Teaching the Halogens: Some Ideas

How do you teach about the halogens? I am in the middle of teaching about them and thought it was worth telling you how I introduce the topic. I do like this topic as it provides lots of opportunities to link together parts of the course. Firstly, I will start with some theory, things such as the fact that the halogens are diatomic and are the only group whose members exist as solids, liquids and gases at room temperature. This then leads into ...

The Halogens and the Sea

There are a few references to lab work in this post – I do need to stress that any labs you carry out need to be under the supervision of one of your teachers (and risk assessed by the teacher) and carried out in school. I have always been fascinated by the link with the number of substances dissolved in the sea. For example, gold ions are dissolved in the sea and it is estimated that there are getting on for ...

Mercury rising?

If anyone eats swordfish they will know how tasty it is. Its steaks are similar to tuna steaks but maybe a little more 'meaty'. Unfortunately, swordfish has a tendency to accumulate high levels of mercury as methyl mercury. As in humans, the fish has no way of excreting the metal once it is absorbed. Image kindly reproduced according to the licence at: http://en.wikipedia.org/wiki/File:Xiphias_gladius1.jpg The mercury gets into the water through a variety of sources, from coal burning power stations to chlorine producing plants. Unfortunately, ...

Electrolysis saves the day

The Cutty Sark is a 19th Century Clipper ship. Built in 1869 to transport tea, the ship was built at a time when iron hulled ships were beginning to replace wooden ships. The Cutty Sark has a wooden hull fixed to a metal frame. For the past 50 years of so, the Cutty Sark has been kept alongside the River Thames in London in dry dock. However, every time it rains, the integrity of the ship was threatened (and believe me, ...