Periodic Trends is a topic that is a foundation for your chemistry knowledge.
The following infographic has a monochromatic representation of the trends. Having the knowledge of these trends can help with your understanding of the behavior of the elements. Are there any that stand out? What pieces of information support your knowledge of the nature of some of these elements?
Why are some elements reactive and some are not?
Why are some elements reactive and some are not (specifically halogens)?