Lecture 7 - Chemical Bonding

Question 1

what is coulombs law?

Answer 1

the strength of an electrostatic interaction is proportional to the size of the charge and inversely proportional to the distance squared

Question 2

what is electronegativity?

Answer 2

the ability of an atom to attract toward itself the electrons in a chemical bond

Question 3

what does electronegativity depend on?

Answer 3

• the number of protons in the nucleus
• the distance from the nucleus/size of the atom
• the amount of screening by inner electrons shells between the valance shell and the nucleus

Question 4

Describe ionic bonding

Answer 4

they are formed when one or more electrons are fully transferred between atoms
-the positive and negative ions attract each other via electrostatic attraction to give an ionic bond

Question 5

Give 5 properties of an ionic bond

Answer 5

• formed due to electrostatic attraction
• non directional
• ionic compounds can dissolve and disassociate in polar solvents
• bonds break when the substance is melted
• ionic compounds are not charged overall

Question 6

what is lattice enthalpy?

Answer 6

the enthalpy of formation of forming one mole of the ionic solid from its gaseous ions

Question 7

what are the factors favouring ionic bonding?

Answer 7

• easy cation formation
• easy anion formation
• large electronegativity
• high lattice energy of ionic compound

Question 8

what is polarisation?

Answer 8

distortion of the electron cloud of an atom

Question 9

what is Fajan’s rule?

Answer 9

an ionic compound is likely to have some covalent character if the

• cation is small and/or has high charge = highly polarising
• the anion his large and /or has a high charge = highly polarisable

Question 10

what is CH3CO2- ?

Answer 10

acetate

Question 11

what is C2O4 2- ?

Answer 11

oxalate