Chemical reactivity
The ability of a substance to react
chemically is called chemical reactivity.
Explanation: During chemical reactivity the
molecules come closer and combine through bonds and formed new compounds. It
can react in three ways
- By giving electrons
- By accepting electrons
- By sharing electrons
Electro positive character of metal.
The property of element to lose
electrons and form a positive ions is called electro positivity or electro
positive character of metal.
Electro positive character across the period
The
electro positive character of metal is decreasing across the period due to
increase of electrons in same shell mean increase in electro negativity.
Electro positive character down the group
The
electro positive character of metal is increasing down the group due to
addition of more shells and also in size of an atom.
Inertness and uses of noble metals
Inertness of noble metals
The noble metals which are
unreactive due to having stable electronic configuration is called inertness of
noble metals.
Explanation: The noble metals are used
in jewelry because noble metals are unreactive and cannot tarnish even after a
long time.
Uses of noble metals
- Noble metals are used in jewelry.
- Noble metals are used in making of photographic films.
- Noble metals are used also in dental filling with some other compounds.
- Noble metals is used as a catalyst in many reactions.
- It is used to change the toxic gases.
- It is also used in LCDs, CDs and hard disk of many computers.
- It is also used in many electronic parts.
Uses of non-metals
The used are as follow
- Unlike metals, non-metals are poor conductor of heat and electricity.
- Solid non-metals are dull and brittle except iodine.
- Unlike metals, non-metal are used to form acid oxides.
- Non-metals have low densities.
- Non-metals have low melting and boiling points.
- Non-metals have high electronegativities.
- Non-metals can be used as a insulators.
Comparison of reactivity of halogens.
In the periodic table the elements of
group 17 is called halogens. All halogens exist in di atomic form. In halogens
fluorine and chlorine are gases while bromine and iodine are liquid and other
are solid respectively. Halogens are the most electronegativity and most
reactive elements in the periodic table. Both electronegativity and reactivity
of halogens is decreasing down the group. Halogens electronic configuration
exists in ns2, nP5 where n shows number of shells. Thus
there are 7 electrons in their outermost shells and need one electrons for
their existence. Halogens can form both ionic and covalent bind.
Some reactions of halogens
Reaction with hydrogen
F2
+
H2 è 2HF
+
energy
Reaction with chlorine gas
Cl2 + H2
è 2HCl
Reaction with Br2
Br2 + H2
è 2HBr
Reaction with I2
I2
+ H2 è 2HI
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