[sagazi]

How do you predict properties of elements by extrapolation?
i.e. melting point, boiling point, atomic radius, first ionization energy, formula of the oxide?

Thanks =)

[Yggdrasil]

Here's a good starting point to look at:

http://en.wikipedia.org/wiki/Periodic_trends

Your chemistry textbook should also have a more in depth discussion of the topic.