physical properties v chemical properties

[paul]

i've been reading about phenomena such as;

 

relative atomic mass

electronegativity

density

ionisation energies

melting point

atomic radius

electron affinity

boiling point

 

Q. which of these are PHYSICAL properties? and which are CHEMICAL properties?

 

Q. what is the difference between a physical property and a chemical property?

[DrP]

Chemical deals with the actual make up of the molecules and electronic structure. Physical deals with the 'physical' properties. e.g. when a liquid (like H20) boils there is a physical change from liquid to gas - but the chemical is still the same - it is still H20.

Same with melting point and density. The density of water changes with temperature (look at what hydrogen bonging does to water at/below 4C) - but it is still H20 - thus density is a physical property... What about the others?

[SFNfan#1]

relative atomic mass---------------Could be both but leaning on Chemical

electronegativity------------------Chemical

density------------------------Physical

ionisation energies------------------Chemical

melting point-----------------------Physical

atomic radius-----------------------Chemical

electron affinity------------------------Chemical

boiling point---------------------Physical

 

Chemical property relates to the Interaction of one element with another while physical property relates solely to that chemical. Often to observe a chemical property such as flammability, the chemical has to undergo a change. Let's say we're trying to find properties of Na or sodium. We have NaCl in a solution of water, they dissolve, so that can lead you to predict certain chemical properties. But to find the melting point of Sodium, all you have to do is burrn sodium in hot temperature. I tried my best to explain. Someone more expert on the field could clarify better!

[npts2020]

Maybe I am wrong but I always thought that all chemical properties were also physical properties but some physical properties are not chemical.

[ydoaPs]

Can we get this moved to Homework Help?

 

paul, what do you think the answers are?

[Klaynos]

I'm of the general oppinion that such decisions can't really be made.

 

Take the ionising energy, that is the energy that it takes for the least bound electron to be removed. That is clearly a physical effect (the loss of an electron), but it is a fundamental property in chemistry.

[npts2020]

I'm of the general oppinion that such decisions can't really be made.

 

Take the ionising energy, that is the energy that it takes for the least bound electron to be removed. That is clearly a physical effect (the loss of an electron), but it is a fundamental property in chemistry.

 

I know this is really splitting hairs but isn't the fact that an atom can lose an electron given certain impetus a physical property of the atom? (I agree that it is a fundamental chemical property as well)

[DrP]

Take the ionising energy, that is the energy that it takes for the least bound electron to be removed. That is clearly a physical effect (the loss of an electron), but it is a fundamental property in chemistry.

 

 

Anything that changes the molecule from one chemical to something different is chemical. If you lose an electron the atom/molecule becomes something different, the chemistry of that molecule or atom is different - thus the effect is chemical.

 

Some areas are taught in physics as well as chemistry (like density, ionisation,electricity etc..) and can be put into the area of chemical physics, but I would say ionisation energies are a chamical occurance.

 

 

Example of the fine line at a basic level:

Electricity! Chemical or physical or both? The properties of electrical circuits are covered as physics. The movement of the electrons is physics (or chemical physics - but is covered in chemistry lessons as well). The battery where these electrons are produced is covered as chemistry.

 

It is all physical science (Chemistry and Physics), our chemistry teacher told us that anything to do with electrons is chemistry. I've always thought of ionisation energies as chemistry- electrons are leaving atoms - thus the chemistry changes.

 

 

I would agree that it is a fine line though -- I was a bit confused by atomic radius - chemical or physical or both?.