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.