Answer:
Only columns
Step-by-step explanation:
The properties of elements vary as you go across a period or down a column.
However, the properties are most similar as you go down a column.
That's because all the elements in a column have the same number of valence electrons.
For example, they may all want to gain one electron, so they will all form the same types of compounds.
The valence electrons determine the chemical properties, so the elements in the same column have the most similar properties.
