(Potentially) Useful sources for allotropes required by IB:
UK source on Period 3 oxides: http://www.chemguide.co.uk/inorganic/period3/oxidesphys.html
(It contradicts the text because it states that SiO2 won't conduct electricity as a liquid--molten state--or a solid...bottom of p. 120 in text says molten SiO2 has freely moving electrons...molten form/structure of giant, network covalent structures is not well-established.)

More on SiO2 and carbon allotrope properties:
http://www.docbrown.info/page04/4_72bond4.htm (Seems fairly reputable but not specific to IB...UK Advanced Level represented)
http://www.patana.ac.th/parents/curriculum/chemistry/units/LR404.html (Not sure how reputable...British International School in Bangkok?)

Richard Thornley's Allotrope video: https://www.youtube.com/watch?v=GIHmfBsHsCY

One of Ms. Clewett's favorites: http://www.msjchem.com/topic-4-bonding.html
Accompanying worksheet with answers:

Richard Thornley is an over-achiever! He has posted 37 videos for Topic 4, from <1 minute to about 5 minutes (with one at 13:40 showing Lewis structures): https://www.youtube.com/playlist?list=PL816Qsrt2Os2JeMAYHMGBEEbZG5K7XSTX

Bozeman Science basic primer on bonding: https://www.youtube.com/watch?v=7DjsD7Hcd9U

Crash Course bonding video: https://www.youtube.com/watch?v=QXT4OVM4vXI

Very simple video on bonding: https://www.youtube.com/watch?v=NgD9yHSJ29I

Very simple video on polarity: https://www.youtube.com/watch?v=LKAjTE7B2x0

Simple but "nice" video showing molecular geometries: https://www.youtube.com/watch?v=i3FCHVlSZc4

"A Level Notes" (a couple minor typos, but generally short and sweet): http://alevelnotes.com/Bonding/130

(From Nisbah website: https://sites.google.com/a/nisbah.com/chemistry/IBDP-Chemistry/dp-chemistry)
Chemical Bonding1[PPT] Download OR Chemical Bonding and VSEPR [PPT] Download OR
Naming Compounds [PPT] Download OR

Emma Osgood slides:
Emme Isom recommendations & notes:
Angel Paz recommendations & notes:
Allyssa Corpuz notes & recommendations:

Note that old syllabus name "Dative bond" has been replaced with current syllabus name "Coordinate covalent bond."

Data from CO2 monitoring at the Mauna Loa Observatory:
http://www.esrl.noaa.gov/gmd/ccgg/trends/monthly.html (monthly)
http://www.esrl.noaa.gov/gmd/ccgg/trends/full.html (full record)