explain the trends:-
1.atomic size- down the group and across the period
2. metallic character-down the group and across the period
3. non metallic character- down the group and across the period
plz ans this que Tomorrow is my periodic test
Answers
Atomic size:
Atomic size is the distance between the centre of the nucleus to the outermost shell.
Atomic size
- increases down the group
- decreases across a period.
Metallic character:
Metallic character is the character of elements to donate electrons and form positive ions.
Metallic character
- increases down the group and
- decreases across a period.
Non Metallic character:
Non metallic character is the character of elements to accept electrons and form negative ions.
Non metallic character
- decreases down the group and
- increases across a period.
Know more:
★ Modern Periodic table is given by Henry Moseley.
★ Modern Periodic table is based on the increasing order of atomic number.
★ It consists of 18 vertical rows called groups and 7 horizontal columns called periods.
1) Atomic size increases down the group as with each element the number of electron shells increases by one. So, atomic size increases down the group.
Across a period, the atomic size decreases, because the number of shells remains the same, but the atomic number keeps increasing, so the number of protons in the nucleus keeps increasing, this increases the positive nuclear charge of the nucleus, the increasing attractive effect of the positive nuclear charge on the negatively charged electrons causes decreasing atomic size from left to right across a period.
2) Metallic character increases as we go down the group, the number of electron shells keeps increasing by one, this means that atomic size also increases, the increasing atomic size means that the influence of the positive nuclear charge on the valence electrons reduces meaning that the amount of energy required to remove electrons from the valence shell or the ionization potential decreases, this makes it more and more easier for electrons to be lost from the outermost shell as we go down a group and hence the metallic character increases down the group.
Across the period, the metallic character decreases as the atomic size keeps decreasing, this makes it more difficult for valence electrons to be lost due to increasing attractive force on them because of the increasing positive nuclear charge.
3) Nonmetallic character decreases down the group as the number of electron shells keeps increasing, this increases the atomic size and decreases the influence of positive nuclear charge on the valence electrons, thus, due to less attractive force of positive nuclear charge due to larger atomic size, the atom finds it more difficult to gain electrons, thus the non metallic character decreases.
Nonmetallic character increases from left to right across a period, as the number of electron shells remains the same and positive nuclear charge increases due to increase in atomic number, due to increasing influence of positive nuclear charge, the atomic size also reduces, thus the element finds it easier to gain electrons and nonmetallic character increases.