Position of hydrogen in periodic table


Position of Hydrogen in Periodic Table: Introduction

Since hydrogen has only one electron in its atom, it is the first element in the periodic table. The outermost shell of the atom contains only one electron. According to their electronic configuration, elements are arranged in the periodic table and thus the position of hydrogen in periodic table is fixed. The first element of the periodic table and one of the smallest is hydrogen. In addition to being used in industries, this hydrogen element is also widely used in daily life.

 Some of the properties of hydrogen are similar to those of many elements in the periodic table. Obviously, because of these similarities, Hydrogen's position in The Periodic Table is quite a different form from above and is placed singly following different Trends in Periodic Table. There are a lot of similarities and differences between Hydrogen and other elements because of its wide range of properties.

Hydrogen Structure

Hydrogen's structure is similar to that of alkali metals (ns1), which have one electron in their outermost shell. The helium noble gas configuration can also be achieved by accepting an electron. They also lack one electron for the completion of the electron octet in their shells, as do members of the halogen family (ns2, np5). The hydrogen atom, when it loses an electron and forms a cation, resembles the alkali metals whereas, when it gains an electron and forms a uni-negative ion, it resembles the halogens. This leads to the question of where hydrogen fits in the periodic table based on its properties.

The Reason Behind Placing the Hydrogen Atom at First in the Periodic Table

Hydrogen does not have a fixed position in the periodic table. Several tables place it with alkali metals (above Sodium), and others place it alone at the top (randomly, just above the first period). The electronic configuration of hydrogen is similar to that of alkali metals. The hydrogen atom contains re-configuration 1s1, and it is the first element to be placed according to the rule.

Due to its ability to lose its one e-, it is also grouped with alkali metals. Halogen atoms also resemble hydrogen atoms. Just as LiCl and NaCl are produced by alkali metals, LiH and Nah are produced by alkali metals. When hydrides are electrolyzed, H2 is produced, and when NaCl is electrolyzed, Cl2 is produced.

Additionally, hydrogen has the ability to gain one electron, like halogens, in order to form a noble gas configuration (H-). Since it resembles halogens and alkali metals, its position remains uncertain. Conventionally, we include the alkali metals.

Why is Hydrogen Placed in Both Periodic Table Groups?

Due to its one valence electron, hydrogen has similar chemical properties to alkali metals. Hydrogen is also a diatomic molecule like halogens, and it can form compounds with metals and nonmetals. As a result, hydrogen belongs to both the 1st and 17th groups of the modern periodic table. In Mendeleev's periodic table, hydrogen's position was one of the biggest flaws. According to the modern periodic table, however, the hydrogen molecule occupies the top position, which is neither in group 1 nor in group 17.

Elements That Won’t Occur Naturally

As far as plutonium (atomic number 94) is concerned, all the elements from the periodic table exist on Earth, although most of them (namely promethium, technetium, polonium, francium, astatine, protactinium, plutonium, and neptunium) occur in tiny amounts, usually as a result of the radioactive decay of others. Until recently, those elements were not considered to occur naturally on Earth due to their extremely small amounts. All elements with atomic numbers higher than 94 are artificial, and they do not occur naturally on Earth.




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