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Is everything we learnt in GCSE chemistry a lie?

I've heard a lot of A Level students say this. Is there any truth to it? Can you all give examples?


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B_9710
18
There are a few simplifications, not lies as people try and say when they exaggerate. Like the 'shells' of electrons around the nucleus. The shells themselves are further divided.
At Key stage three you learn that an atom is the smallest building block of everything, gcse you learn of protons neutrons and the electron (subatomic particles), then you learn of quarks and all the even smaller entities at a-level and no doubt this continues through university. Lies is a rather sharp term, sometimes new content challenges what you learned previously.
Welp, with Chem at uni you find out a bunch of stuff you learnt at A-levels is wrong as an over simplification. It never stops.
What you learn at GCSE level is more simplified, so it's easier to remember. The information isn't necessarily wrong though.
Its just simplified not wrong.Like in physics you learn about newtonian physics.But the then you get to university and you learn about relativity.Newtonian physics is still ok for doing most things, still pretty accurate.Its just not the entire story,there is a deeper explanation.
Science consists of a set of models used to explain the world. People's ability to learn a certain model is limited to their technical understanding, so it stands to reason that simpler models are used at lower levels, does it not?
Its not a lie.
Original post by LordPhylogeny
Welp, with Chem at uni you find out a bunch of stuff you learnt at A-levels is wrong as an over simplification. It never stops.


This
Original post by pascalscasino
I've heard a lot of A Level students say this. Is there any truth to it? Can you all give examples?


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As others have said, there are (mostly) no lies, just simplification. At GCSE, you're told that molecules have intermolecular forces between them, well at AS, you're told about specific types of intermolecular forces and what causes them.

At GCSE, you're told about electrons being in shells around the nucleus, well at AS there are sub-shells in quantum shells that contain orbitals in them which house electrons.

At GCSE, you're told that something may be strictly covalent or ionic. Perhaps this may be considered a lie, since at AS, covalent bonds may be polar due to electronegativity difference, hence giving ionic character.

At GCSE, you're told that an ionic compound is formed when one atom gives electrons to another atom and they then attract each other electrostaticly as they're now oppositely charged ions. At A Level in general, you are told about what affects the feasibility (eg shielding, distance, size of atom )and how to actually prove the feasibility itself using half cells containing the reactants.

Think of A Level as filling in the lines of topics at GCSE, as well as adding some of its own.
in GCSE we got told that graphite conducted electricity because it had spaces between the sheets that allowed electrons to move through. but in A-level we learn that its because each carbon is only bonded to 3 other carbons and its unpaired electron delocalises creating a sea of delocalised electrons.
Reply 10
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B_9710
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Original post by marcobruni98
in GCSE we got told that graphite conducted electricity because it had spaces between the sheets that allowed electrons to move through. but in A-level we learn that its because each carbon is only bonded to 3 other carbons and its unpaired electron delocalises creating a sea of delocalised electrons.


Who the hell taught you at GCSE. I've never heard that ever. Man your teachers wanted you to fail.
Original post by B_9710
Who the hell taught you at GCSE. I've never heard that ever. Man your teachers wanted you tuo fail.


My school is not great... Nor does it have good teachers... But I guess it was an easy GCSE was of explaining why diamond does not conduct electricity but graphite does.
Original post by GradeA*UnderA
As others have said, there are (mostly) no lies, just simplification. At GCSE, you're told that molecules have intermolecular forces between them, well at AS, you're told about specific types of intermolecular forces and what causes them.

At GCSE, you're told about electrons being in shells around the nucleus, well at AS there are sub-shells in quantum shells that contain orbitals in them which house electrons.

At GCSE, you're told that something may be strictly covalent or ionic. Perhaps this may be considered a lie, since at AS, covalent bonds may be polar due to electronegativity difference, hence giving ionic character.

At GCSE, you're told that an ionic compound is formed when one atom gives electrons to another atom and they then attract each other electrostaticly as they're now oppositely charged ions. At A Level in general, you are told about what affects the feasibility (eg shielding, distance, size of atom )and how to actually prove the feasibility itself using half cells containing the reactants.

Think of A Level as filling in the lines of topics at GCSE, as well as adding some of its own.


Strictly not true, it isn't a result of the electronegativity difference, it is a result of the energy difference between the atomic orbitals as well as their integral orbital overlap being slightly lower. That is the reason, electronegativity difference also decreases with the same trend, it's a subtlety which doesn't get taught at A-Level. However, it is a property which trends well with it, so it is easier to explain it in terms of electronegativity.

You can't prove if a compound will be mostly ionic or covalent using half cells. Whether or not something is classed as ionic or covalent is again a matter of the level of integral orbital overlap and the atomic orbital energy difference. I think you're getting confused with redox and whether a certain compound will be reduced/oxidised or not depending on the overall cell potential (which is just a constant multiple of the gibbs free energy).
Reply 13
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B_9710
18
Original post by marcobruni98
My school is not great... Nor does it have good teachers... But I guess it was an easy GCSE was of explaining why diamond does not conduct electricity but graphite does.


Space between the sheets, that's crazy stuff. How is that even easier to explain.
Original post by B_9710
Space between the sheets, that's crazy stuff. How is that even easier to explain.

Like between the molecules... Idk tbh my teacher could not tell the difference between right and left... Needless to say I did not understand how conditions affect the position of equilibrium until year 12. Our teacher didn't even ever explain what the mole was....
Original post by Protoxylic
Strictly not true, it isn't a result of the electronegativity difference, it is a result of the energy difference between the atomic orbitals as well as their integral orbital overlap being slightly lower. That is the reason, electronegativity difference also decreases with the same trend, it's a subtlety which doesn't get taught at A-Level. However, it is a property which trends well with it, so it is easier to explain it in terms of electronegativity.

You can't prove if a compound will be mostly ionic or covalent using half cells. Whether or not something is classed as ionic or covalent is again a matter of the level of integral orbital overlap and the atomic orbital energy difference. I think you're getting confused with redox and whether a certain compound will be reduced/oxidised or not depending on the overall cell potential (which is just a constant multiple of the gibbs free energy).


First paragraph - fair enough Second paragraph - I wasn't stating that you could check if a compound is ionic or covalent using cells, just that you could check if the formation of an ionic compound is practical in nature and what affects it's practicality.

Also, you don't sound like an A Level student :smile:

Edit: Damn, gold in the chemistry challenge? I was happy with silver.
(edited 7 years ago)
Original post by GradeA*UnderA
First paragraph - fair enough


Hahaha
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oni176
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Original post by pascalscasino
I've heard a lot of A Level students say this. Is there any truth to it? Can you all give examples?


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No, it is not a lie. In fact, there are important knowledge that needs to be well known at GCSE level in order to prepare yourself for the A2.

A-level is an extension to the knowledge being taught at GCSE. For example, you have learnt the rate of reaction and collision theory at GCSE. At A-level you learn about Boltzmann distribution which links with the theory mentioned above. In addition, for organic chemistry, you probably know the general formula of alkanes and they can undergo complete and incomplete combustion. However, in Year 12 you learn about the free-radical substitution mechanism for example and some specific key terminology such as homologus series, homolytical fission, heterolytical fission etc. Same applies for alkenes where you learn about the mechanism of electrophilic addition.
Also, you face with new ideas, such as equilibrium and equilibrium constant.

AS level is an extension of GCSE knowledge and A2 is an extension of AS level knowledge.

I do however understand why someone has told you this opinion. The amount of knowledge that you learn at GCSE is restricted and covers the foundations of chemistry. A-levels are more demanding in comparison because there is more content with lots of explanations to different theories.
(edited 7 years ago)

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