Explain the trends in modern periotic table more than 100 to 150 word ?
Answers
Answer:
(a) Valency- Combing capacity of atoms. The number of valence electrons in metals and 8 minus the number of valence electrons in non-metals.
In a group- As we go down a group in the Periodic Table the number of valence electrons stay the same. While moving down a group the valency stays the same.
In a period- As we move from left to right in a period the number of valence electrons increase. While moving left to right in a period the valency increases to 4 then decreases to 0.
(b) Atomic Size- Measured by the atomic radius of the atom. Which is the distance between the center of the nucleus to the outermost shell.
In a group- As we go down a group the atomic radius keeps increasing due to the increase in number of shells. While moving down a group the atomic size keeps increasing.
In a period- As we move from left to right in a period the atomic radius decreases at first then increases for the noble gas. While moving left to right in a period the atomic size first decreases then increases for the noble element.
(c) Metallic Character or Electropositivity- The level of reactivity of a metal and the measure of the ability of elements (mainly metals) to donate electrons to form positive ions.
In a group- As we go down a group the number of shells increases and thus losing electrons becomes easier for the atom. While moving down a group the metallic character increases.
In a period- As we move from left to right in a period the tendency to gain electrons reduces. While moving left to right in a period the metallic character reduces.
(c) Non-metallic Character or Electronegativity- The level of reactivity of a non-metal and the tendency of an atom to attract a bonding pair of electrons.
In a group- As we go down a group the number of shells increases and thus gaining electrons becomes harder for the atom. While moving down a group the non-metallic character decreases.
In a period- As we move from left to right in a period the tendency to gain electrons reduces.While moving left to right in a period the non-metallic character increases.
(d) Chemical Reactivity- the quality of being reactive.
In a group-
In a metals group- As we go down a group the chemical reactivity of metals increases as it more easy to lose electrons due to their increase in shells. While moving down a group the chemical reactivity of metals increases.
In a non-metals group- As we go down a group the the chemical reactivity of non-metals decreases as it becomes harder to gain electrons with the increase in shells. While moving down a group the chemical reactivity of non-metals decreases.
In a period- As we move from left to right in a period the chemical reactivity of metals decreases then the chemical reactivity of non-metals increases and is nil for noble elements. While moving left to right in a period the chemical reactivity first decreases then increases.
(e) Acidic and Basic nature- to determine whether their oxides are acidic or basic in nature.
In a group-
In a metals group- As we go down a group the pH value of acidic oxides increases. While moving down a group the acidic nature of metals increases.
In a non-metals group- As we go down a group the pH value of basic oxides decreases. While moving down a group the basic nature of non-metals decreases.
In a period- As we move from left to right in a period first the acidic nature decreases and the basic nature increases while it’s nil for noble elements. While moving left to right in a period the acidic nature decreases and basic nature increases.