10th Class Science Metals and Non-metals / धातु और अधातु Reactivity Series of Metals

       Reactivity Series of Metals

It is the arrangement of metals in a vertical column in the decreasing order of their reactivity. This is also known as reactivity series of metals.

\[K>Na>Ca>Mg>Al>Zn>Fe>Ni>Sn>Pb>H>Cu>Hg>Ag>Au>Pt\]

            Advantages of Reactivity Series

• It helps to compare the reactivity of given metals. The one which is placed higher in the reactivity series are more reactive than those placed lower in the series.
• It helps to know if the metal will react with dilute acid to liberate hydrogen gas or not.
• It helps in deciding suitable method for extraction of metals from their ores.

              Chemical Properties of Metals

• Reaction of Metals with Salt Solution

More reactive metal displaces a less reactive metal from its salt solution.

e.g.   \[Fe+CuS{{O}_{4}}\to FeS{{O}_{4}}+Cu\] (Iron is more reactive than copper)

(Blue)                    (Green)

\[Ag+CuS{{O}_{4}}\to NO\] reaction (Silver is less reactive than copper so it cannot displace it.)

• Reaction of Metals with Non-metals

Metals react with non-metals to form ionic compound.

e.g.   \[2Na+C{{l}_{2}}\to 2NaCl\] and  \[Ca+{{F}_{2}}\to Ca{{F}_{2}}\]

Ionic compounds are the compounds formed by losing and gaining of electrons.

e.g.         \[Na+Cl\to \,\,[N{{a}^{+}}]\,\,{{[Cl]}^{-}}\,\to \,NaCl\]

• Reaction of Metals with Hydrogen

Metals react with hydrogen to form metal hydrides. But only reactive metals like sodium, potassium and calcium form their hydrides.

\[2Na+{{H}_{2}}\to 2NaH\]          and        \[Ca+{{H}_{2}}\to Ca{{H}_{2}}\]

• Metals act as reducing agents, it is because they can donate electrons and themselves get oxidized.

e.g.        \[2Al+F{{e}_{2}}{{O}_{3}}\to A{{l}_{2}}{{O}_{3}}+2Fe\]

 \[Al\to A{{l}^{3+}}+3{{e}^{-}}\]

          Chemical Properties of Non-metals

• Non-metals are electro negative in nature, i.e. they can accept electrons and form anions.

\[S+2{{e}^{-}}\to {{S}^{2-}}\]         and           \[F+{{e}^{-}}\to {{F}^{-}}\]

(2,8,6)    (2,8,8)                                  (2,7)    (2,8)

• Non-metals react with oxygen to form acidic oxides which turn red litmus blue.

\[S+{{O}_{2}}\to S{{O}_{2}},\]    \[{{N}_{2}}+{{O}_{2}}\to 2NO\]                 and        \[{{N}_{2}}+2{{O}_{2}}\to 2N{{O}_{2}}\]

Here, NO (nitric-oxide) is neutral, while N0^ (nitrogen dioxide) is acidic.

• Non-metal do not react with dilute acids to liberate hydrogen gas. It is so because non - metals are less reactive than hydrogen and so they cannot displace hydrogen from mineral acids.
• Non-metals react with hydrogen to form their hydrides which are covalent in nature.

\[{{N}_{2}}+3{{H}_{2}}\to 2N{{H}_{3}}\]

\[{{H}_{2}}+S\to {{H}_{2}}S\]

• Non-metals react with chlorine to form covalent chlorides.

e.g.:   \[2S+C{{l}_{2}}\to SC{{l}_{2}}\], (Sulphurs chloride) and \[{{P}_{4}}+6C{{l}_{2}}\to 4PC{{l}_{3}}\]

Non-metals act as oxidizing agent as they have 5,6 or 7 valence electrons. They can therefore accept electrons to complete their octet.

            Properties of Metalloids

• They have metallic lustre.
• They are good conductors of electricity.
• They can form alloys.
• They form stable hydrides.
• Their chlorides are covalent in nature.

e.g. Silicon, germanium/ arsenic, antimony, tellurium.

          Sulphur is burnt in air and the gas produced is dissolved in water. The solution will

(a) Turn blue litmus red                                

(b) Gives no colour with phenolphthalein

(c) Form salt and water with sodium hydroxide

(d) All of these

(e) None of these

Answer: (d)

      The correct order of activity series is:

(a) \[K,\,\,Ca,\,\,Pb\]

(b) \[Ca,\,\,K,\,\,Pb\]

(C) \[K,\,\,Pb,\,Ca\]

(d) \[Pb,\,\,K,\,\,Ca\]

(e) \[Pb,\,\,Ca,\,\,K\]

Answer: (a)