In the periodic table, the elements that are adjacent to the "stair step" are called actinide series nonmetals metalloids alkali metals

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Metalloids

Explanation:-

The stair step line is a line in the periodic table that divides the metals on one side and the non metals on the other side. So the elements which lie on the stair step line must have properties in between those exhibited by the metals and those by the non metals.

Such elements we know are called metalloids. Thus In the periodic table, the elements that are adjacent to the "stair step" are called metalloids.

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