What is meant by periodicity of properties?

Explanation

**Step-by-Step Text Solution:**

1. **Definition of Periodicity of Properties**: The term "periodicity of properties" refers to the recurring trends or patterns observed in the properties of elements as you move across the periodic table.

2. **Repetition of Properties**: In the periodic table, certain properties of elements tend to repeat at regular intervals. This means that elements in the same group (vertical column) often exhibit similar chemical and physical properties.

3. **Example from the Periodic Table**: For instance, if we look at the noble gases (like helium, neon, argon), we can see that they share common characteristics such as being colorless, odorless, and having very low reactivity. Similarly, alkali metals (like lithium and sodium) also display similar properties, such as being highly reactive and having one electron in their outer shell.

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