In the previous section, we saw how to determine the group number of an element from it's S.E.C. We also saw which all groups fall under each block. In this section we will see the properties of s-block and p-block elements.
■ Position: The s-block consists of the groups I and II of the periodic table
■ Common names:
• Group I elements have the common name Alkali metals
• Group II elements have the common name Alkaline earth metals (Details here)
■ Acceptance or Donation of electrons during chemical reactions:
Consider the elements Li, Na and K of Group I. Let us write their S.E.C:
1. Li - 1s22s1
• The outer most main shell is 2.
• This main shell has one electron, which is in 2s subshell
• During chemical reactions, this one electron is donated. This is because, donating one electron is easier than accepting 7 electrons to attain octet
2. Na - 1s22s22p63s1
• The outer most main shell is 3.
• This main shell has one electron, which is in 3s subshell
• During chemical reactions, this one electron is donated. This is because, donating one electron is easier than accepting 7 electrons to attain octet
3. K - 1s22s22p63s23p64s1
• The outer most main shell is 4.
• This main shell has one electron, which is in 4s subshell
• During chemical reactions, this one electron is donated. This is because, donating one electron is easier than accepting 7 electrons to attain octet
Consider the elements Be, Mg and Ca of Group II. Let us write their S.E.C:
1. Be - 1s22s2
• The outer most main shell is 2.
• This main shell has two electrons, which is in 2s subshell
• During chemical reactions, these two electrons are donated. This is because, donating two electrons is easier than accepting 6 electrons to attain octet
2. Mg - 1s22s22p63s2
• The outer most main shell is 3.
• This main shell has two electrons, which is in 3s subshell
• During chemical reactions, these two electrons are donated. This is because, donating two electrons is easier than accepting 6 electrons to attain octet
3. Ca - 1s22s22p63s23p64s2
• The outer most main shell is 4.
• This main shell has two electrons, which is in 4s subshell
• During chemical reactions, these two electrons are donated. This is because, donating two electrons is easier than accepting 6 electrons to attain octet
■ Oxidation state
• All the elements in group I always donate 1 electron. So they always show an oxidation state of +1
• All the elements in group II always donate 2 electrons. So they always show an oxidation state of +2
• We have seen that some elements show fixed oxidation states which ever be the reaction. While some others show variable oxidation states. (We have seen details about oxidation number or oxidation state here)
♦ Groups I and II elements always show definite fixed oxidation states.
■ Atomic radius
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the atomic radius decreases as we move from left to right in a period.
• The s-block elements are at the left most end of the various periods. So we can say that, the s-block elements have high atomic radius
• Also, when we move from top to bottom in any group in the s-block, the atomic radius increases
■ Ionization energy
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the ionization energy increases as we move from left to right in a period.
• The s-block elements are at the left most end of the various periods. So we can say that, the s-block elements have low ionization energy
• That means lower energies are sufficient to remove electrons from the s-block elements
• Also these elements form mostly ionic compounds
■ Electronegativity
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the electronegativity increases as we move from left to right in a period.
• The s-block elements are at the left most end of the various periods. So we can say that, the s-block elements have low electronegativity
■ Metallic nature
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the metallic nature decreases as we move from left to right in a period.
• The s-block elements are at the left most end of the various periods. So we can say that, the s-block elements have high metallic nature
■ Reactivity
• The Group I elements will be the first element in respective periods.
• These first elements have the greatest reactivity in the respective periods
• Also, the reactivity increases as we move from top to bottom in the groups
■ Oxides and hydroxides
• Magnesium oxide (MgO) is an example of an oxide of an s-block element. It is formed when magnesium ribbon burns in air.
♦ Other examples of oxides from this s-block are: Calcium oxide (CaO) and Barium oxide (BaO)
• Sodium hydroxide (NaOH) and Potassium hydroxide (KOH) are examples of hydroxides formed from this block. They are alkaline in nature.
• Metallic oxides give alkalies and non-metallic oxides give acids. We have seen the details in an earlier chapter here.
♦ Above we have seen that s-block elements are metallic in nature. So we can say that the oxides and hydroxides formed from this block are alkaline in nature.
■ Position: The p-block consists of the groups 13 to 18 of the periodic table
■ S.E.C:
• We know that, the last electron of each element in the p-block will be filled in the p subshell. That means, there will always be a p subshell in the last main shell of any p-block element
• Now, p subshell will be filled only after completing the s subshell. So, the last main shell will contain a s subshell also.
• Thus, The general form of the last main shell configuration is: ns2np(1 to 6).
• Where n is the last main shell. The superscript for s will always be 2
• The superscript for p varies from 1 to 6. This is shown below:
The superscript for p for all elements in group 13 will be 1 (Add 12 to 1, and we get the group no.13)
The superscript for p for all elements in group 14 will be 2 (Add 12 to 2, and we get the group no.14)
The superscript for p for all elements in group 15 will be 3 (Add 12 to 3, and we get the group no.15)
The superscript for p for all elements in group 16 will be 4 (Add 12 to 4, and we get the group no.16)
The superscript for p for all elements in group 17 will be 5 (Add 12 to 5, and we get the group no.17)
The superscript for p for all elements in group 18 will be 6 (Add 12 to 6, and we get the group no.18)
An example:
• 34Se - 1s22s22p63s23p63d104s24p4 OR [Ar]3d104s24p4.
♦ Add 12 to the subscript 4 of the 4p subshell. We get 16, which is indeed the group number of Selenium
■ Common names:
• Group 13 elements have the common name Boron family
• Group 14 elements have the common name Carbon family
• Group 15 elements have the common name Nitrogen family
• Group 16 elements have the common name Oxygen family
• Group 17 elements have the common name Halogens
• Group 18 elements have the common name Noble gases
■ Oxidation state
• Some of the elements in the p-block shows variable oxidation states. But in general, we can write the values as follows:
• +3 oxidation state for group 13 elements
♦ donating 3 electrons in the outermost main shell
• +4 oxidation state for group 14 elements
♦ sharing 4 pairs of electrons in the outermost main shell. But all the 4 electrons will move away because of low electronegativity
• -3 oxidation state for group 15 elements
♦ there are 5 electrons in the outermost main shell. Will accept 3 electrons to attain octet
• -2 oxidation state for group 16 elements
♦ there are 6 electrons in the outermost main shell. Will accept 2 electrons to attain octet
• -1 oxidation state for group 17 elements
♦ there are 7 electrons in the outermost main shell. Will accept 1 electron to attain octet
• 0 oxidation state for group 18 elements
♦ Already have an octet configuration
• The above values should be used only as general guide lines. Accurate values should be carefully calculated for each compound.
■ Atomic radius
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the atomic radius decreases as we move from left to right in a period.
• So, as we move from left to right in any period in the p-block, the atomic radius decreases
• Also, when we move from top to bottom in any group in the p-block, the atomic radius increases
■ Ionization energy
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the ionization energy increases as we move from left to right in a period.
• So, as we move from left to right in any period in the p-block, the ionization energy increases
• Also, when we move from top to bottom in any group in the p-block, the ionisation energy decreases
■ Electronegativity
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the electronegativity increases as we move from left to right in a period.
• So, as we move from left to right in any period in the p-block, the electronegativity increases
• Also, when we move from top to bottom in any group in the p-block, the electronegativity decreases
■ Metallic nature
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the metallic nature decreases as we move from left to right in a period.
• So, as we move from left to right in any period in the p-block, the metallic nature decreases
• Also, when we move from top to bottom in any group in the p-block, the metallic nature increases
• Among the p-block elements, both metals and non-metals are present
■ Reactivity
• Consider the Group 17 elements.
• They have the smallest atomic size among the p-block elements
• They have the highest electronegativity among the p-block elements
• They need only one more electron to attain octet
• So they have the highest reactivity among the p-block elements
• These first elements have the greatest reactivity in the respective periods
• Also, the reactivity increases as we move from top to bottom in the groups
■ The Group 18 elements needs special mention
• They have eight electrons in the outermost shell
• Their S.E.C ends with ns2np6
• They already have octet. So they does not show any reactivity.
• All the elements in this group are gases
• They are mono atomic because they do not need to combine with other atoms for stability
In the next section, we will see the properties of d-block and f-block elements.
Properties of s-block elements
■ Position: The s-block consists of the groups I and II of the periodic table
■ Common names:
• Group I elements have the common name Alkali metals
• Group II elements have the common name Alkaline earth metals (Details here)
■ Acceptance or Donation of electrons during chemical reactions:
Consider the elements Li, Na and K of Group I. Let us write their S.E.C:
1. Li - 1s22s1
• The outer most main shell is 2.
• This main shell has one electron, which is in 2s subshell
• During chemical reactions, this one electron is donated. This is because, donating one electron is easier than accepting 7 electrons to attain octet
2. Na - 1s22s22p63s1
• The outer most main shell is 3.
• This main shell has one electron, which is in 3s subshell
• During chemical reactions, this one electron is donated. This is because, donating one electron is easier than accepting 7 electrons to attain octet
3. K - 1s22s22p63s23p64s1
• The outer most main shell is 4.
• This main shell has one electron, which is in 4s subshell
• During chemical reactions, this one electron is donated. This is because, donating one electron is easier than accepting 7 electrons to attain octet
Consider the elements Be, Mg and Ca of Group II. Let us write their S.E.C:
1. Be - 1s22s2
• The outer most main shell is 2.
• This main shell has two electrons, which is in 2s subshell
• During chemical reactions, these two electrons are donated. This is because, donating two electrons is easier than accepting 6 electrons to attain octet
2. Mg - 1s22s22p63s2
• The outer most main shell is 3.
• This main shell has two electrons, which is in 3s subshell
• During chemical reactions, these two electrons are donated. This is because, donating two electrons is easier than accepting 6 electrons to attain octet
3. Ca - 1s22s22p63s23p64s2
• The outer most main shell is 4.
• This main shell has two electrons, which is in 4s subshell
• During chemical reactions, these two electrons are donated. This is because, donating two electrons is easier than accepting 6 electrons to attain octet
■ Oxidation state
• All the elements in group I always donate 1 electron. So they always show an oxidation state of +1
• All the elements in group II always donate 2 electrons. So they always show an oxidation state of +2
• We have seen that some elements show fixed oxidation states which ever be the reaction. While some others show variable oxidation states. (We have seen details about oxidation number or oxidation state here)
♦ Groups I and II elements always show definite fixed oxidation states.
■ Atomic radius
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the atomic radius decreases as we move from left to right in a period.
• The s-block elements are at the left most end of the various periods. So we can say that, the s-block elements have high atomic radius
• Also, when we move from top to bottom in any group in the s-block, the atomic radius increases
■ Ionization energy
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the ionization energy increases as we move from left to right in a period.
• The s-block elements are at the left most end of the various periods. So we can say that, the s-block elements have low ionization energy
• That means lower energies are sufficient to remove electrons from the s-block elements
• Also these elements form mostly ionic compounds
■ Electronegativity
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the electronegativity increases as we move from left to right in a period.
• The s-block elements are at the left most end of the various periods. So we can say that, the s-block elements have low electronegativity
■ Metallic nature
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the metallic nature decreases as we move from left to right in a period.
• The s-block elements are at the left most end of the various periods. So we can say that, the s-block elements have high metallic nature
■ Reactivity
• The Group I elements will be the first element in respective periods.
• These first elements have the greatest reactivity in the respective periods
• Also, the reactivity increases as we move from top to bottom in the groups
■ Oxides and hydroxides
• Magnesium oxide (MgO) is an example of an oxide of an s-block element. It is formed when magnesium ribbon burns in air.
♦ Other examples of oxides from this s-block are: Calcium oxide (CaO) and Barium oxide (BaO)
• Sodium hydroxide (NaOH) and Potassium hydroxide (KOH) are examples of hydroxides formed from this block. They are alkaline in nature.
• Metallic oxides give alkalies and non-metallic oxides give acids. We have seen the details in an earlier chapter here.
♦ Above we have seen that s-block elements are metallic in nature. So we can say that the oxides and hydroxides formed from this block are alkaline in nature.
Properties of p-block elements
■ Position: The p-block consists of the groups 13 to 18 of the periodic table
■ S.E.C:
• We know that, the last electron of each element in the p-block will be filled in the p subshell. That means, there will always be a p subshell in the last main shell of any p-block element
• Now, p subshell will be filled only after completing the s subshell. So, the last main shell will contain a s subshell also.
• Thus, The general form of the last main shell configuration is: ns2np(1 to 6).
• Where n is the last main shell. The superscript for s will always be 2
• The superscript for p varies from 1 to 6. This is shown below:
The superscript for p for all elements in group 13 will be 1 (Add 12 to 1, and we get the group no.13)
The superscript for p for all elements in group 14 will be 2 (Add 12 to 2, and we get the group no.14)
The superscript for p for all elements in group 15 will be 3 (Add 12 to 3, and we get the group no.15)
The superscript for p for all elements in group 16 will be 4 (Add 12 to 4, and we get the group no.16)
The superscript for p for all elements in group 17 will be 5 (Add 12 to 5, and we get the group no.17)
The superscript for p for all elements in group 18 will be 6 (Add 12 to 6, and we get the group no.18)
An example:
• 34Se - 1s22s22p63s23p63d104s24p4 OR [Ar]3d104s24p4.
♦ Add 12 to the subscript 4 of the 4p subshell. We get 16, which is indeed the group number of Selenium
■ Common names:
• Group 13 elements have the common name Boron family
• Group 14 elements have the common name Carbon family
• Group 15 elements have the common name Nitrogen family
• Group 16 elements have the common name Oxygen family
• Group 17 elements have the common name Halogens
• Group 18 elements have the common name Noble gases
■ Oxidation state
• Some of the elements in the p-block shows variable oxidation states. But in general, we can write the values as follows:
• +3 oxidation state for group 13 elements
♦ donating 3 electrons in the outermost main shell
• +4 oxidation state for group 14 elements
♦ sharing 4 pairs of electrons in the outermost main shell. But all the 4 electrons will move away because of low electronegativity
• -3 oxidation state for group 15 elements
♦ there are 5 electrons in the outermost main shell. Will accept 3 electrons to attain octet
• -2 oxidation state for group 16 elements
♦ there are 6 electrons in the outermost main shell. Will accept 2 electrons to attain octet
• -1 oxidation state for group 17 elements
♦ there are 7 electrons in the outermost main shell. Will accept 1 electron to attain octet
• 0 oxidation state for group 18 elements
♦ Already have an octet configuration
• The above values should be used only as general guide lines. Accurate values should be carefully calculated for each compound.
■ Atomic radius
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the atomic radius decreases as we move from left to right in a period.
• So, as we move from left to right in any period in the p-block, the atomic radius decreases
• Also, when we move from top to bottom in any group in the p-block, the atomic radius increases
■ Ionization energy
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the ionization energy increases as we move from left to right in a period.
• So, as we move from left to right in any period in the p-block, the ionization energy increases
• Also, when we move from top to bottom in any group in the p-block, the ionisation energy decreases
■ Electronegativity
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the electronegativity increases as we move from left to right in a period.
• So, as we move from left to right in any period in the p-block, the electronegativity increases
• Also, when we move from top to bottom in any group in the p-block, the electronegativity decreases
■ Metallic nature
• We have learned about periodic trends in an earlier chapter. Details here. We have seen that the metallic nature decreases as we move from left to right in a period.
• So, as we move from left to right in any period in the p-block, the metallic nature decreases
• Also, when we move from top to bottom in any group in the p-block, the metallic nature increases
• Among the p-block elements, both metals and non-metals are present
■ Reactivity
• Consider the Group 17 elements.
• They have the smallest atomic size among the p-block elements
• They have the highest electronegativity among the p-block elements
• They need only one more electron to attain octet
• So they have the highest reactivity among the p-block elements
• These first elements have the greatest reactivity in the respective periods
• Also, the reactivity increases as we move from top to bottom in the groups
■ The Group 18 elements needs special mention
• They have eight electrons in the outermost shell
• Their S.E.C ends with ns2np6
• They already have octet. So they does not show any reactivity.
• All the elements in this group are gases
• They are mono atomic because they do not need to combine with other atoms for stability
In the next section, we will see the properties of d-block and f-block elements.
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