h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Entry: Metals and their Reactivity - a Beginners' Guide - A3805689
Author: Master B - Me and the farmer get on fine - U190397

About time I got round to writing something like this, really.

I think a lot of the Chemistry on hootoo is fairly dry and advanced, so I intended this to be accessible as possible.

To that extent, it does contain some degree of what Ian Stewart and Hoo tend to call 'lies-to-children', which I think are more than acceptable in the Guide.

Suggestions for additions are welcome, but the entry is quite long, so I am looking for trivia rather than particle physics please.

Very nice Entry, MB.

My initial comments:

Dunno whether it's worth putting in the mnemonics for the Reactivity Series:

(Please Stop Calling My Zebra In Class (KS3, KS4)[7 metals]

and (saying as a long word)
PoSoCaMaAlZiIrTiLeHyCoMeSiGoPt [14 metals]


Could also equate the metals' year/era of discovery with its reactivity (and hence method of extraction (Also, aluminium required the
development of electricity before it could be used in quantity).

Both excellent suggestions.

I tend to set mnemonics for my pupils as a homework exercise after I introduce them to the Reactivity Series, so I might cobble something together with the best of those - I've heard a dozen of them.

The discovery thing, I will add as a new subheader near the end, because it leads on well from the extraction thing.

B

P.S. The statue of Eros in London's Piccadilly is made from aluminium, as this was (at the time) a very prestigious metal.

Also, worth pointing out that the most familiar metals (everyday metals) which are hard and tough) are the 'transition metals'.

Check.

B

It's good, B.

(There's a 'ductility' in the bit on that property that should just be 'ductile')

Maybe elasticity should get a mention as a property? (How about an Entry on the engineering stress-strain curve, without actually having a picture?)

Even better, how about an Entry on the Iron-Carbon Phase Diagram, without a picture?!

Pin (wondering why he bothered with the other metals)

At the risk of getting off-topic, I started an entry on the martensitic transformation, but the first bit - on crystallography - got swallowed up by one of Hell's entries.

To try and keep space down, I could probably get away (restraining completely my engineering instincts ) with adding elasticity to the part on ductility and malleability.

B

Must be good for idiots - I understood it.

In the bit on aliminium oxide you mention scratching it to get a shiney bit, then go on to say this will appear - I think you mean disappear - or you mean seem to.

This has got to be the least boring science article written since Isaac Asimov passed away!

(Yes, that was a compliment)

Good job!

Hi Master B - this is an excellent entry. Well written, accessible, some humour - "ah yes, now you're talking"

I'm wondering if the heading is a bit off-putting? Before I read the article I was expecting something drier. Maybe it's the word "Reactivity"?

I didn't realise that electrons could form an impenetrable shield. Interesting, considering their relative mass.

"The voltage of a circuit is the amount of electrical energy available to it" - is this strictly true? I thought it had to do with the potential difference. This paragraph is one of the more complicated in your entry, and you might lose some people here.

"Metals higher than magnesium would quickly react with even weak acids, so would not be suitable." - first use of the word "acid". It appears to assume that everybody knows what you mean.

You mention that hydrogen and carbon are part of the Reactivity Series, but they are not themselves in the list. I can understand why, as they are not metals, but you assume in phrases such as "Hence, it is easy to tell which metals will react with acids and which won't". This is a very small point.

Despite having done chemistry a long time ago, I learned something, and that, is what this the guide is all about!

Very well done!

Woodpigeon

Great entry!

Just one thing I noticed in the "Displacement" section:

sulphur (sulphates and sulphates) > sulphur (sulphides and sulphates)

Oh, and footnote 4

All mistakes corrected - or at least those that have been pointed out.

Lady Brianna - Thanks. I take that as very high praise instead.

Woodpigeon - I can't really think of anything to change the title to, although I accept it is a bit stuffy. Open to suggestions on this one.

The 'impenetrable shield' bit is a lie-to-children (or lie-to-non-scientists, not to get patronsising). The actual truth is complicated and involves emission spectra and energy levels.

"I thought it had to do with the potential difference". Another lie-to-children. For the purposes of teaching electrical energy, potential (which is a type of energy, of course) = voltage.

I've tried to clarify the two paragraphs you mention.

Andy G - Yes, I thought you'd like that one...

B

Updated, with the suggestions from Post 2.

B

I use these dates for the use of metals:

Copper, gold (Near East) 8000 years BC (End of Mesolithic)

Tin and copper (smelting in Iran) 4000 years BC (Bronze Age)

Iron 2000 yrs BC (Iron Age)

This fits in nicely with the reactivity series)

What's your source, Al? (Archaeometallurgy is a personal interest)

Most sources (including Tylecote) say first artefacts in gold ~5000 BC

Copper smelting's probably right (Yahya?) but the tin is residual. The first true tin-bronzes are later (~3000 BC) and Sumerian.

Iron smelting from ores is right too at ~2000 BC, but there are examples of daggers and axes from meteoric and telluric iron that are a thousand years older.

Well, I can't really remember to be honest. I collect info from various sources and add it to a time line which I keep maintained.

However, one of the sources is

http://neon.mems.cmu.edu/cramb/Processing/history.html

Looking at this afresh, I can't see how tin was discovered as late as 1750 BC, when the Bronze Age started in some areas about 4000 years BC!
(Ah! Just re-read the text and it said that tin smelting commenced about 1800 BC)
Another is a publication of the International Copper Assaociation which says that, "A copper pendant found in what is now northern Iraq was made about 10000 years ago, when Europe was just emerging from the last great Ice Age.

I find it very hard to believe that civilized society dates back beyond 6-7000BC.

Updated - as an analytical metallurgist with not much archaelogical experience whatsoever, I'm taking your word for it on the dates.

B

"I find it very hard to believe that civilized society dates back beyond 6-7000BC".

Well, on my timeline (which, incidentally, I call 'The Technological Ages of Man') I have:

1. World's 1st large city? Gulf of Cambay, Indian State of Gujarat.
Discovered 01/02. Dates from 7000-8000 BC (i.e. In what I call 'The Copper Age').

2. Oldest house ever constructed in Britain dates back to 10000 BC (Mesolithic)

Fair do's. Be thankful I'm not a creationist, then.

B

Oops! That should have read 'Oldest stone house in Britain, Northumberland, dates back to 10000 BC