Hydrogen shows properties of both group 1 and group 17.

Here are some properties of hydrogen.

1. Resemblance with alkali metals:-
   1. Electronic configuration: Hydrogen like alkali metals has one electron in it's valence shell.
   2. Electropositive character: Hydrogen like alkali metals is electropositive because it can lose one electron readily to form hydrogen ion (H+).
   3. Valency and oxidation state: Like alkali metals hydrogen also shows an oxidation state of +1 in it's compounds.
   4. Combination with electronegative elements: Like alkali metals, hydrogen forms binary compounds with electronegative elements such as halogens, oxygen, and sulfur.
   5. Liberation at cathode: When the fused salts of alkali metals are electrolysed, metal ions are liberated at the cathode. In a similar manner, hydrogen is liberated at the cathode on subjecting the aqueous solutions of it's salts to electrolysis.
   6. Reducing agent: Like alkali metals, hydrogen acts as a strong reducing agent.
2. Resemblance with halogens:-
   1. Electronic configuration: Like halogens hydrogen has only one electron less than the nearest Noble gas configuration.
   2. Ionisation enthalpy: The ionisation enthalpy of hydrogen is quite close to that of halogens.
   3. Electronegative character: Hydrogen like halogens had tendency to accept electron to form monovalent anion. By accepting an electron hydrogen as well as halogens acquire Noble gas configuration.
   4. Oxidation state: Like halogens hydrogen exhibits oxidation state of -1 in it's compounds.
   5. Diatomic nature: Hydrogen molecule (H2) is diatomic like halogens molecules (F2,Cl2,Br2,I2).
   6. Liberation at anode: When fused with alkali metal hydrides such as lithium or sodium hydride is electrolysed hydrogen is liberated at the anode. This is in the same way as halogens are liberated at anode when fused with alkali metal halides are electrolysed.
   7. Non-metallic character: Like halogens hydrogen is non-metallic in nature.
   8. Nature of compound: Like halogens hydrogen combined with non-metals such as carbon, silicon, germanium, etc. to form covalent compunds.