Question

are horizontal rows numbered 1 to 7​

Answer 1

Explanation:

The elements are arranged in seven horizontal rows, in order of increasing atomic number from left to right and top to bottom. The rows are called periods, and they are numbered from 1 to7

Answer 2

Answer:

The elements are arranged in seven horizontal rows, in order of increasing atomic number from left to right and top to bottom. The rows are called periods, and they are numbered from 1 to 7.

Explanation:

There are eighteen vertical columns known as groups in the modern periodic table which are arranged from left to right and seven horizontal rows which are known as periods.The modern periodic table of elements can be broken down into 4 blocks – the s-block, the p-block, the d-block, and the f-block. This classification is based on the types of orbitals that contain the valence electrons of the element. For example, s-block elements have valence electrons in s-orbitals and d-block elements have their valence electrons in d-orbitals.