Page 1 - Microsoft Word - Lesson note-HYDROGEN

HYDROGEN

Key notes:

1.Hydrogen-occurrence, Isotopes, Preparation, Properties and uses
2.Hydrides-ionic covalent and interstitial
3.Physical and Chemical Properties of water
4.Hydrogen peroxide
5.Hydrogen as a fuel

Occurrence:
It is the most abundant element in the universe. It is rarely found in the free
state in the earth’s atmosphere. However, in the combined state, it is the third
most abundant element on the earth’s surface.

Isotopes of Hydrogen:
Hydrogen has three isotopes: protium (1H ), deuterium (D or 1H ) and tritium (T
1
2
3
or 1H ). Amongst these three, only tritium is radioactive. In spite of its
resemblance both with alkali metals and halogens, it occupies a separate
position in the periodic table because of its unique properties.
Properties:
Hydrogen is the lightest atom with only one electron. Loss of this electron
results in an elementary particle, the proton. Thus, it is unique in character.

Hydrogen resembles both with alkali metals and halogens. It occupies separate
position in the periodic table because of its unique properties.

Hydrogen is a colourless, odourless and a tasteless gas. It is non-metal and
diatomic. It is slightly soluble in water. Hydrogen should be handled with care
as it is highly combustible.

Resemblance with alkali metals:

+
+
+
 Show electropositive character: H , Na , K , etc.
 It shows oxidation state of +1
 It forms binary compounds with electronegative elements like alkali
metals.

 It reacts with halogens to form halides: HCl, NaCl, KCl, etc.