Recent Posts by David Allen

William Ramsey

On Wednesday 2nd October you may have seen the Google doodle with Sir William Ramsey (it was published to celebrate his 167th birthday): Image credit / copyright Google.com – if there is a problem post this image, please let me know and I will remove it. You may also have inferred from the doodle that William Ramsey had something to do with the noble gases (group 18)… more on this later. William Ramsey was Scottish and was born in Glasgow on the 2nd ...

E/Z cis / trans – geometric isomers

The E/Z or cis / trans system can be used to name geometric isomers. Geometric isomers are molecules that have groups above and below the plane of a ring or double bond. It is important to consider and be aware of these isomers as even though the structural formula is the same, the molecules will have different physical properties and can have different chemical properties. So to make life easier, we have two systems for distinguishing between them. The cis trans ...

Primo Levi

The aim of this post is to give you some ideas for furthering your teaching of the international dimension. You may or may not heard of Primo Levi. I came across his name recently when carrying out some research into graphene. The name seemed unusual to me and I thought I would dig a little deeper and see what I could find out. Boy, was I happy that I did this – what a guy! Primo Levi was born in Italy (Turin) ...

Acid Base Theory

I’m just about to start teaching the acids and bases topic to my students. Acids and bases are interesting compounds because the terms ‘acid’ and ‘base’ are just labels we have given to explain different types of reactions. The topic always starts with an introduction to acid base theory and usually covers the ‘Bronsted Lowry’ theory, as well as the ‘Lewis’ theory (of acids and bases). So what are these different theories and are there any differences between what is a ...

Silver chemistry

Silver offers some interesting opportunities to do something different with your teaching. You may teach about it / include it when you are looking at the halogens or when covering redox reactions. I hope this blog post gives you some ideas. If you are including some silver chemistry in your teaching of redox you will probably cover disproportionation – a redox reaction where a species of the same element (it may be the same element in a compound) gets simultaneously oxidised ...

Hydrogen

By Wednesday, July 10, 2019 No tags 0

We are currently having a space themed week in school to celebrate the 50th anniversary of the moon landings. not quite the 50th anniversary, more like 49 and 49/50ths (Armstrong walked on the lunar surface on the 16th July 1969) but as we break up on Friday it was the best the school could do. The students have a few days off timetable and are engaged in many different activities that relate to the moon landings. In chemistry, I guess we have ...

Equilibria part 2

By Monday, July 8, 2019 No tags 0

Last month I ran over the basics of equilibria. The rationale for this was that I felt that it was a part of the course that had been poorly answered in the recent IB May examinations. I do need to stress that this is my own personal opinion and not that of the IB. This month I will run over the more difficult concepts associated with equilibrium, Le Chatelier’s principle. Le Chateliers principle allows you to determine what happens to a system ...

Forwards, backwards, left or right? – Equilibria Part 1

By Friday, July 5, 2019 No tags 0

There were a few questions on equilibria in this year’s May exams. As a teacher I felt that students didn’t perform very well on these questions (I have no evidence for this apart from conversations with a very small number of students who sat the exams) so thought that this month may be an opportunity to help reinforce and summarise some of the concepts covered. First of all, what do we mean by equilibrium? A reaction that is at equilibrium doesn’t ...

Chernobyl

By Monday, July 1, 2019 No tags 0

I’m half way through watching the new HBO / Sky miniseries Chernobyl. Have you seen it? Here in the UK it has received some great reviews with some critics claiming it is the best TV series ever produced. Chernobyl, as you probably know was a nuclear power station in the Ukraine that exploded with catastrophic consequences in 1986. If you study option C, Energy you will look at nuclear fission and fusion in section C3. Chernobyl was a fission reaction. In a ...

Using Catalysts in Lab Work – a Slightly Different Approach

By Friday, June 28, 2019 No tags 0

I imagine that, as teachers, we all carry out a hydrogen peroxide decomposition using manganese dioxide. We may also demo cracking where we use aluminium oxide or silicon oxide as a catalyst. This aside, do we really make much use of catalysts in our lab work? https://www.youtube.com/watch?v=p5qvi20J5IM The other day I was carrying out a lab with my students that involved collecting hydrogen by upwards displacement of water, using magnesium and hydrochloric acid. We are also fortunate to have a fantastic lab ...

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