S - Block Elements:
Periodic table alkali and alkaline earth metals are S block elements,they are present extreme left hand side of periodic table so they are mostly metals( right side of periodic table elements are nonmetals) .They are away from Florin so their electronegative is very less. they are ready to give electrons so involve in ionic bond. valency electrons are from S -orbital ,so their name is S block elements,they posses ground state of energy levels. These are more reactive , so we are not able to get free elements in state combined form with halide, sulphate, carbonate, silicate ions, etc ,magnisum and aluminum form alloy.
IA and 11A both are comes under S-block elements. valency electrons are
Alkali metals :
lithium,
sodium,
potassium,
rubidium,
cesium,
and francium.
Group I A in periodic table.
They have valency electron 1 , they are not form free state in nature. they are ready to react with oxides and hydroxides gives strong hydride and oxide form . example NaOH,
And KOH.
They ready to give electron and form noble gas configuration. .
Atomic Radii: All Alkali metals have more atomic radii .
Ionic Radii: Is less in alkali metals because they have less number of shells
Density:
densities are lower than, those of other metals. Moving down Density increases.
Ionization energy: Alkali metals have low ionization energy
Melting and boiling points : low ,decreased to moving down
oxidation state : +1
Flame colour :Li - crimson red
Na - yellow
k - Violet
Rb - Red violet
Cr - Blue.
Alkali metals are with low ionization energies so they are more reactive ,they are ready to loss outer most one electron .these are have low electronegative ,so these are readily react with nonmetals ,specially halogens.
Oxides of alkali metals:many metals burn rapidly when heating in presence of oxygen and produces their oxides.
Group 1 metals react with oxygen to produces ionic oxides ,peroxides and super oxides.
oxides : 2 metal atoms with i oxygen atom , oxidation state is -2
4Li2 + O2 -à 2Li2 O
peroxide 2metal atom react with two molecules of oxygen, oxidation state is+1,peroxides are diamagnetic nature.
super peroxides 1 metal atoms react with 2 oxygen molecule,oxidation state is -1/2, super peroxides are paramagnetic nature.
Oxides ,peroxides and super peroxides are basic in nature, basicity increases from top to bottom ,Li<Na<K<Cr.
Periodic table alkali and alkaline earth metals are S block elements,they are present extreme left hand side of periodic table so they are mostly metals( right side of periodic table elements are nonmetals) .They are away from Florin so their electronegative is very less. they are ready to give electrons so involve in ionic bond. valency electrons are from S -orbital ,so their name is S block elements,they posses ground state of energy levels. These are more reactive , so we are not able to get free elements in state combined form with halide, sulphate, carbonate, silicate ions, etc ,magnisum and aluminum form alloy.
IA and 11A both are comes under S-block elements. valency electrons are
nS1, n S2
Properties of S-block elements:
- The small size of the atom and its ion.
- The high ionization energy and electronegativity.
- The non-availability of 'd' orbitals.
1. Physical StateAll elements are silvery or greyish white, soft and light metals.
2. Atomic SizeThe values of atomic and ionic size reveal that alkali metals and alkaline earth metals have large atomic and ionic radii. In their corresponding periods, alkali metals are the largest, followed by alkaline earth metals. Atomic radii increases further, as they move down a group.
3. DensityThe alkali metals have low density. This is because they have large ionic size and, therefore, their atomic nuclei are widely separated in their crystal lattices. Density gradually increases in moving down from lithium towards cesium.
4. Ionization EnergyThe first ionization energies of alkali metals are quite low as compared with the elements of the other groups belonging to the same period. This is because the s-electron in the valence shell being far away from the nucleus is weakly held by the nucleus. The distance of s-electron from the nucleus increases as we go down from lithium to cesium.As a result the ionization energy decreases in going from lithium to cesium. The second ionization energy, the energy to remove a second electron from the atom is extremely high, because the second electron has to be removed from a smaller positive ion and from a filled orbital too.Ionization energies: Li: 5.4 Na: 5.1 K: 4.3 Rb: 4.2 Cs: 3.9
5. Electropositive CharacterAlkali metals are the most electropositive elements in the periodic table. As alkali metals have low ionization energies, they have a great tendency to lose electrons forming uni-positive ions.
Atomic radii increases as we move down a group, the ionization energy decreases. And electropositivity increases
6. Oxidation StateThe alkali metal atoms show only +1 oxidation state, while alkaline earth metals show +2 oxidation state only. Because of their low ionization energies, they easily lose the outermost s electron to form the uni positive ions. Once they lose the first electron, in case of alkali metals, they achieve the noble gas configuration. The same is true with respect to alkaline earth metals, when they lose the 2 electrons present in the valence shell.
7. Flame colorationThe alkali metals and their salts, when introduced into the flame, give characteristic color to the flame.
Alkali metals :
lithium,
sodium,
potassium,
rubidium,
cesium,
and francium.
Group I A in periodic table.
They have valency electron 1 , they are not form free state in nature. they are ready to react with oxides and hydroxides gives strong hydride and oxide form . example NaOH,
And KOH.
They ready to give electron and form noble gas configuration. .
Atomic Radii: All Alkali metals have more atomic radii .
Ionic Radii: Is less in alkali metals because they have less number of shells
Density:
densities are lower than, those of other metals. Moving down Density increases.
Ionization energy: Alkali metals have low ionization energy
Melting and boiling points : low ,decreased to moving down
oxidation state : +1
Flame colour :Li - crimson red
Na - yellow
k - Violet
Rb - Red violet
Cr - Blue.
Alkali metals are with low ionization energies so they are more reactive ,they are ready to loss outer most one electron .these are have low electronegative ,so these are readily react with nonmetals ,specially halogens.
Oxides of alkali metals:many metals burn rapidly when heating in presence of oxygen and produces their oxides.
Group 1 metals react with oxygen to produces ionic oxides ,peroxides and super oxides.
oxides : 2 metal atoms with i oxygen atom , oxidation state is -2
4Li2 + O2 -à 2Li2 O
peroxide 2metal atom react with two molecules of oxygen, oxidation state is+1,peroxides are diamagnetic nature.
super peroxides 1 metal atoms react with 2 oxygen molecule,oxidation state is -1/2, super peroxides are paramagnetic nature.
Oxides ,peroxides and super peroxides are basic in nature, basicity increases from top to bottom ,Li<Na<K<Cr.
