What are groups and periods in the modern periodic table?

Short/Brief Note

The horizontal rows are called periods. There are seven periods in the periodic table.
Vertical columns in the periodic table starting from top to bottom are called groups. There are 18 groups in the periodic table.

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Chapter 12: Periodic Classification of Elements - Exercise [Page 146]

Chapter 12 Periodic Classification of Elements
Exercise | Q VI. 2. | Page 146

State modern periodic law.

Consider the following elements:
Na, Ca, Al, K, Mg, Li

Which of these elements belong to the same group of the periodic table?

What happens to the number of valence electrons in the atoms of elements as we go down in a group of the periodic table?

In the modern Periodic Table, why does cobalt with higher atomic mass of 58.93 appear before nickel having lower atomic mass of 58.71?

Give the symbol and valency of the following element and radical.

Potassium

Give the symbol and valency of the following element and radical.

Calcium

Which of the following statements about the Modern periodic table is correct?

Mendeleev's periodic table : atomic mass : : Modern periodic table : _______

Distinguish between:

s-block - p-block

An element has 2 electrons in its N shell.

State its position in periodic table.