Periodycal #3

Rocket fuels, festive chemistry & chemistry arrows

Dec 13, 2022

Hello and welcome to the final Periodycal edition of the year! In this issue there are new graphics on rocket fuels and arrows in chemistry, some festive chemistry highlights from the web and social media, and the usual selection of interesting chemistry news and features.

Fueling rockets into space

Infographic on what fuels spacecraft. Solid propellants use granules of solid oxidizer mixed with powdered fuel, and liquid propellants use liquefied gases as oxidizer and fuel. Once spacecraft are in space, they can generate thrust from chemical reactions that produce gas (such as from the decomposition of hydrazine) or from accelerated ionized propellants. Other methods of propulsion are in varying stages of development. — Click to view and download the full graphic on the C&EN site

With NASA’s Orion capsule splashing back down to Earth safely over the past weekend, here’s a topical look at what got it up into space in the first place, in the latest edition of Periodic Graphics in C&EN.

If you want more detail specific to Artemis, there’s an excellent summary of the fuels used in the different engines on this NASA page – from the standard liquid oxygen and liquid hydrogen combination to the more varied range of liquid and solid fuels used in the boosters and in-orbit engines.

Festive chemistry

poinsettia plant snowflakes on red paper — Image © Angela Swartz

As the holidays approach here, I’ve been seeing some great chemistry-themed ideas, such as these poinsettia indicator paper decorations. There’s also this colour-changing corn syrup Christmas tree, with the aid of polarised filters:

Andres Tretiakov @Andrestrujado

Not a traditional chemistree but colourful & cheerful nonetheless. Corn syrup is a mixture of chiral sugars & is optically active. The 🌈 colours due to white light going through conc. sugar sol. between rotating linear polarisers. #OChemistree @RoySocChem

Andres also has a fluorescent version of the same tree which is equally fantastic.

Seen any other good festive chemistry decorations or ideas? Let me know!

A short guide to arrows in chemistry

Infographic highlighting different types of arrows used in chemistry. The graphic is broken into two sections: chemical reaction arrows and electron movement arrows. Chemical reaction arrows shown are the reaction arrow, the multiple steps arrow, the broken arrow, the reversible reaction arrow, the equilibrium arrow and the retrosynthesis arrow. Electron movement arrows shown are the resonance arrows and curly arrows. — Click to view and download this graphic on the Ci site

The latest graphic on the site is this one on the different arrows used in chemistry. I’ve been meaning to make this one since early summer, so it’s nice to have finally finished it off several months later!

I realised I haven’t been making as many of these basic chemistry primers of late, compared to back in the earlier days of the site. Is it something you’d like to see more of, alongside the usual content? Let me know in the comments.

A guide to snowflake shapes

Click to view and download this graphic on the Ci site

Here in the UK we’ve been getting snow in some areas, which is always a good opportunity to give this graphic from the archives an airing!

You can be the fun person at Christmas parties by pointing out that, yes, no snowflake is the same at a molecular level, but they can be grouped into 8 general categories, 39 intermediate categories, and a whopping 121 elementary categories.

For more snow and ice science, there’s also this previous edition of Periodic Graphics.

Chemistry news & features

Here’s the regular round-up of news and features I’ve found interesting over the past fortnight:

The UK is currently battling a shortage of antibiotics to treat strep A — This is a shortage I’ve had first-hand experience of, as we’ve had strep A brought home from the kids’ nursery, and I had to do an hour and a half tour of local pharmacies yesterday to find the last remaining supplies of phenoxymethylpenicillin – not even enough to make up the prescription we’d been given.
The brain chemicals that control what we enjoy — An interesting look at orexins, brain chemicals which have fundamental influences on our appetites.
C&EN’s molecules of the year for 2022 — Featuring the most magnetic molecule ever made, the electron-trapping perfluorocubane, and more.

That’s the end of another edition! All that remains is to wish you all an enjoyable break if you’re taking time out for the holidays in the coming weeks. Periodycal will be taking a brief break, too, so will return to your inboxes on 3 January next year.

Thanks for reading,

Andy