Hydrogen - Position in the Periodic Table

Dhristi JEE 2022-24

Introduction to the Position of Hydrogen in Periodic Table

Hydrogen is defined as the first element of the periodic table because its atomic number is 1, which means it contains only one single electron in its atom. Therefore only 1 electron is available in its outermost shell. The elements' placement in the periodic table is according to their electronic configuration.

 

One of the smallest and the first element of the periodic table is hydrogen. This hydrogen element is widely used not only in industries but also in various daily life materials that are used. Hydrogen has a lot of properties that are similar to a lot of the elements in the periodic table. It is due to these similarities that are found that Hydrogen has a Position in The Periodic Table that is quite a different form above and is placed singly. With the wide number of properties, it is seen that Hydrogen is quite different from others while also showing a lot of similarities

Structure of Hydrogen

The structure of hydrogen is similar to that of alkali metals (ns1), which contains one electron in their outermost shell. Also, it can attain helium noble gas configuration by accepting an electron. This character is mostly the same as that of the halogen family (ns2, np5), and is also short of one electron for the completion of the electron octet in their shells.

 

When a hydrogen atom loses an electron and produces a cation, it resembles the alkali metals whereas, when it gains an electron and becomes a uni-negative ion, it represents similarity to the halogens. By taking a look at these properties, the position of hydrogen in the periodic table is the major question.

Hydrogen in the Periodic Table

Moving on to the formation of compounds, hydrogen produces oxides, sulphides, and halides resembling alkali metals. Whereas unlike the alkali metals, it contains a very high ionization enthalpy, and hence it lacks metallic characteristics under regular conditions. By looking in terms of the ionization enthalpy, it is found that hydrogen resembles more halogens compared to alkali metals. For example, ΔiH of lithium is given as 520 kJ mol-1, hydrogen is given as 1312 kJ mol-1, and for fluorine, it is given as 1680 kJ mol-1. It also exists as a diatomic molecule similar to that of halogens (for example, chlorine Cl2); a single hydrogen bond exists when the H2 molecule is formed.

 

Though hydrogen atoms exhibit a lot of resemblance to both alkali metals and halogens, both are very different. Thus, in the periodic table, great thought has to be given for the hydrogen position. When the hydrogen atom loses electrons, the size of its nucleus decreases and almost becomes 1.5 × 10-3 pm, which is much smaller when compared to the atomic sizes of the normal metals, and therefore the hydrogen ion does not freely exist in nature.

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

Generally, in the periodic table, Hydrogen does not have a fixed position. In a few tables, it is placed with alkali metals (which is above Sodium), and in a few others, it is lonely placed at the top (Randomly, Just above the first Period).

 

Hydrogen resembles the alkali metals in electronic configuration. Hydrogen atoms contain the re-configuration 1s1, and it is the first element to be placed according to the rule. It is also placed with the alkali metals because it can lose its one e- to form H+ simply such as the alkali metals. Whereas hydrogen atoms also resemble halogens. Alkali metals produce hydrides such as LiH and Nah, just similar to LiCl and NaCl. The electrolysis of hydrides produces H2, and the Electrolysis of NaCl yields Cl2. In addition, hydrogen can gain one electron, such as halogens, to produce a noble gas configuration (which is H-).

 

Because of its resemblance to halogens and alkali metals, its position is still not fixed. But conventionally, we keep it including the alkali metals.

Why is Hydrogen Placed in Both Periodic Table Groups?

Hydrogen holds one valence electron in its outermost shell, and therefore it contains similar chemical properties compared to alkali metals. Also, hydrogen exists as a diatomic molecule similar to halogens and produces compounds with both metals and nonmetals. Thus, the hydrogen molecule can be placed in both the 1st as well as 17th groups in the modern periodic table. This anomaly with the position of hydrogen was one of the biggest demerits of Mendeleev's periodic table.

 

However, considering the modern periodic table, the hydrogen molecule has been awarded the top position, which neither belongs to group 1 nor group 17.

Elements That Won’t Occur Naturally

Up to plutonium (having an atomic number of 94), all the periodic table elements are present on Earth, although many of them (namely promethium, technetium, polonium, francium, astatine, protactinium, plutonium, and neptunium) take place simply in tiny amounts, typically as the by-products of other’s radioactive decay. Their amounts are very tiny, up to a recent past, where those elements were given as not occurring naturally on Earth. As per the atomic numbers, which are higher than 94, all of the corresponding elements are artificial, and they do not occur naturally on Earth.

Importance of Hydrogen

The most important hydrogen in the human body function is to keep the body hydrated. Water contains oxygen and hydrogen and is absorbed by the cells of the body. Thus, it is defined as a crucial element that can be used as a military weapon, fuel, and more, but not in our bodies.

Facts About Hydrogen:

  1. It has an atomic number of 1

  2. It has the atomic symbol H

  3. Hydrogen has an atomic weight of 1.0079

  4. It has two oxidations states +1 and -1

  5. The elemental classification of hydrogen is non-metal.

History of Hydrogen:

Hydrogen has descended from a Greek word named Hydro which means water and Gennaro which means production. This in short means water producer. It was first found and isolated by Cavendish in the year 1766 when hydrogen was believed to be a lot of different things. Cavendish who found the element himself thought that it was an inflammable air from metals which gave proof to the production of Hydrogen by the action of acids on metals. Before this happened Robert Boyle and Paracelsus had both used iron and acids to generate hydrogen gas and Antoine Lavoisier gave hydrogen its name because it used to produce water when it was ignited in the air.

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FAQs (Frequently Asked Questions)

1. What is Special About Hydrogen?

Hydrogen is defined as the most abundant and simplest element in the universe. It consists of a single proton and electron. Liquid hydrogen can be used in the superconductors study and makes an excellent rocket fuel when combined with liquid oxygen. Several compounds are formed by the hydrogen molecule combined with other elements.

2. Explain whether Hydrogen is gas or metal?

Hydrogen is the compound, which is most often classified as a nonmetal because it has several properties of nonmetal. For example, at room temperature, this is a gas. In group 1, however, hydrogen shares the properties with alkaline metals. Hydrogen also conducts electricity in a liquid form, similar to what metal does.

3. Where is the Hydrogen molecule commonly used?

Hydrogen is used in the glass industry to make flat glass sheets as a protective atmosphere. It can also be used as a flushing gas in the electronics sector while manufacturing silicon chips. And, the density with low hydrogen made it a natural choice for one of its first practical applications, which is filling airships and balloons.

4. Give Two Chemical Properties of Oxygen?

Two element atoms bind to produce di-oxygen at the Standard Temperature and Pressure (STP), an odourless, colourless, tasteless diatomic gas having the chemical formula O2. Oxygen exists on the periodic table, which is a member of the chalcogen group and a highly reactive non-metallic element.

5. What are the Isotopes of Hydrogen and how do they differ from Hydrogen?

There are in total three isotopes of hydrogen which can be provided as follows:

  1. Hydrogen

  2. Deuterium

  3. Tritium

These are called to be isotopes as they have the same electronic configuration as hydrogen but will contain different molar masses due to the difference in the number of neutrons that are present. For example, hydrogen consists of one electron and there is no presence of neutrons while deuterium consists of the one-electron which is the basic configuration and will contain one neutron as well and tritium will contain one electron and two neutrons in them.

6. Can Hydrogen react with all elements in the periodic table or is it limited to only specific elements?

Hydrogen is a nonmetal that can easily react with a lot of elements and it also can form covalent bonds with a lot of elements. The reaction with various elements can be given as follows:

  1. Reaction of hydrogen with active metals:

Hydrogen which has a single electron tends to accept electrons from ionic hydrides that are present like LiH which provides hydrogen with a -1 charge that makes hydrogen behave as a halogen.

  1. Reaction of hydrogen with nonmetals:

Unlike the metals that form ionic bonds with nonmetals hydrogen will be much less electropositive than the active metals and hence forms covalent bonds.

7. How is Hydrogen similar to Alkali Metals?

The similarities of hydrogen to metals can be provided as follows:

  1. Electronic configuration: Like all the other elements Hydrogen will consist of one electron in its shell.

  2. Noble gas configuration: Just like alkali metals there is a need to lose one electron in its valence shell to achieve a stable configuration as that of the next noble gas which will be Helium. It will hence form a proton ion.

  3. Good reducing agent: Hydrogen is one of the reducing agents that are widely used just like other alkali metals.

  4. Forms halides: Just like alkali metals the hydrogen will combine with electronegative elements to form halides.

8. How is Hydrogen different from a halogen?

The differences between halogens can be provided as follows:

  1. Structure of atom:

Hydrogen will consist of only one electron in its outer shell while the halogen has seven electrons in its last shell.

  1. Size of atom:

The hydride ion is much larger than those ions of the halogens. This is seen as hydrogen only consists of one electron and a single proton. This makes the pull of the nucleus a bit less strong than those seen in halogens.

9. What are some of the applications of Hydrogen in Chemistry?

The majority of hydrogen that has been industrially produced is used in Haber’s process to manufacture ammonia. It is also widely used in the production of “water gas” from the reaction of coal with steam. All of these uses along with other uses makes it one of the widely used elements for various reactions and production of substances. Vedantu has also listed some of the other uses of hydrogen in daily life in the Vedantu NCERT Solution for Chemistry. 

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