monomers

[paul]

i've heard monomers described as,

 

"simple organic compounds which can link with other compounds to form polymers"

 

Q. are monomers always organic? and does organic always mean containing carbon?

 

Q. who simple does a molecule/compound have to be to be labelled 'simple'?

 

Q. how large/complex does one have to be to be called a macromolecule?

[insane_alien]

monomers don't need to be organic at all. although you'd be hard pressed to find many inorganic ones, silene(silicon analogue of ethene) would be one. and i'm pretty sure sulphur can form chains.

 

organic means containing carbon although not all things that contain carbon are organic.

 

simple is a bit of a vague term, if the molecule involves secondary structure then it definitely isn't simple. IIRC simple extends to a medium length chain with a few branches and/or functional groups attached.

 

macro molecules are typically proteins or large lattices such as diamond or graphite along with extremely long chain hydrocarbons like plastics.

 

rule of thumb would be if its molecular weight is a few thousand daltons then its probably macro.

[nitric]

for simple i would agree that it would be at max length 4-6 carbons and less than 4 substitutes on it, consisting mainly of carbon and hydrogen...

[paul]

thanks a lot guys.

 

alien, you mentioned diamond and graphite as being macromolecules; is DNA also a macromolecule?

 

also, you said momomers don't have to be organic, but usually are - then you said sulfur can form chains; do you mean compounds containing sulfur - or just sulfur (because i thought monomers were compounds linked together, as opposed to "single element molecules")?

 

one last question; i've now read many definitions of monomers; one says, "...linked to other identical molecules." ; so a monomer is a relatively small chain of IDENTICAL molecules? it can't be a number of different molecules linked together?

[DrP]

thanks a lot guys.

 

alien, you mentioned diamond and graphite as being macromolecules; is DNA also a macromolecule?

 

also, you said momomers don't have to be organic, but usually are - then you said sulfur can form chains; do you mean compounds containing sulfur - or just sulfur (because i thought monomers were compounds linked together, as opposed to "single element molecules")?

 

one last question; i've now read many definitions of monomers; one says, "...linked to other identical molecules." ; so a monomer is a relatively small chain of IDENTICAL molecules? it can't be a number of different molecules linked together?

 

 

It's from latin. Mono-Mer - 'Mono' meaning single, 'Mer' meaning unit.

Also - Poly-Mer - 'Poly' Meaning many, 'Mer' - again meaning unit or units.

 

Therefore - Monomer = single unit or building block. Polymer = many units - usually a long chain in chemistry.

 

 

 

DNA is a very large molecule and, I would presume, is classed as a macromolecule. (again - this is probably latin - 'Macro' meaning very large I think!?)

[UC]

thanks a lot guys.

 

alien, you mentioned diamond and graphite as being macromolecules; is DNA also a macromolecule?

 

also, you said momomers don't have to be organic, but usually are - then you said sulfur can form chains; do you mean compounds containing sulfur - or just sulfur (because i thought monomers were compounds linked together, as opposed to "single element molecules")?

 

one last question; i've now read many definitions of monomers; one says, "...linked to other identical molecules." ; so a monomer is a relatively small chain of IDENTICAL molecules? it can't be a number of different molecules linked together?

 

Of course a polymer doesn't have to be all identical molecules. But you need a confined set of possible units. Take DNA (The enzyme that assembles it is called DNA polymerase, so gives you a hint there). There are 4 different monomers. Granted, it is a very precisely assembled polymer, but a polymer none the less. Proteins would also be polymers. They have quite a few options of monomer units, but are all linked with peptide bonds. Generally the number of bond types making up the backbone of the chain (if it's a chain polymer) is small

 

As for inorganic polymers, polydimethylsiloxane walks the line between organic and inorganic. How about red phosphorus? It has a polymeric structure and yet is a pure element.

 

Generally when we think of polymers, we think of long chains, but this is not always the case. How about polycarbynes? These are random network polymers and precursors to synthetic diamond. Each monomer unit attaches to three others and you get a tangled mesh as a result.

[John Cuthber]

Some of the silicates can be considered as polymers and are inorganic.

Just in case anyone wondered, the term for a few polymer molecules stuck together is oligomer.

Nitric's idea of "simple" would rule out most nylons, a lot of polyurethanes, aand some other well known polymers like kevlar and polycarbonate. However, the definition of all the terms you ask about probably depends on circumstances and the people talking about them