Question

What are horizontal rows and vertical columns in a Mendeleev's periodic table known as?

Answer 1

Part 1: Mendeleev's Periodic Table

1. Mendeleev arranged the 63 elements known at that time in the increasing order of their atomic masses.
2. He suggested that the properties of elements are a periodic function of their atomic masses.

Part 2: Horizontal rows and vertical columns

1. The horizontal rows in Mendeleev's periodic table are known as periods.
2. The vertical columns in Mendeleev's periodic table are known as groups.