Q1. Describe how Mendeleev organized his periodic table.

A1.  Mendeleev organized his periodic table in rows by increasing atomic mass.


Q2.  Explain why Mendeleev left a space for the unkown (at the time) element germanium in his periodic table.

A2.  His periodic table was sorted in increasing atomic mass, which was a pattern. He was unable to match some of the elements in the pattern, so he left it blank. He did however (successfully) predict the properties of germanium.


Q3. State the property used to organize elements in the modern periodic table.

A3. They have groups, which are columns, and also periods which are rows. The modern periodic table organizes elements by atomic number. When the elements are arranged in this way, elements that have similar properties appear at regular intervals.