Question

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In what way did electronegativity and electropositivity change down a group and along a period and why?I want better explanation
and
Definition : Electropositivity

Answer 1

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here's your answer!!☺☺

1) electro negativity:
ELECTRONEGATIVITY-TENDENCY OF AN ELEMENT TO ATTRACT SHARED PAIR OF ELECTRONS
electronegative elements pull the shared pair of electron towards itself. eg all halogens oxygen ..
fluorine is the most electronegative element in the periodic table. Most of the metals lying in the right of the periodic table are electro negative

2)electro positivity:
ELECTROPOSITIVITY-TENDENCY OF AN ELEMENT TO REPEL SHARED PAIR OF ELECTRONS
coming to the electropositive nature of alkali and alkaline earth metals .. they have very high tendacy to lose electrons inorder to attain noble gas configuration or octet in their outer most orbit.eg Na --> Na(+) + electron
Na config = 2,8,1
Na+ config = 2.8
thus na + has achieved octet and becomes stable.similar argument extends to other metals in 1a 2a and transition metals.
therefore they are electropositive.
TRANSITION ELEMENTS ARE METALS
THUS THEY ARE OBVIOUSLY ELECTROPOSITIVE.

Trend of electro negativity and electro positivity:
Electronegativity increases across a period while it decreases down a group.
Atomic radius increases down the group due to addition of new shell. Due to this the distance between nucleus and valence shell increases. And the nuclear attractions on the valence shell decrease hence electronegativity decreases.
The atomic radius decreases across a period. While moving from left to right in a period there is no addition of new shells but electrons are added to the same shell. Hence the nuclear attractions on outer most shell increases therefore electronegativity increases.
Here we have two elements with atomic numbers 35 and 75
The element 35 belongs to 4th period VIIA group and the element 75 belongs to 6th period VIIIB group
From the above information we can conclude that the element with atomic number 35 is more electronegative than the element with atomic number 75

hope it helps you!!☺☺