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Heavy metals are generally defined as metals with relatively high densities, atomic weights, or atomic numbers. The criteria used, and whether metalloids are included, vary depending on the author and context. In metallurgy, for example, a heavy metal may be defined on the basis of density, whereas in physics the distinguishing criterion might be atomic number, while a chemist would likely be more concerned with chemical behaviour. More specific definitions have been published, but none of these have been widely accepted. The definitions surveyed in this article encompass up to 96 out of the 118 known chemical elements; only mercury, lead and bismuth meet all of them. Despite this lack of agreement, the term (plural or singular) is widely used in science. A density of more than 5 g/cm3 is sometimes quoted as a commonly used criterion and is used in the body of this article.
The earliest known metals—common metals such as iron, copper, and tin, and precious metals such as silver, gold, and platinum—are heavy metals. From 1809 onward, light metals, such as magnesium, aluminium, and titanium, were discovered, as well as less well-known heavy metals including gallium, thallium, and hafnium.
Some heavy metals are either essential nutrients (typically iron, cobalt, and zinc), or relatively harmless (such as ruthenium, silver, and indium), but can be toxic in larger amounts or certain forms. Other heavy metals, such as cadmium, mercury, and lead, are highly poisonous. Potential sources of heavy metal poisoning include mining, tailings, industrial waste, agricultural runoff, occupational exposure, paints and treated timber.
Physical and chemical characterisations of heavy metals need to be treated with caution, as the metals involved are not always consistently defined. As well as being relatively dense, heavy metals tend to be less reactive than lighter metals and have far fewer soluble sulfides and hydroxides. While it is relatively easy to distinguish a heavy metal such as tungsten from a lighter metal such as sodium, a few heavy metals, such as zinc, mercury, and lead, have some of the characteristics of lighter metals, and, lighter metals such as beryllium, scandium, and titanium, have some of the characteristics of heavier metals.
Heavy metals are relatively scarce in the Earth's crust but are present in many aspects of modern life. They are used in, for example, golf clubs, cars, antiseptics, self-cleaning ovens, plastics, solar panels, mobile phones, and particle accelerators.

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  1. greatestdancer

    Guttering / DW Waste Pipe Heavy Rain problem

    In my kitchen, I have a dishwasher waste pipe - it is routed into black pipe that runs from the roof (guttering) to the ground (outside). Normally this is fine, but if I get heavy rain, the pipe that both the guttering and DW waste pipe are routed into fills faster than it can drain away, and...
  2. M

    URGENT Heavy Rain water into flue and boiler

    Hi All, Had this problem earlier, just changed to combi boiler last year end .whenever it rains heavily, water comes heavily from the pipe and spoilt the boiler parts in boiler. As this was covered, gas engineer from vailliant eco 835 changed the parts and it looked fine for two weeks. Since 2...
  3. A

    Whole House Filters - Heavy Metal Removal

    Good evening all, hope everyone is keeping well. First of all I hope this thread is in the right place, it didn't really fit into any other sections. Please let me know if it belongs elsewhere, and i'll move it! I've had a look around the forum and not found an answer to my question, at least...
  4. P

    Irwin Tilmor TUL223 heavy duty pipe bender

    I'm trying to find a spindle pin for this bender. This is the 19mm pin which goes through the quadrant bit then the bender frame, the bending arm, and out the other side. Irwin UK have told me this is only available as part of the quadrant assembly (Part No.T220H in their catalog, or part H in...
  5. C

    Tips and tricks with heavy boilers

    Hi all, I’m currently building my portfolio which is going great. I have a fantastic mentor too. Today’s install was a boiler in the loft. If you’re working on your own, how do you manage getting boilers into the loft? I know a bit of muscle but... I was just wondering if there’ any lifting...
  6. D

    Heavy corrosion on new copper

    Hi. Could anyone shed some light on a reason for this excessive corrosion. The pipes are 3 months old, inside a wooden clad room, I can't see any sources of any leaks. The corrosion seems to be near the holes in the wall. Is this a chemical reaction from the wood treatment ? Many thanks.
  7. B

    Heavy rad Quinn special order

    These are beyond plasterboard fixings,plasterer had not put enough dab behind the board so could not go on today,even though we sprayed blue paint on the wall saying heavy dab here FFS,not fussed on the colours ,Red one was the heaviest rad i have ever lifted,3 of us and we still struggled
  8. Eyespy999

    SDS drill or core drill

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  9. Best

    How heavy is yours?

    Have been lugging my tool case about and finding it very tiring. Today was just too much as I was going up several flights of stairs to a flat with it. It is my "small tools" tool case, but has every spanner, grips, screwdrivers, pipeslices, large pipe cutters, snips, pliers, etc that I usually...
  10. rpm

    Aladdin isolator - bit heavy.

    Brought an Aladdin easy fit isolator for a job rather than drain down the house just to remove the toilet pan but it weighs 13oz / 360gms which seems a lot of weight to put on the copper cistern feed pipe and the only place it can go is right up close to the fill valve plastic stem connection so...
  11. Eyespy999

    Drain Cock Type A Heavy Pattern 15mm

    Hello all I was wondering if this type of drain cock can be fitted straight into a compression joint or whether it is best practice to solder into a fitting ie straight connector with a short piece of copper pipe fixed into the fitting. many thanks for any help.
  12. R

    Stanley Fatmax Plumbing Bag

    Hi, anyone got a Stanley Fatmax Plumbing bag? Pros/Cons please Cheers
  13. G

    Another analyser thread

    Alright lads and ladies. just in the process of getting an analyser for work and I'm thinking about ordering the testo 330-2 ll pro kit. In the future I'll be working on oil boilers but noticed it said light oil. Not worked on oil before so am I likely to come across heavy fuel oil or will...
  14. M

    Decent dust sheets.

    I am after a few decent dust sheets. The ones I have are rubbish dust still goes through them. What I am after is like what I used when I subbed for BG as they were great.
  15. plumb_know

    What fixings do you find best for plasterboard

    Hi, just wondering what fixings you lot use for plasterboard, recently used the screw type where you screw the fixing into the wall then a screw goes into this. Found them pretty pants, just tear the wall apart and pull out. What do all you lot use? thanks
  16. D

    heavy heart.

    Just arrived home after seeing a good friend take his last breath, I was to honoured to have been there at the end. This was a man when had dodged a snipers bullet in the Falklands, had survived many armed patrols over here in Northern Ireland. A man who had walked away from a high speed...
  17. M

    Is the Marcrist DDM2 or DDM3 to heavy?

    I have just tried a friends DDM2 core drill and I am concerned that it is too heavy for general core drilling for waste and flue holes. How do other users get on with the weight compared to other drills? I have only ever used a Makita 850W before which was fairy light.
  18. B

    how much does a potterton flamingo 50s weigh?

    omg, i nearly broke my back....never anticpated a boiler being that heavy....at least 60kg right? any other boilers that heavy out there?
  19. K

    Expansion tank heavy can I drain it?

    Hi guys, My expansion tank feels really heavy and is starting to come away from the wall. I live in a Barratt home and it has fell of on e already and put back on the wall. Can I drain it? If not it's fine I will get someone in but as it's not related to the boiler wondered if I could do it...
  20. gassafe

    Heavy designer rad on plasterboard...

    Customer wants there designer rad on plasterboard wall! It's heavy one, I have hung one before probs 50 - 60 kg but that was on a solid wall! I always understood the fisher type expander / umbrella fixing to be the strongest, when used with the setting tool! But was not too sure about putting...
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