Question

How are the relationships of elements in a group different from the relationships of elements in a period?

Answer 1

The periodic table is defined as a tabular array of the chemical elements organized by atomic numbers, from the element starting with the lowest atomic number, hydrogen, to the element with the highest atomic number, oganesson.

Complete answer:
A periodic table consists of seven horizontal rows and 18 vertical groups.
ELECTRONIC CONFIGURATION OF ELEMENTS AND THE PERIODIC TABLE:
We know that an electron in an atom is characterised by a set of four quantum numbers (n, I, m and s) where the principal quantum number (n) defines the main energy level known as the shell. We have also studied about the filling of electrons into different subshells (s, p, d and f) in an atom. This distribution of electrons into various subshells of an atom is called its electronic configuration. The atomic number of an element is defined as the number of protons present in the nucleus of an atom of that element. The location of any element in the periodic table is reflected by the quantum numbers of the last orbital filled. Here we will discuss the direct relation between the electronic configuration of the element and its location in the periodic table.
The period indicates the value of n for the outermost or valence shell. In other words, a successive period in the periodic table is associated with the filling of the next higher principal energy level like n = 1, n = 2, n = 3. refers to the filling of the first, second, third and higher principal energy levels.
Now, the vertical columns are called groups and they are done so in order to show the similarity in the chemical behaviour. Whereas, the horizontal rows, which are the periods, are classified so as to show the difference in the elements, as the periods increase, the shell r=number remains same, whereas the electrons number increases.

Note:
It can be readily observed that the number of elements in each period is twice the number of atomic orbitals available in the energy level that is being filled.