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AQA AS Chemistry, unit 1

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What was the Q like?

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It was just something like, "What did JJ Thompson find out? What experiment did Rutherford and his team conduct to find that the positive charge was all in the central nucleus?" Not really exam-styled xD

Reply 121

Paulineuh

Original post by Cheryladair

Hey does anyone know any good sites for revising organic chemistry.
fractional distillation and cracking and all that kind of stuff?

My Chemistry teacher who teaches the organic side of the course raves about Chemguide, I don't really like it (maybe just the yellow page-ness lol) I prefer using my Nelson Thornes book :biggrin:

But here it is anyway:
http://www.chemguide.co.uk/orgmenu.html#top

Reply 122

gooner1886

I know this might be a simple point but does anyone get confused about when you are supposed to say "VDW Between MOLECULES" or when its supposed to be VDW between ATOMS

:redface:

Reply 123

maryamnc

Original post by Cheryladair

Hey does anyone know any good sites for revising organic chemistry.
fractional distillation and cracking and all that kind of stuff?

I dont know if it's any good for those but docbrown is a good website as is chemguide :biggrin:

Reply 124

maryamnc

Original post by gooner1886

I know this might be a simple point but does anyone get confused about when you are supposed to say "VDW Between MOLECULES" or when its supposed to be VDW between ATOMS

:redface:

Between molecules :smile:

Reply 125

gooner1886

http://a-levelchemistry.co.uk/

is an excellent website.

Reply 126

Paulineuh

Original post by gooner1886

I know this might be a simple point but does anyone get confused about when you are supposed to say "VDW Between MOLECULES" or when its supposed to be VDW between ATOMS

:redface:

I get confused between Alkanes and Alkenes sometimes so ... xD

Reply 127

Cheryladair

Original post by Paulineuh

My Chemistry teacher who teaches the organic side of the course raves about Chemguide, I don't really like it (maybe just the yellow page-ness lol) I prefer using my Nelson Thornes book :biggrin:

But here it is anyway:
http://www.chemguide.co.uk/orgmenu.html#top

Thanks! no mention of cracking though :frown:

Reply 128

gooner1886

Original post by maryamnc

Between molecules :smile:

Thanks.

Its always between molecules right? Never atoms?

Makes sense I suppose - since it is an interMOLECULAR force :redface:

(oops)

So e.g. when you're talking about why S has a higher melting point than P- you'd say it is a bigger atom, so has stronger VDW between molecules?

Reply 129

Cheryladair

Original post by gooner1886

http://a-levelchemistry.co.uk/

is an excellent website.

THANKYOU! They seem to have quite a bit :smile:

Reply 130

maryamnc

Original post by gooner1886

Thanks.

Its always between molecules right? Never atoms?

Makes sense I suppose - since it is an interMOLECULAR force :redface:

(oops)

So e.g. when you're talking about why S has a higher melting point than P- you'd say it is a bigger atom, so has stronger VDW between molecules?

Yup, it's a bigger atom and has more electrons so this means stronger VDW between molecules to more energy is required to overcome this

Reply 131

gooner1886

Original post by maryamnc

Yup, it's a bigger atom and has more electrons so this means stronger VDW between molecules to more energy is required to overcome this

Got it.

Thanks!!

Reply 132

gooner1886

What two definitions has everyone learnt for the definition of "relative atomic mass"?

Reply 133

Paulineuh

Original post by gooner1886

What two definitions has everyone learnt for the definition of "relative atomic mass"?

The weighed average of an atom of an element relative to 1/12th the relative atomic mass of C12.

Also, the equation:

Average mass of one atom of an element X 12/mass of an atom of 12C