The first noble gas in the periodic table is:
(1) Helium
(2) Hydrogen
(3) Argon
(4) Neon
The Correct answer and Explanation is:
The correct answer is (1) Helium.
Helium (He) is the first noble gas in the periodic table, occupying the atomic number 2. Noble gases are a group of chemical elements characterized by their lack of reactivity due to having full valence electron shells. This stability makes them less likely to form compounds with other elements compared to other groups of elements.
Helium is located in Group 18 of the periodic table, which includes all noble gases such as neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Its position in the periodic table reflects its electronic configuration, which is 1s². This configuration indicates that helium has two electrons, filling its only electron shell. As a result, it achieves a stable electron configuration similar to that of the much heavier noble gases.
In contrast, hydrogen (H), with atomic number 1, is not a noble gas; it is a non-metal that behaves differently from the other elements. Hydrogen has only one electron in its outer shell, making it highly reactive as it seeks to achieve a full shell through chemical bonding. Argon and neon, while also noble gases, are positioned after helium in the periodic table. Argon, for instance, has atomic number 18 and possesses a complete octet of electrons, making it stable, but it is not the first noble gas.
The uniqueness of helium lies in its applications and properties. It is commonly used in balloons, as a cooling medium in cryogenics, and in various scientific applications due to its inertness and low boiling point. Helium’s lightness and non-flammability make it a safer alternative to hydrogen in many scenarios, further emphasizing its significance among noble gases.