Question

write about the modern periodic table. explain the characteristics of groups and periods​

Answer 1

The long form of periodic table consist of vertical columns called groups and horizontal rows called periods.

Elements are arranged in the increasing order of atomic numbers.

Elements in the modern periodic table are arranged in 7 periods and 18 groups.

Horizontal rows are called periods and vertical columns are called groups.

Elements are placed in periods based on the number of shells in their atoms.

The shortest period is the first period which contains only two elements – Hydrogen and Helium.

The second period contains elements from Lithium to Neon.

The third period contains elements from Sodium to Argon.

The fourth period contains elements from Potassium to Krypton.

The fifth period contains elements from Rubidium to Xenon.

Sixth period is considered as the longest periods in the periodic table. It contains elements from Cesium to Radon

Seventh period is incomplete period

In group IIIB of the sixth period Lanthanides are placed.

In group IIIB of the seventh period Actinides are placed

In periodic table Lanthanides and Actinides are shown in the bottom of the periodic table.

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Answer 2

A periodic table is still used today to organize the elements.The modern table is based on Mendeleev's table, except the modern table arranges the elements by increasing atomic number instead of atomic mass.

A period is a horizontal row of the periodic table. There are seven periods in the periodic table, with each one beginning at the far left. A new period begins when a new principal energy level begins filling with electrons. Period 1 has only two elements (hydrogen and helium), while periods 2 and 3 have 8 elements.