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Guru
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Metals, Semi-Metals and Earth Alkaline Metals

03/11/2007 8:41 AM

The transition elements, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn etc. are metals, while Al, Si, Ga, As, Se, Sn, Sb, Te and Pb are semi metals. The elements Li, Be, Na, Mg, k, Ca etc. are alkali and earth alkaline metals. This is what I learned as an engineer and mineralogist. But in recent books I see that Aluminium, Beryllium, Arsenic etc, refered to as metals, but by definition a pure metal is one that can be hammered or drawn to shape, ie, mallable and ductile. So why is it that I read in present day books about mineralogy the term metal is refered to any of these, including the alkali, earth alkaline, transition and semi-metals. They all have different chemical, physical and metallic properties?

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#1

Re: Metals, Semi-Metals and Earth Alkaline Metals

03/11/2007 11:34 PM

You are confusing the engineering definition of metal with the chemical definition. I didn't see youo list U, Rh, Zr, Ru, Bi, W. Your :drfinition: needs a reference. I can find you several dozen beside your rather mallable one.

RichH

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Guru
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#3
In reply to #1

Re: Metals, Semi-Metals and Earth Alkaline Metals

03/12/2007 7:51 AM

Hi NoSciFi. I know the peiodic table very well thankyou. I have every one of the different elements in my collection, also as a mineralogist and engineer I have worked with many of them. If I am writing an artical on mineralogy I state whether a chemical element is a metal, semi-metal, gas or otherwise. Also by the same token if I am writing an artical on engineering I state what the revalent element is, phosphourus for example can be alloyed with many metals, but phosphourus is not a metal and neither is silicon, but it too is alloyed with certain metals.

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#11
In reply to #3

Re: Metals, Semi-Metals and Earth Alkaline Metals

03/18/2007 9:57 PM

Well, I must say, I'm impressed! (That you have every one of the different elements in your collection). You could likely reap a tidy sum for some Francium! The last I knew, no visable amount of that element had ever been prepared. As late as 1995-2000, little was known about it's properties, it's so rare. Only a trace of Radon is available, as it is constantly decaying. Polonium is quite rare also, but it is used industrially, and reportedly, the Russians have found a new use for trace amounts of Polonium. Be careful of some of these "rare" and radioactive elements! I assume you weren't speaking of synthetic elements, like Plutonium and Californium, for example?

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Guru
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#12
In reply to #11

Re: Metals, Semi-Metals and Earth Alkaline Metals

03/19/2007 6:01 AM

Hi Cardio-2. Of course the elements, Francium and Radon are not included. What I am talking about here is all the elements that are normally available, but saying that, I have most of the elements in mineral compounds as well as the pure element. I do not have the transuranium elements and I do not want them. It is possible to buy a complete set of the elements on the internet, they are housed in a neat wooden case and produced in the USA. The way I got mine was to approach the different companies that refine them and beg or purchase them, more often than not they sent me a sample, it is amazing what one can get by just asking. I have worked with radio-active materials, "Iridium 196", this is highly radio-active so I do know the dangers and take the right precausions.

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Guru
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#2

Re: Metals, Semi-Metals and Earth Alkaline Metals

03/12/2007 6:56 AM

Aluminium is an interesting one. The reaction between finely divided aluminium and caustic soda produces sodium aluminate, with the emission of a large quantity of heat and with the aluminate behaving as a base.

Mercury is a metal that will not respond well to hammering at room temperature. It can be made into a very effective hammer if one casts it into a mould with a handle, and reduces the temperature until it freezes.

Iodine has metallic tendencies, yet it is in group 7 along with fluorine and chlorine, both gases.

Under certain conditions of temperature and pressure, hydrogen behaves like a metal.

Isn't the Periodic Table wonderful? http://www.webelements.com/

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#4
In reply to #2

Re: Metals, Semi-Metals and Earth Alkaline Metals

03/12/2007 8:18 AM

Hi PWSlack. Yes, I know that certain non metalic elements under certain conditions have metallic tendences, but these conditions do not occur on Earth under normal circumstanses such as high pressures or extreme low temperature. So when we are discussing native elements we have to do so under these normal conditions. I have worked with most of the elements either as an engineer or as a mineralogist, I also have a complete set of all the elements, and nobody in their right mind would call Beryllium a metal, it is an earth-alkaline metal. All transition elements (metals proper) are very stable under the prevailling conditions that exist on earth, while alkali and earth alkaline metals are highly reactive in our atmosphere. The halogens are also very reactive unless combined with an alkali or earth alkaline metal, flourite for examle, Ca F2.

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#5
In reply to #4

Re: Metals, Semi-Metals and Earth Alkaline Metals

03/12/2007 8:23 AM

Quite.

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#6
In reply to #4

Re: Metals, Semi-Metals and Earth Alkaline Metals

03/12/2007 10:37 AM

I agree, but didnt the original groupng of elements into these categories have more to do with the atomic number (or earlier the atomic weight, by Mendeleev) and the general repetition of similar properties than whether they were strictly metals, etc. by what one might call an "engineering definition"?

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#7
In reply to #6

Re: Metals, Semi-Metals and Earth Alkaline Metals

03/12/2007 11:26 AM

The joy of the Periodic Table is that it groups elements into order based upon their chemical behaviour so as to make some sense of it and to look for chemical similiarities.

Minerologists/geologists and other scientists, and chemical, civil, mechanical, control, electrical, software, marine and other engineers all speak different dialects and accents, both in terms of their location and culture, and in terms of their technical specialism. Their individual messages need to be interpreted by colleagues in other specialisms, making due allowance for the accent and dialect of a specialism that isn't one's own. Hence it is necessary to learn elements of these other 'languages' for the meaning to come through.

The term "engineering definition" is of principal focus, as the term will indicate different things to different specialists. For example, temperatures and pressures are of primary interest to the chemical engineer, who may have need to conceive a hammer made from Hg for a specific application even though, at ambient temperatures and pressures, the mechanical engineer may not have designed or constructed one before. While metals conduct electricity, the electrical engineer may have some input as to the choice of metal for a particular application: Na being a more hazardous choice than, say, Cu as the basis for an electrical conductor for a particular application. Grouping elements into other orders, as might be useful to the corrosion engineer is another way; Cu is near the bottom of the corrosion table. Another way of grouping may be needed for the for the electrical engineer, who places Cu near the top and Si near the bottom in terms of conductance. A minerals specialist may place Si near the top of a group, being an abundant material, and At near the bottom; indeed there are some elements in the Periodic Table that will be missing from this particular list as an indication of their absence from all available minerals. Another way of grouping is for the marine engineer, who may place Fe and its alloys near the top, whereas the aeronautical engineer looks at Fe in despair, placing Al and Ti near the top, etc., etc.

So the Periodic Table in itself may not necessarily be the best indicator of metallic properties for particular engineering applications as other indicators may be more appropriate.

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#8
In reply to #7

Re: Metals, Semi-Metals and Earth Alkaline Metals

03/12/2007 1:12 PM

Hi PWSlack. I wholeheartedly agree with you, myself I am a mineralogist but before that I was a marine engineer for many years. I speak five different languages and I understand their interpretations of the periodic table. In every country that do's not speak English they have different names for most of the elements, Kalium=potassium, Niobium=columbium, Tungsten=wolfram, Glucinium=beryllium, Jod=iodine, Silicium=silicon, Klor=clorine, Astat=astatine, Jern=iron etc, all these are the Scandinavian names of elements and some are the same in Dutch. Even so, their interpretation of the elements are the same as ours, and I have books in German, Norwegian, Swedish and Dutch explaing the properties of the elements and their uses, and in none of them does it say that Sodium is a metal, they say it is a alkali-metal.

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#9
In reply to #8

Re: Metals, Semi-Metals and Earth Alkaline Metals

03/12/2007 1:17 PM

The concept is that it is the dialect of the engineering language that determines the classification table used. The dialect of the national language is probably of a lower concern, n'est-ce pas? Danke fuer uns helfen.

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#10

Re: Metals, Semi-Metals and Earth Alkaline Metals

03/12/2007 3:41 PM

If cooled enough Hydrogen solidifies into a "metal" although one would be hard pressed to find if it were mallable. The definitions change as we learn more. There was a time when much of what you described as transition metals, alkali and semi metals were simply called "earth".

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