Question

What does periodic mean?

Answer 1

The elements present on the periodic table repeat intervals are known as periods. Elements having the same group will also have the same properties and will also react in the same manner. This was given by the scientist mendeleev.

Complete step by step answer:
In terms of chemistry and periodic table, a period is a row of chemical elements. There elements in a row will have the same number of electron shells. The element next to it in a period will have one more proton and is known to be less metallic than the element before. The arrangement is done in such a way; the group of elements in the same column have the same chemical as well physical properties, showing the periodic law.
Example; the halogen is placed in the second last column .i.e. group $17$ which shows the properties such as high reactivity and a tendency to gain one electron to arrive at a noble gas electronic configuration.
The explanation given by modern quantum mechanics says that these periodic trends in terms of electron shells. As the atomic number increases, the shell fills up with electrons in the form of an ordering rule diagram. This filling of each shell indicates a row in the periodic table.
The elements in the s-block and p-block have similar periods and generally do not exhibit trends and similarities in properties. However, when it comes to d-block, the trend across periods becomes significant, and the f-block elements have high degree of similarity across the period.

Note:
According to $2021$ data there are a total of $118$ elements that have been discovered and also are confirmed. Periodicity is the trend or the recurring variations in element properties with an increase in atomic number. This periodicity is caused due to the regular and predictable variations in element atomic structure.