The answer to this question is theory
Answer:
<em><u>Rows in the periodic table are called periods</u></em>. As one moves from left to right in a given period, the chemical properties of the elements slowly change. <em><u>Columns in the periodic table are called groups</u></em>. Elements in a given group in the periodic table share many similar chemical and physical properties
Explanation:
You can find this on google easily
