electronegativity and polarity

Question 1

Define electronegativity

Answer 1

Electronegativity is the power of an atom to attract the pair of electrons in a covalent bond towards itself

Question 2

The electron distribution in a covalent bond between elements with different electronegativities will be?

Answer 2

Unsymmetrical

Question 3

What does this phenomenon arise from though?

Answer 3

the positive nucleus’s ability to attract the negatively charged electrons, in the outer shells, towards itself

Question 4

What is the most electronegative atom?

Answer 4

Flourine

Question 5

What causes flourine to be the most electronegative?

Answer 5

It is best at attracting electron density towards itself when covalently bonded to another atom

Question 6

What is the Pauling scale however?

Answer 6

The Pauling scale is used to assign a value of electronegativity for each atoms

Question 7

Do electronegativity increase as you go down a group or period?

Answer 7

Period

Question 8

Does electronegativity decrease if you go down a group or period?

Answer 8

Group

Question 9

What factors affect electronegativity across a group or a period rather?

Answer 9

Proton number, atomic radius and shielding

Question 10

How does nuclear charge affect electronegativity?

Answer 10

Attraction exists between the positively charged protons in the nucleus and negatively charged electrons found in the energy levels of an atom
An increase in the number of protons leads to an increase in nuclear attraction for the electrons in the outer shells
Therefore, an increased nuclear charge results in an increased electronegativity

Question 11

How does atomic radius affect electronegativity?

Answer 11

The atomic radius is the distance between the nucleus and electrons in the outermost shell
Electrons closer to the nucleus are more strongly attracted towards its positive nucleus
Those electrons further away from the nucleus are less strongly attracted towards the nucleus
Therefore, an increased atomic radius results in a decreased electronegativity

Question 12

How does shielding affect electronegativity?

Answer 12

Filled energy levels can shield (mask) the effect of the nuclear charge causing the outer electrons to be less attracted to the nucleus
Therefore, the addition of extra shells and subshells in an atom will cause the outer electrons to experience less of the attractive force of the nucleus
Sodium (period 3, group 1) has higher electronegativity than caesium (period 6, group 1) as it has fewer shells and therefore the outer electrons experience less shielding than in caesium
Thus, an increased number of inner shells and subshells will result in a decreased electronegativity

Question 13

Why is there a decrease in electronegativity down a group?

Answer 13

There is a decrease in electronegativity going down the group
The nuclear charge increases as more protons are being added to the nucleus
However, each element has an extra filled electron shell, which increases shielding
The addition of the extra shells increases the distance between the nucleus and the outer electrons resulting in larger atomic radii
Overall, there is decrease in attraction between the nucleus and outer bonding electrons

Question 14

Why is there increase in electronegativity across a period?

Answer 14

Electronegativity increases across a period
The nuclear charge increases with the addition of protons to the nucleus
Shielding remains relatively constant across the period as no new shells are being added to the atoms
The nucleus has an increasingly strong attraction for the bonding pair of electrons of atoms across the period of the periodic table
This results in smaller atomic radii

Question 15

Explain polarity

Answer 15

If When two atoms in a covalent bond have the same electronegativity the covalent bond is nonpolar so