bonding - 3.4 electronegativity - bond polarity in covalent bonds

Question 1

define electronegativity

Answer 1

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

Question 2

if fluorine or hydrogen more electronegative

Answer 2

fluorine

Question 3

what does electronegativity depend on

Answer 3

-nuclear charge
the bigger nuclear charge, the more protons, the stronger attraction between nucleus and outer electrons, so the greater the electronegativity

-atomic radius
the smaller the atom, the closer the outer shared main level electrons are to the nucleus, the greater the electronegativity

-shielding
the more shielding (inner energy levels), the weaker the electronegativity

Question 4

explain the trends in electronegativity down a group

Answer 4

electronegativity decreases

-atomic radius increases, larger distance between outer level electrons and nucleus (weaker attraction between outer level electrons and nucleus)

-more shielding (more energy levels) = weaker attraction

Question 5

explain the trends in electronegativity across a period

Answer 5

electronegativity increases

-nuclear charge increases
more protons, stronger attraction between positive nucleus and outer level negative electrons

-shielding stays the same

-atomic radius decreases
distance between nucleus and outer electrons is smaller, so stronger attraction between positive nucleus and outer level negative electrons

Question 6

describe the covalent bond between 2 atoms that are the same in terms of electronegativity and polarity

Answer 6

when both atoms are the same, the electrons in the bond must be shared equally between the atoms so they have the same electronegativity and the bond is completely non-polar

Question 7

describe the covalent bond between 2 atoms that are different in terms of electronegativity and polarity

Answer 7

in a covalent bond between 2 atoms that are different, the electronegativity is different and the electrons in the bond will not be shared equally. the bond is polar. the bigger the difference of electronegativity between the 2 atoms, the more polar is the covalent bond.