Question

What is meant by periodic trend? Define atomic size.how does it very in a period and group.

Answer 1

A periodic trend is a regular variation the properties of an element with increasing atomic number. A periodic trend is attributed to regular variation in the atomic structure of each element.
Atomic size is the distance between a nucleus of an atom and its valence or outermost shell. Atomic size is a very important characteristic of an atom to understand the reactivity.
Atomic size decreases across a period from left to right, but increase down a group, a column of periodic table

Answer 2

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When the properties of elements in a period or a group of the modern periodic table are compared, certain regularity is observed in their variations. It is called the periodic trends in the periodic table. The periodic trends is observed in properties of elements, namely, valency, atomic size, and metallic character.

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