has become the iconic symbol of science.

This article is republished from The Conversation. Read the original article here.

To Loiter or Not? – The Question of Women’s Access to Public Spaces

Mobility is at the centre of feminism – and women are here to reclaim the right to roam the streets.

Gender and mobility are closely intertwined, though urban planners often forget to connect these dots and so create unequal cities through their physical infrastructure itself.

Historically, women have always been confined to the private sphere as the stereotype was that they were docile and needed protection. This was also a method to control them and restrict their movements.

For women to go outside then is more than just the act of moving out of the indoor spaces, it is about challenging the gender status-quo. Hence, the ability to expose themselves to a sphere which is outside the home and go into public spaces to attend a variety of activities on their own is an act of empowerment.

In her famous work A Wheel within a Wheel, American suffragette Frances Willard talks about the freedom she gets from riding a bicycle, and opines that mobility is primarily at the centre of feminism. The liberation that is achieved through spatial movement leads to a greater level of accomplishment, a soul-stirring sense of confidence, expanded horizons, aspirations and personal growth.

However, given the patriarchal shackles that we find ourselves bound by, the liberty of women to run wild while roaming outdoors seems to get crippled for the sake of upholding an upright moral character. A woman is often forced to abandon her love for outdoors and restrict herself to the indoor realm of household affairs.

The meaning of a ‘good’, ‘virtuous’ and ‘respectable’ girl is constantly shifting and being contested. These changes reflect the cultural progress over prescribed gender norms that requires us to keep re-defining certain behaviours. This also flows into creating or promoting an inclusive spatial movement.

Given that women’s activities in public spaces are often restricted, zoning separating land uses such as industrial, residential, commercial leads to antiquated gender roles that confine women to local private spaces.

Further, women are usually blamed for any unfortunate incidents that may occur if they fail to comply with the unwritten norms of the public spaces. Despite all the advancements in the field of science and technology, it is unfortunate that women’s safety is correlated to their confinement, whether spatially or temporally.

Looking at public toilets, it becomes obvious that they are mostly designed for men – rather than being accommodative of women’s specific needs as well. The underlying assumption may well be that fewer women go out and hence, the need is not at a substantial scale.

As Canadian professor and the first major communications theorist, Marshall McLuhan pointed out globalization is turning the world into a global village – it presents women in developing nations with massive opportunities and access to the outer world, potentially shifting bargaining power within their households and changing the choices that are made for subsequent generations.

Such an existing scenario can maybe explain the spectacular popularity of shopping malls in developing nations. On investigating beyond what appears to be a result of globalization and subsequent commercialization, malls also provide a closed confined public space for women. They often act as a source of respite for disadvantaged sections of society – like women – who are often excluded from urban public life.

Though physical barriers have always existed, it was the fear of potential unwanted interactions that limited women’s access to urban space.

The reality of the daily lives of women has not been recorded for urban planning processes. To bring about a positive and sustainable change, the question of power and male dominance needs to be examined more closely – this would require bringing together the perspectives of social sciences into planning.

Planners need to look beyond the functioning of transport infrastructure and into the complex hierarchies that inform the daily mobility options for women, especially in the developing world. There is a need to contextualize spatial movements as they are rooted in a patriarchal culture that segregates people based on their gender (and other aspects of their identity). This inequality often seeps into urban planning and affects the type of activities one engages in and the legitimization of such access.

A gendered understanding of spatial planning highlights issues of safety and security and ensures that the quality of places and spaces reflects everyone’s needs.

After all, the potential for true development can only be unlocked when the public space has been reclaimed, every individual stands liberated and has the power to decide for themselves – whether to loiter or not.

Debarati Bhattacharya is a doctoral student at Centre for Environmental Planning and Technology (CEPT University), Ahmedabad.

Featured image credit: Reuters.

Why Elon Musk Isn’t Right About Nanotechnology Being ‘BS’

Nanotechnology isn’t science fiction – you can find it in the latest TV screens, solar cells and tennis rackets.

You might expect Elon Musk, the business magnate, engineer and serial entrepreneur would be a fan of all things techy. After all, his radical enterprises are built on pushing science to its limit. He’s behind a raft of visionary projects ranging from Tesla’s driverless electric cars and SpaceX’s self-landing reusable rockets to plans for 1,000kph “hyperloop” trains. But it appears there is a size limit to Musk’s technophilia. He recently tweeted that he thinks nanotechnology is “BS”.

Ahem, you have “nano” in your bio. That is 100% synonymous with bs.

— Elon Musk (@elonmusk) May 24, 2018

Folks on Twitter got a bit cross about this blanket dismissal of a field of research that bridges engineering, chemistry and physics. But Musk stuck to his guns, backing up his assertion by linking to Uncylcopedia, a crowd-edited satirical website, of all things.

Nano applies to everything & therefore means nothing. Definitely indicates bs. Sorry. https://t.co/WQp8j9YkeJ

— Elon Musk (@elonmusk) May 25, 2018

So is nanotech just a buzzword used to jazz up some otherwise dull research? Or is it a real branch of scientific discovery that’s actually making a difference to the world?

Nano means small, really small. One nanometre is just one billionth of a metre. At this scale we’re dealing with individual molecules and atoms (a carbon atom is about 0.3 nanometres across). So nanotech is about arranging matter that’s between one nanometre and 100 nanometres across in at least one dimension, to create usable medicines, electronics and materials.

The idea of deliberately doing science and engineering at this scale may well have started back in 1959, with a talk entitled ‘There’s Plenty of Room at the Bottom’ by the great physicist Richard Feynman. But, in fact, people in ancient times used nanotechnology to create stunning works of art, without realising the scales at which they were manipulating matter.

Quantum dots

Today we’ve purposefully harnessed nanotechnology to do some incredible things. Take quantum dots. They may sound like the name of a Belgian indie band but, in fact, these real and incredibly versatile nanomaterials are being used in medical imaging, display technologies and photovoltaic solar cells.

A quantum dot is a particle of semiconducting material, just a few nanometres in diameter. Due to their minuscule size, they have electronic properties that sit between what you would expect for a single molecule and a larger bulk material. One of the most useful outcomes of this is that the dots fluoresce (glow) with a colour that depends on the size of the particle. This means that by tweaking the size of the dot you can tune the colours they give off. And that property makes them an ideal candidate for use in your next flat screen TV.

Nanobiotechnology

Nature has a jump on us when it comes to nanotech. The protein molecules that replicate your DNA, digest your food and fight off infections are all nano-sized machines perfectly evolved to do a specific job in your bodies. This makes them ideal places to look for inspiration when trying to engineer something on the nanoscale.

A great example of this in action is a technique known as nanopore DNA sequencing. This technology involves proteins called porins that are normally used by bacteria to allow materials to enter and leave the cells. The porins are placed in a membrane to create channels or pores through it, and an electrical field is then applied. When DNA is forced through the pores the electrical current changes in response to the part of the DNA molecule (the base) that is in the pore.

By measuring the current as the molecule passes through the pore you can work out what the bases that comprise it are and sequence the DNA. This can be done at breakneck speed – up to 450 bases a second – using a tiny desktop device.

Graphene

You can’t mention nanotech without graphene cropping up. It’s been dubbed a wonder material due to its strength, conductivity and elasticity. Made up of two-dimensional arrays of carbon atoms arranged in a honeycomb pattern, graphene sheets can be just a few atoms thick but with a total area nearer the size of a poster.

When mixed with resins and plastics, the resulting material will be incredibly strong and lightweight. Graphene-based composite materials are already being used for a range of applications including sporting equipment and vehicle body panels. Meanwhile, graphene’s electrical properties mean it can also enhance battery technologies.

Doesn’t that sound like something an electric car manufacturer might want to look into?

Mark Lorch is professor of science communication and chemistry, University of Hull.

This article was originally published on The Conversation. Read the original article.

Five Chemistry Inventions That Enabled the Modern World

It turns out most people just don’t have a good idea of what it is chemists do, or how chemistry contributes to the modern world

Did you know that the discovery of a way to make ammonia was the single most important reason for the world’s population explosion from 1.6 billion in 1900 to 7 billion today? Or that polythene, the world’s most common plastic, was accidentally invented twice?

The chances are you didn’t, as chemistry tends to get overlooked compared to the other sciences. Not a single chemist made it into Science magazine’s Top 50 Science stars on Twitter. Chemistry news just don’t get the same coverage as the physics projects, even when the project was all about landing a chemistry lab on a comet.

So the Royal Society of Chemistry decided to look into what people really think of chemistry, chemists and chemicals. It turns out most people just don’t have a good idea of what it is chemists do, or how chemistry contributes to the modern world.

Chemistry hall of fame. Credit: Andy Brunning/[Compound Interest], Author provided

This is a real shame, because the world as we know it wouldn’t exist without chemistry. Here’s my top five chemistry inventions that make the world you live in.

1. Penicillin

Not a cowshed, but a wartime penicillin production plant. Credit: Wellcome Images

There’s a good chance that penicillin has saved your life. Without it, a prick from a thorn or sore throat can easily turn fatal. Alexander Fleming generally gets the credit for penicillin when, in 1928, he famously observed how a mould growing on his petri dishes suppressed the growth of nearby bacteria. But, despite his best efforts, he failed to extract any usable penicillin. Fleming gave up and the story of penicillin took a 10-year hiatus. Until in 1939 it took Australian pharmacologist Howard Florey and his team of chemists to figure out a way of purifying penicillin in usable quantities.

No, I rather not say cheese / Howard Florey. Credit: Wikimedia Commons

However, as World War II was raging at the time, scientific equipment was in short supply. The team therefore cobbled together a totally functional penicillin production plant from from bath tubs, milk churns and book shelves. Not surprisingly the media were extremely excited about this new wonder drug, but Florey and his colleagues were rather shy of publicity. Instead Fleming took the limelight.

Full-scale production of penicillin took off in 1944 when the chemical engineer Margaret Hutchinson Rousseau took Florey’s Heath Robinson-esque design and converted it into a full-scale production plant.

2. The Haber-Bosch process

Ammonia revolutionised agriculture. Credit: eutrophication&hypoxia/Flickr, CC BY-SA

Nitrogen plays a critical role in the biochemistry of every living thing. It is also the most common gas in our atmosphere. But nitrogen gas doesn’t like reacting with very much, which means that plants and animals can’t extract it from the air. Consequently a major limiting factor in agriculture has been the availability of nitrogen.

In 1910, German chemists Fritz Haber and Carl Bosch changed all this when they combined atmospheric nitrogen and hydrogen into ammonia. This in turn can be used as crop fertiliser, eventually filtering up the food chain to us.

Today about 80% of the nitrogen in our bodies comes from the Haber-Bosch process, making this single chemical reaction probably the most important factor in the population explosion of the past 100 years.

3. Polythene – the accidental invention

They may be plastic but they are vintage and very valuable. Credit: Davidd/Flickr, CC BY-SA

Most common plastic objects, from water pipes to food packaging and hardhats, are forms of polythene. The 80m tonnes of the stuff that is made each year is the result of two accidental discoveries.

The first occurred in 1898 when German chemist Hans von Pechmann, while investigating something quite different, noticed a waxy substance at the bottom of his tubes. Along with his colleagues he investigated and discovered that it was made up of very long molecular chains which they termed polymethylene. The method they used to make their plastic wasn’t particularly practical, so much like the penicillin story, no progress was made for some considerable time.

Then in 1933 an entirely different method for making the plastic was discovered by chemists at, the now defunct chemical company, ICI. They were working on high-pressure reactions and noticed the same waxy substance as von Pechmann. At first they failed to reproduce the effect until they noticed that in the original reaction oxygen had leaked into the system. Two years later ICI had turned this serendipitous discovery into a practical method for producing the common plastic that’s almost certainly within easy reach of you now.

4. The Pill and the Mexican yam

Yum - Mexican yam! Credit: Katja Schulz/Flickr, CC BY-SA

In the 1930s physicians understood the potential for hormone-based therapies to treat cancers, menstrual disorders and of course, for contraception. But research and treatments were held back by massively time-consuming and inefficient methods for synthesising hormones. Back then progesterone cost the equivalent (in today’s prices) of $1,000 per gram while now the same amount can be bought for just a few dollars. Russel Marker, a professor of organic chemistry at Pennsylvania State University, slashed the costs of producing progesterone by discovering a simple shortcut in the synthetic pathway. He went scavenging for plants with progesterone-like molecules and stumbled upon a Mexican yam. From this root vegetable he isolated a compound that took one simple step to convert into progesterone for the first contraceptive pill.

5. The screen you are reading on

LCD screens rock. Credit: Ian T. McFarland/Flickr, CC BY-SA

Incredibly, plans for a flat-screen colour displays date back to the late 1960s! When the British Ministry of Defence decided it wanted flat-screens to replace bulky and expensive cathode ray tubes in its military vehicles. It settled on an idea based on liquid crystals. It was already known that liquid crystal displays (LCDs) were possible, the problem was that they only really worked at high temperatures. So not much good unless you are sitting in an oven.

In 1970 the MoD commissioned George Gray at the University of Hull to work on a way to make LCDs function at more pleasant (and useful) temperatures. He did just that when he invented a molecule known as 5CB). By the late 1970s and early 1980s, 90% of the LCD devices in the world contained 5CB and you’ll still find it in the likes of cheap watches and calculator. Meanwhile derivates of 5CB make the phones, computers and TVs possible.

Mark Lorch tweets as @sci_ents

Mark Lorch is Senior Lecturer in Biological Chemistry at University of Hull.

This article was originally published on The Conversation. Read the original article.