Quick Chemical Formulas

ChemEqn app.

While teaching chemistry this year, I’ve needed a quick way to write chemical formulas. The fastest thing to do is just write it out flat–sans sub and superscripts–like Na+, or CO2-. But that’s not pretty, and introduces another potential element that could confuse.

I found that you can use Lingojam’s sub and superscript generators to copy and paste the official UTF-8 characters for pretty much all the sub and superscripts I need for chemistry, but that takes a while to do.

So instead, I put together, just in time to write my finals, a little ChemEqn app that uses keyboard shortcuts to quickly substitute in the sub and superscripts as you type.

[Ctrl][number]: give you the number subscripted:
- e.g. [Ctrl][2]: gives ₂
[Ctrl][Shift][number]: gives superscripts:
- e.g. Ctrl][Shift][2]: gives ²
[Ctrl][Shift][+]: gives a positive charge (⁺)
[Ctrl][Shift][-]: gives a negative charge (⁻)
[Ctrl][>]: gives a forward arrow (→)
[Ctrl][<]: gives a backward arrow (←)
[Ctrl][/]: gives the double arrow (⇌)

The method is not perfect, since you still have to decide which comes first when you have both a sub and superscript after an element (O₃²⁻ for example). Another issue is that when I do [Ctrl][Shift][+] and [Ctrl][Shift][-] it zooms into and out of the browser window since we’re using the default zoom shortcuts, but that’s, at least for me, a minor inconvenience.

I do like the app since it still makes for quite readable formulas that can be easily copied and pasted almost anywhere without messing up since it only uses UTF-8 characters that are pretty standard across the web (and most computer programs).

Electron Configuration Practice

A quick electron configuration practice webpage that lets you enter the symbol for an element and see if you can write out the electron configuration in both the full and noble gas forms.

Screen capture from the electron configuration webpage. Sulfur (S) is entered, and then the long form and noble gas form of the configurations can be entered and checked. In this case, there is an error in one part of the noble gas form.

The table at the bottom is a guide to filling the electron shells and orbitals. You can click any of the blue squares to change the number of electrons in the orbital.

Update

An improved version of the lower, table part is here.

The Wind Right Now

Windyty shows beautiful animations of the current wind patterns around the world.

Updated Atom Builder

A couple of my students asked for worksheets to practice drawing atoms and electron shells. I updated the Atom Builder app to make sure it works and to make the app embedable.

So now I can ask a student to draw ²³Na⁺ then show the what they should get:

Worksheet

Draw diagrams of the following atoms, showing the number of neutrons, protons, and electrons in shells. See the example above.

¹⁴C: answer.
³²K⁺: answer.
¹⁸O^2-: answer.
⁴He²⁺: answer.
³²P^–: answer.

I guess the next step is to adapt the app so you can hide the element symbol so student have to figure what element based on the diagram.

Embedding more Graphs (using Flot)

Here’s another attempt to create embeddable graphs of mathematical functions. This one allows users to enter the equation in text form, has the option to enter the domain of the function, and expects there to be multiple functions plotted at the same time. Instead of writing the plotting functions myself I used the FLOT plotting library.

Investigating the Heart Online

BodyXQ has one of the most impressive interactive apps of the heart that I’ve yet seen.

You can explore the heart in 3D while it’s in motion. You can see the valves open and close, while hearing the beat. I’m going to have to show this to the class tomorrow.

3d Molecule Viewer

An excellent 3d viewer for molecules.

In addition to the existing molecules, you can import any number of others if you can find them in one of the right formats (PDB, SDF or MOL molecule definitions): the ligand.info: Small Molecule Meta Database is a good source for SDFs.

An Online Microscope

Now that I have a new set of microscopes I didn’t think I would actually need to have an online, simulated microscope to show samples. However, I thought having a series of picture that I could scroll through would be useful to illustrate microscopy concepts such as depth-of-field when I talk about them to the whole class. Once I’d created the depth-of-field simulation, I figured it would not be too much extra trouble to put in a few different magnification levels. Now I have this embeddable online microscope simulator.

It’s started off with a single fly wing as a sample, but I’ll be adding to it as I take more pictures.