Chapter 6. Study of the First Elements

Position of Hydrogen in the Periodic Table

* Hydrogen is the first element in the periodic table.

* The atomic number of hydrogen is one.
* Hydrogen has only one electron in the k-shell of its atom.
* Hydrogen has a dual nature; it resembles the alkali metal as well as the halogens.
* Like alkali metals, hydrogen has one electron in its valence shell.
* Hydrogen burns in oxygen to form water.
* Hydrogen combines with non – metals such as oxygen, sulphur and chlorine to form water, hydrogen sulphide and hydrogen chloride.
* Hydrogen has the tendency to form a cation by losing an electron.
* Hydrogen acts as a reducing agent.
* Hydrogen is a non – metal.
* Hydrogen exists as a diatomic molecule
* Hydrogen has the tendency to for anions.
*British scientist Henry Cavendish discovered hydrogen.
* It is the most abundantly found element in the universe.

Preparation of Hydrogen

* The reaction of acids with sodium, potassium and calcium is violent, while the reaction with Zinc, iron, aluminium and magnesium is smooth.
* The rate of reaction of metals determines their activity series.
* The metals above hydrogen in the activity series react with dilute sulphuric acid and dilute hydrochloric acid to liberate hydrogen.
* Hydrogen can be obtained by the action of concentrated alkali solution on some metals such as aluminium, zinc and tin.
* Hydrogen is prepared in a laboratory by the action of dilute sulphuric acid or dilute hydrochloric acid on zinc granules.
* Hydrogen is the lightest element in the periodic table.
* Hydrogen Cavendish discovered in the 18th century.
* Hydrogen is a colourless, odourless and tasteless and is neutral in nature.
* Hydrogen is used as a fuel.

Hydrogen can be prepared by:

    *  The action of metals on dilute acids, alkaline solutions and steam, Electrolysis of water.
    * Hydrogen is manufactured in large amounts by the Bosch process, electrolysis of water and partial oxidation of nature gas.
    *  Hydrogen gives a wide range of products with oxygen, nitrogen, sulphur, halogen and metals.

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