The figure below shows the variation in the values of the first ionization energ
ID: 1069344 • Letter: T
Question
The figure below shows the variation in the values of the first ionization energies of the elements as a function of atomic number. Several repeating patterns and features are worth noting. Explain each of the following features:
a. High ionization energies for noble gases
b. Low ionization energies for Group 1 elements
c. The general increase in ionization energies across a period
d. The decrease in ionization energy on going from an element in Group 15 to its neighbor in Group 16
1. The figure below shows the variation in the values of the first ionization energies of the elements as a function of atomic number. Several repeating patterns and features are worth noting. in each of the following features: (10 points) a. High ionization energies for noble gases 1.15 b. Low ionization energies for Group l elements Fig. 1.15 The valaes of the imitalionenergies of elements plo Rs. c. The general increase in ionization energies across a period d. The decrease in ionization energy on going from an element in Group 15 to its neighbor in Group 16 e. The decrease in onization energy on going from an element in Group 2 to its neighbor in Group 13Explanation / Answer
b) Low ionisation energies for group 1 elements
The ionisation energy of an element is defined as the amount of energy requried to remove the outermost electron from an isolated gaseous neutral atom of that element resulting in the formation of a positive ion.
Group 1 elements are alkali metals(s-block) consists of the elements(lithium,sodium,potassium,rubidium,cesium and francium)
The alkali metals(group1 elements) have the lowest ionisation energies in their respective periods and are chemically more reactive.
Ionisation energy decreases down the group because the atomic size increases down the group and the nuclear force towards the outermost electron decreases.Therefore, the electrons can be removed by expanding less energy.Hence, their elctropositive character(the ability to lose an electron)increases.
d)Elements of Group 15(N,P,As,Sb,Bi) to 16(O,S,Br,I,At) belong to p-block and placed extreme right of the periodic table.
The ionisation energies of the elements decrease in going down a group.
down the group means the number of shells or atomic size increases and the shielding effect also increases.
a) The ionisation enmergies of elements vary across a period as well as on going down a group.
The variation of 1st ionisation energies of elements with atomic nos 1-60 is shown in the graph.the graph consists of several maxima and minima. . The maxima are shown at noble gases which possess stable configeration, and they have very high ionisation energies. the minima shows at alkali metals and have very low ionisation energies.
Elements of S-block and p-block expect noble gases are called representative elements. noble gases(group 18elements) have high ionisation energies in their periods and are chemically less reactive due to stable and greater symmetry of the electronic configeration(ns2np6) .
c) Ionisation energy across a period :
Across a period, ionisation energies are increse in moving from left to the right,because the nuclear change increses and the atomic size decreses.Therefore, the attractive forces between the nucleus and the valence electron increses to remove electron becomes more and more difficult. Hence, the ionisation energy increases with increase in atomic number in a period.
e)Group 2 elements(Be,Mg,Ca,Sr,Ba,Ra) are belongs to the s-block known as alkaline earth metals.
Group 13 elements(B,Al,Ga,In and Tl) belong to the neighbour group P-block.
The decrases ionisation energies of the elements means decrase on moving from top to the bottom in any group.
Down the group , the number of atomic size increses and the shielding effect also increases.Alothough nuclear charge increase in going down a group. so that the valence electrons get more and more loosely bound to the nucleus.