I've trimmed this down to only include sites that still seem to work - unsurprisingly many of the ones from 2003 were dead links now!
Very useful resource for all the ACS-published chemistry journals. Everything back to the late 19th century (!) is apparently available online. You'll use this a lot in Part II year if you're at Oxford ...
This one has has been around for a while and was the go-to back when I was at Uni - for when you've just got to know the melting point of Niobium. Happens to me all the time, obviously ...
The Royal Society of Chemistry's online periodic table is, as you might expect, very rich in info, including links to other resources such as podcasts, videos and references galore.
Snazzy domain name ... this one is full of more practical usage and photos and such. Not so much with the detail, but more appropriate for general interest.
My weakest of the three disciplines - I therefore kept more links on this than anything else. These ones survived ...
Having trouble understanding Hund's Rules, or where they come from? This site describes them really well!
Dr Thomas' lecture notes and tutorials on Thermodynamics, Solutions and Molecular Interactions. This was handy for me as it was a topic I struggled with.
Great site describing most of the common and important terms and concepts in Atomic Spectroscopy. Easy to understand too.