Periodic properties of group 1 and group 7 elements

Reaction of alkali metals with water:

http://www.youtube.com/watch?v=uixxJtJPVXk&feature=related

Reaction of sodium with chlorine:

http://www.youtube.com/watch?v=Ftw7a5ccubs

Reaction of some metals with oxygen:

http://www.youtube.com/watch?v=hQyJIxiSvUA&NR=1

Reactivity of halogens:

http://www.youtube.com/watch?v=u2ogMUDBaf4

Precipitation reactions:

http://www.youtube.com/watch?v=8RmVwz2fNGc&feature=related