What are two of the trends that are found in the periodic table?

On the original series, MacGyver was a television character that could build things from everyday objects, frequently using chemistry and his knowledge of the many trends in the periodic table. What are two of the trends that are found in the periodic table? What is responsible for each of these trends occurring within the periodic table? Use this information to explain what part of the periodic table would contain the best elements to use from the trend that you selected.