Topic: Alkali metals and Alkaline Topic: Alkali metals and Alkaline metalsmetals

AKM A- FormAKM A- Form

Chapter - Metallurgy

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Alkali MetalsAlkali Metals

The elements such as Lithium (Li), sodium (Na), The elements such as Lithium (Li), sodium (Na), potassium(K), rubidium(Rb),Cesium (Cs) and potassium(K), rubidium(Rb),Cesium (Cs) and francium(Fr) have one electron in their outermost francium(Fr) have one electron in their outermost shell shell so they are placed in IA group of the periodic table.so they are placed in IA group of the periodic table.

They react with water to form their hydroxides which are They react with water to form their hydroxides which are strong alkalis.strong alkalis.

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Position of Alkali metals in group Position of Alkali metals in group IAIA

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Characteristics of alkali metalsCharacteristics of alkali metals

1.Occurance : All of them are very reactive and do not occur in free state.

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Characteristics of alkali metalsCharacteristics of alkali metals

2. Nature: They are soft and can be cut with a 2. Nature: They are soft and can be cut with a knife and have low melting and boiling points.knife and have low melting and boiling points.

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Characteristics of alkali metalsCharacteristics of alkali metals

3. Bonding: All alkali metal salts are ionic in 3. Bonding: All alkali metal salts are ionic in nature.nature.

e.g. NaCl, KBr, LiCl, e.g. NaCl, KBr, LiCl,

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Characteristics of alkali metalsCharacteristics of alkali metals

4. Action of Air : They react rapidly with oxygen 4. Action of Air : They react rapidly with oxygen and water vapour in the air. Reactivity and water vapour in the air. Reactivity increases down the group.increases down the group.

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Characteristics of alkali metalsCharacteristics of alkali metals

5.Action of water: They react violently with 5.Action of water: They react violently with water and produce hydrogen.water and produce hydrogen.

2M + H2M + H22O O 2MOH + H 2MOH + H22

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Characteristics of alkali metals Characteristics of alkali metals

6.Action of acids: They react violently with acids, dil HCl 6.Action of acids: They react violently with acids, dil HCl and Dil Hand Dil H22SOSO44 to produce hydrogen gas. to produce hydrogen gas.

2M + 2HCl 2M + 2HCl 2MCl +H 2MCl +H22

CLICK

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Alkaline Earth MetalsAlkaline Earth Metals

The elements such as Beryllium, magnesium, The elements such as Beryllium, magnesium, calcium, strontium and barium and radium are known calcium, strontium and barium and radium are known as alkaline earth metals because their oxides occur in as alkaline earth metals because their oxides occur in the earth’s crust and their hydroxides are alkalies.the earth’s crust and their hydroxides are alkalies.

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Characteristics of Alkaline earth Characteristics of Alkaline earth metalsmetals

1.Occurrence: They are reactive 1.Occurrence: They are reactive metals (less reactive than alkali metals (less reactive than alkali metals); hence they also do not metals); hence they also do not occur in free in nature.occur in free in nature.

They have two electrons in their They have two electrons in their last shell so they are placed in last shell so they are placed in group IIA of the Periodic table.group IIA of the Periodic table.

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Alkaline Earth MetalsAlkaline Earth Metals

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Characteristics of Alkaline earth Characteristics of Alkaline earth metalsmetals

2.Nature: They are grayish white in colour and 2.Nature: They are grayish white in colour and harder than alkali metals.harder than alkali metals.

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Characteristics of Alkaline earth Characteristics of Alkaline earth metalsmetals

3.Bonding: All the alkaline earth metal salts 3.Bonding: All the alkaline earth metal salts except beryllium are ionic compounds.except beryllium are ionic compounds.

e.g. MgO, CaCle.g. MgO, CaCl2,2, MgCl MgCl2.2.

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Characteristics of Alkaline earth Characteristics of Alkaline earth metalsmetals

4.Action of air: They are less reactive than alkali 4.Action of air: They are less reactive than alkali metals.metals.

Their reactivity increases on moving down the Their reactivity increases on moving down the groupgroup

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Characteristics of Alkaline earth Characteristics of Alkaline earth metalsmetals

5.Action of water: They react with water to 5.Action of water: They react with water to produce hydrogen.produce hydrogen.

M + 2HM + 2H22O O M(OH) M(OH)22 + H + H2 2

M is any alkaline earth metal. Ba reacts most M is any alkaline earth metal. Ba reacts most

vigrously with water.vigrously with water. Click

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Characteristics of Alkaline earth Characteristics of Alkaline earth metalsmetals

6. Action of acids: They react with dil HCl and6. Action of acids: They react with dil HCl and

dil Hdil H22SOSO44 to produce hydrogen. to produce hydrogen.

M + 2HCl M + 2HCl MCl MCl22 + H + H22

M + HM + H22 SO SO44 MSO MSO44 + H + H2 2

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AssessmentAssessment

1. Why are alkali metals kept in water?1. Why are alkali metals kept in water? 2. Which metal reacts with cold water 2. Which metal reacts with cold water

violently?violently? 3. Alkali metal salts are _________ 3. Alkali metal salts are _________

(ionic/covalent) in nature.(ionic/covalent) in nature.

4. Reactivity of alkali metals ____________ 4. Reactivity of alkali metals ____________

down the group (increases/decreases/remains down the group (increases/decreases/remains

same)same)1818

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