Hydrogen can be placed in group 1 and group 17 of periodic table. Why?
Hydrogen can be placed in group 1 and group 17 of periodic table. Why?
The resemblance of hydrogen with alkali metals (Group -1):
1. Electronic configuration:- like alkali metals hydrogen also contains one electron in its outermost shell. Example: H-1, Li-2,1
2. Electropositive character:- like alkali metals(Na+,K+) hydrogen also loses its only one electron to form hydrogen ion,H+
3. Oxidation state:-like alkali metals hydrogen exhibits an oxidation state of +1 in its compounds. Example =HCl, NaCl
4. Combination with non-metals:- like alkali metals hydrogen combines with non-metals such as oxygen and sulphur forming their oxides and sulphides. Example H2OlikeNa2O,K2O
5. Like alkali metals hydrogen also act as a strong reducing agent.
The resemblance of hydrogen with halogens (Group -17):
1. Electronic configuration:- All halogens have 7 electrons in their respective outermost shell and thus have one less electron than the stable configuration of nearest noble gas Hydrogen on the other hand has one electron less than the stable configuration of nearest noble gas i.e. Helium
2. Electronegative character:-Halogens have a strong tendency to gain one electron to form halide ions, In a similar way hydrogen shows some tendency to gain one electron to form hydride ion.
3. Oxidation state:- Just like halogens hydrogen shows an oxidation state of -1. Like halogens, hydrogen easily combines with nonmetals such as carbon, silicon,nitrogen, etc to form covalent compounds.Examples: CH4
Thus, it can be placed both in group 1 and group 17.
The resemblance of hydrogen with alkali metals (Group -1):
1. Electronic configuration:- like alkali metals hydrogen also contains one electron in its outermost shell. Example: H-1, Li-2,1
2. Electropositive character:- like alkali metals(Na+,K+) hydrogen also loses its only one electron to form hydrogen ion,H+
3. Oxidation state:-like alkali metals hydrogen exhibits an oxidation state of +1 in its compounds. Example =HCl, NaCl
4. Combination with non-metals:- like alkali metals hydrogen combines with non-metals such as oxygen and sulphur forming their oxides and sulphides. Example H2OlikeNa2O,K2O
5. Like alkali metals hydrogen also act as a strong reducing agent.
The resemblance of hydrogen with halogens (Group -17):
1. Electronic configuration:- All halogens have 7 electrons in their respective outermost shell and thus have one less electron than the stable configuration of nearest noble gas Hydrogen on the other hand has one electron less than the stable configuration of nearest noble gas i.e. Helium
2. Electronegative character:-Halogens have a strong tendency to gain one electron to form halide ions, In a similar way hydrogen shows some tendency to gain one electron to form hydride ion.
3. Oxidation state:- Just like halogens hydrogen shows an oxidation state of -1. Like halogens, hydrogen easily combines with nonmetals such as carbon, silicon,nitrogen, etc to form covalent compounds.Examples: CH4
Thus, it can be placed both in group 1 and group 17.
