Question

What is the name for the horizontal rows of the periodic table?
1.Groups
2.Periods
3.Families
4.Sets

Answer 1

Hint:Periodic table is helpful in the organisation of elements and for us to understand the reactivity of each element and trends. The general properties of elements can be predicted with their location on the periodic table. It helps us to differentiate between metals, nonmetals and metalloids. There are various elements grouped together due to their nature of having similar properties.

 Complete step-by-step answer:One such grouping is of lithium, sodium, and potassium. the unique properties which they have in common is that they all are shiny and known to conduct heat and electricity very well. Their chemical properties are similar too as they lie in the same group, which is the vertical row. A second grouping includes calcium, strontium, and barium. The first group is known to be more reactive that the second group. This is because the first group has only one electron to lose during reactions which can be lost easily.
 When we talk about the horizontal rows present in the periodic table, we name these rows are period. There are a total of seven periods in the periodic table, and each one begins at the far left. With a new principal energy level beginning to fill with electrons, there is an establishment of a new period.
There are only two elements present in Period $1$ (hydrogen and helium), while periods $2$ and $3$ have $8$ elements. Periods $4$and $5$ have $18$ elements. Periods $6$and $7$ have $32$ elements. This is because the two bottom rows which are separated from the rest of the table belong to those periods.

Answer is Periods \[\left( 2 \right)\].

Note:When we talk about group seven, it consists of halogens. Chlorine, fluorine and bromine fall under this group and have properties different than those of the first and second group. This is because they have seven electrons present in their valence shells. Period $6$and $7$are pulled out in order to make the table itself fit more easily onto a single page.