Question

The element with atomic number 118, if discovered will be placed in:
A.1st group
B.14th group
C. 16th group
D. 18th group

Answer 1

The modern periodic table is based on the law that physical and chemical properties of elements in the periodic table are the periodic function of their atomic numbers. The elements in a periodic table are arranged according to atomic numbers, in vertical groups and horizontal periods.

Complete answer:
The modern periodic table consists of various elements arranged in order of increasing atomic number. With increase in each atomic number the shells and orbitals also get filled. The filling takes place according to aufbau principle from s, p, d, and f orbitals. These filling of electrons in the orbitals tell us the electronic configuration of elements. Elements that have these orbitals fully filled are placed with the noble gases in group 18. While elements with only one electron in the outer shell are placed in the first group. They are known as metals.
The element with atomic number 118 has the electronic configuration, $[Rn]5{{f}^{14}}6{{d}^{10}}7{{s}^{2}}7{{p}^{6}}$ , since all of the shells are fully filled, this element will be placed with the noble gases in group 18.
The name of element with atomic number 118 is oganesson (Og), which is a reactive and artificially produced element, and is radioactive.
Hence, the element with atomic number 118 is placed in the 18th group.

So, option D is correct.

Note:
The shell s can accommodate 2 electrons, p can have 6 electrons, d can have 10 electrons, and f can have a total 14 electrons. To round up the electronic configuration of elements with greater atomic numbers, a noble gas covering the number of electrons as the atomic number of the gas is written, here radon (Rn) with atomic number 86 is written and then the remaining 32 electrons are filled in their shells making the atomic number 118.