Tocatina
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Hi, can anyone explain to me what makes a substance polar/ non-polar? I know it has to do with the bonding, but I'm not quite sure how to explain it in an exam?
Polar vs Non-Polar (1 Viewer)
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jm1234567890
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some this is polar if it satisfys the following criteria:
1. it has O-H, O=H, etc.. so it can hydrogen bond
2. the atom is bent with free elections like water, this means it can perform dipole bonding
stuff that is generally non-polar are
hydrocarbons (alkanes, allkenes)
big molecules that bond using dispersion forces
this is hard to describe with out pictures
you should ask your teacher
1. it has O-H, O=H, etc.. so it can hydrogen bond
2. the atom is bent with free elections like water, this means it can perform dipole bonding
stuff that is generally non-polar are
hydrocarbons (alkanes, allkenes)
big molecules that bond using dispersion forces
this is hard to describe with out pictures
you should ask your teacher
Ragerunner
Your friendly HSC guide
most common to know is ethanol as being polar 
mon_mon
Member
non-polar look pretty symetrical, whereas polar can look weird.
crazylilmonkee
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polar substances eg water is said to have oxygen holding onto the electrons more readily. hence the 'bent' shape of a water molecule as the oxgygen is more negative than the hydrogens.. this enables water to be more dense than ice due to this structure and allows for hydrogen bonding...
i think thats it...
hmmmmmm check it tho
i think thats it...
hmmmmmm check it tho
iyamahobbit
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It's not really to do with symmetry. For example, water is polar, and it's also symmetrical.
Something is polar if it has a negative end, and a positive end. Anyway, read your textbook for more info, it's a bit hard to explain without diagrams and that.
~*HSC 4 life*~
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ok
in covalent substances, there can be 2 kinds of covalent bonds...
the first type is a pure covalent bond, which is a bond between elements with the SAME electronegativity (recall, electronegativity is the ability to attact electrons in a chemical bond). This means that pure covalent bonds only occur between the same element (as every element has a different electro neg) examples include Hydrogen gas (H2) Chlorine Cl2 etc
ahh hold up
my comp just went weird and its gonna shut down
ill write the rest later!
in covalent substances, there can be 2 kinds of covalent bonds...
the first type is a pure covalent bond, which is a bond between elements with the SAME electronegativity (recall, electronegativity is the ability to attact electrons in a chemical bond). This means that pure covalent bonds only occur between the same element (as every element has a different electro neg) examples include Hydrogen gas (H2) Chlorine Cl2 etc
ahh hold up
my comp just went weird and its gonna shut down
ill write the rest later!
~*HSC 4 life*~
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ok hi me again....hopefully my comp isnt gonna break down again!
the next type of covalent bond you can get is a polar covalent bond: this occurs between elements of different electronegativities, eg H2O, CO, HCl anything like that why? because there is an unequal charge distribution between the shared elements, due to the difference in electonegativities. Say we look at HCl: Chlorine is a a more electronegative element than Hydrogen, so when they bond together, the Chlorine atom can attract the hydrogen electrons toward itself so that it becomes slightly more negative (more neg electrons) and as a result Hydrogen becomes slightly positive. As you can see the distribution of charge is unequal as the chlorine is more negative and hydrogen positive, when they form slightly positive and negative charges, the molecule forms a dipole.
okay now; chemsitry never just stops there. We've discovered pure and polar covalent bonds...however theres another concept we need to know, that is non-polar and polar molecules.
A molecule is polar where there is a polar bond as explained above, an unequal charge distribution and dipole formed, and a non-polar molecule can be one with a pure covalent bond, since it does not have an unewual chage dist in its bond. Ok but it is chemistry so there are exceptions
you can get some substances with polar bonds that are actually nonpolar molecules, this is because when we consider the whole molecules net charge distribution they cancel out due to structure etc that people have explained above ie a symmetical molecule such as methane, its geometry is a tetrahedral molecule, so all the dipoles cancel eachother out..i can imagine at this point it sounds confusing, without diagrams or a teacher to talk you through it...so make sure you ask someone face to face hehehe
another example which you wll come across is carbon dioxide, igf you look at its lewis dot structure, you can see its of linear geometry, which is considred to be symmetrical, because the 'arrows' which are drawn from positive to neg (vectors)
cancel eachother out, one goes to the right, the other gors to the left therefore it ends up back where it started, zt zero so it is non polar
gtg!!!
dumb comp1
the next type of covalent bond you can get is a polar covalent bond: this occurs between elements of different electronegativities, eg H2O, CO, HCl anything like that why? because there is an unequal charge distribution between the shared elements, due to the difference in electonegativities. Say we look at HCl: Chlorine is a a more electronegative element than Hydrogen, so when they bond together, the Chlorine atom can attract the hydrogen electrons toward itself so that it becomes slightly more negative (more neg electrons) and as a result Hydrogen becomes slightly positive. As you can see the distribution of charge is unequal as the chlorine is more negative and hydrogen positive, when they form slightly positive and negative charges, the molecule forms a dipole.
okay now; chemsitry never just stops there. We've discovered pure and polar covalent bonds...however theres another concept we need to know, that is non-polar and polar molecules.
A molecule is polar where there is a polar bond as explained above, an unequal charge distribution and dipole formed, and a non-polar molecule can be one with a pure covalent bond, since it does not have an unewual chage dist in its bond. Ok but it is chemistry so there are exceptions
you can get some substances with polar bonds that are actually nonpolar molecules, this is because when we consider the whole molecules net charge distribution they cancel out due to structure etc that people have explained above ie a symmetical molecule such as methane, its geometry is a tetrahedral molecule, so all the dipoles cancel eachother out..i can imagine at this point it sounds confusing, without diagrams or a teacher to talk you through it...so make sure you ask someone face to face hehehe
another example which you wll come across is carbon dioxide, igf you look at its lewis dot structure, you can see its of linear geometry, which is considred to be symmetrical, because the 'arrows' which are drawn from positive to neg (vectors)
cancel eachother out, one goes to the right, the other gors to the left therefore it ends up back where it started, zt zero so it is non polar
gtg!!!
dumb comp1