How did mendeleev organize the elements to create a periodic table

By definition, Mendeleev's periodic table was rearranged according to atomic number, hence there are 7 periods (rows) and 18 groups (columns)

Mendeleev proposed to arrange the elements in lines and columns (also called "periods" and "groups") within a rectangle, with their atomic weights in ascending order from left to right within the same line down to the second and so on.

In other words, the elements are ordered by atomic number, which is defined as the number of protons found in the nucleus.

Also, Mendeleev showed that elements with similar chemical properties appeared periodically, giving rise to eight groups.

In this way he reorganized the periodic table leaving holes where an element did not exist, so that it can be discovered.

Finally, in summary, Mendeleev's periodic table was rearranged according to atomic number, hence there are 7 periods (rows) and 18 groups (columns).

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electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia