Chemical Bonding Flashcards
Define electronegativity
Electronegativity is a measure of the tendency of an atom to attract electrons towards itself
Factors affecting electronegativity (3)
1) Nuclear charge
2) Shielding
3) Atomic radius
Explain the trends of electronegativity down a group and across a period
Electronegativity decreases down the group as atomic radius increases and shielding effect increases.
Electronegativity increases across a period as nuclear charge increases and shielding effect is almost the same. Atomic radius decreases
Using Pauling’s electronegativity values, what will it be when it is non-polar covalent?
Less than 0.4
Using Pauling’s electronegativity values, what will it be when it is polar covalent?
Between 0.4 and 1.7
Using Pauling’s electronegativity values, what will it be when it is ionic?
Greater than 1.7
Define ionic bonding
Ionic bonding consists of strong electrostatic forces of attraction between cations and anions
Define metallic bonding
Strong electrostatic forces between cations and delocalised electrons
Define covalent bonding
Strong electrostatic forces of attraction between the nucleus of an atom towards the electrons of another atom
What should we keep in mind when covalent bonding occurs for elements of period 3 and above?
Third row elements and above can use their empty d orbitals for bonding. Hence they can have more than 8 electrons in their outermost shell
When does coordinate (dative) bonding occur?
Dative covalent bond occurs when both electrons in the covalent bond are provided by the same atom
What causes sigma bond?
The head-on overlapping of orbitals
What causes the pi bond?
The sideways overlapping of p orbitals
Why can we not rotate a molecule about a pi bond?
Rotation is not possible as the overlap of orbitals is above and below the plane of the molecule
Define hybridisation
Hybridisation is the mixing of atomic orbitals