6.2- Electronegativity And Polarity

Question 1

Define electronegativity

Answer 1

The ability of an atom to attract the pair of electrons in a covalent bond

Question 2

What does it mean when the bond is non polar?

Answer 2

The electrons in the bond are evenly distributed

Question 3

What is the most electronegative element?

Answer 3

Fluorine

Question 4

How is a polar bond formed?

Answer 4

Bonding atoms have different electronegativites

Question 5

How does electronegativity change across the periodic table?

Answer 5

• lowest at the bottom left ( metals ) of the periodic table as there is the lowest effective nuclear charge and highest shielding
• highest in the top right ( non metals ) as there is the highest effective nucleur charge as well as low shielding

Question 6

How does electronegativity affect bonding?

Answer 6

• in metals and non-metals their difference in electronegativity is large that it thus causes electrons to be transferred from the non metal to the metal

• in only non metals = if the 2 atoms are of the same element = same electronegativity = they’re nonpolar, have no dipole and the electrons are shared equally within the covalent bond

• if two elements in the covalent bond are different = differ in electronegativity = more electronegative element will attract the bonding pair of electrons more and so the pair will be shared unequally within me covalent bond = forms a dipole across the molecule = more electronegative is delta negative and less electronegative is delta positive = molecule is polar

Question 7

What are dipole forces?

Answer 7

The attractive forces between 2 neighbouring molecules with a permanent dipole

Question 8

What molecules have London dispersion forces?

Answer 8

• all molecules in the electron pair are constantly moving around so at any given time they can have an instantaneous dipole = repels the electron pair away from the other atom or molecule inducing a dipole = the attraction between the two atoms forms the London dispersion force

Question 9

What does the strength of the London dispersion force depend upon?

Answer 9

Strength increases with the size of the molecule as its Mr increases

Question 10

What type of molecules have permanent dipole forces?

Answer 10

• polar molecules

Question 11

Describe the structure of iodine

Answer 11

• diatomic , covalently bonded molecule
• between the molecule exists weak London dispersion intermolecular forces which give it its molecular crystal lattice structure
• shiny grey solid at room temperature and has a very low melting point causing it to sublime to purple vapour as the weak London forces between the 12 molecules require little energy to overcome
• slightly soluble in water
• largerly insoluble as it is non polar but in a solution of KL it can be dissolved as there are I- ions bonded to potassium ions