Chemical Bonding

Question 1

Intramolecular forces

Answer 1

Hold atoms together. Ionic and covalent bonds

Question 2

Intermolecular forces

Answer 2

Weaker forces between molecules

Question 3

Octet rule

Answer 3

An atom tends to bond with other atoms until it has eight electrons in its outermost shell

Question 4

Ionic bonds

Answer 4

One or more electrons from an atom with a smaller IE are transferred to an atom with greater EA. Ions held together by electrostatic forces.
EN difference >1.7
Form crystal lattices of arrays of + and - ions.
High melting and boiling points. Conductive

Question 5

Covalent bonds

Answer 5

Electron pair shared between two atoms.

Low melting and boiling points. Not conductive.

Question 6

Bond order

Answer 6

The number of shared electron pairs between 2 atoms

Question 7

Bond length

Answer 7

The average distance between the two nuclei of the atoms involved in a bond. Decreases with increasing number of shared electron pairs

Question 8

Bond energy

Answer 8

The energy required to separate two bonded atoms. Increases with increasing number of shared electron pairs

Question 9

Bonding electrons

Answer 9

The shared valence electrons of a covalent bond

Question 10

Lone Pairs

Answer 10

Unshared electrons pairs

Question 11

Lewis structure

Answer 11

A notation to represent the bonding and nonbonding electrons in a molecule

Question 12

Formal charge

Answer 12

The difference between the number of electrons in an atom in a Lewis structure and the number of valence electrons of the free atom.
fc = v - 1/2Nbonding - Nnonbonding

Question 13

Resonance structures

Answer 13

A hybrid of more than one Lewis structure for a single molecule unable to be described fully with only one Lewis structure

Question 14

Polar covalent bond

Answer 14

Between atoms with small EN differences, 0.4 - 1.7. Creates partial charges

Question 15

Dipole moment

Answer 15

The product of the charge magnitude and distance between two partial charges: u = qr
Debye units (C m)

Question 16

Nonpolar covalent bond

Answer 16

Between atoms that have the same EN

Question 17

Coordinate covalent bond

Answer 17

Shared electron pair comes from the lone pair of one atom in the molecule

Question 18

Lewis acid

Answer 18

Accepts an electron pair

Question 19

Lewis base

Answer 19

Donates an electron pair

Question 20

Valence shell electron-pair repulsion (VSEPR)

Answer 20

Uses Lewis structures to predict geometry of covalently bonded molecules. Atoms arrange to minimize replusion

Question 21

Molecular orbital

Answer 21

The probability of finding the bonding electrons

Obtained by adding the wave functions of atomic orbitals

Question 22

Bonding orbital

Answer 22

When the signs of two atomic orbitals are the same

Question 23

Antibonding orbital

Answer 23

When the signs of two atomic orbitals are different

Question 24

Sigma bond

Answer 24

When two orbitals of different atoms overlap head-to-head

Question 25

Pi bond

Answer 25

When two p orbitals of different atoms interact

Question 26

van der Waals forces

Answer 26

The intermolecular forces due to interactions of ions or hydrogen bonding

Question 27

Dipole-dipole interactions

Answer 27

Polar molecules orient themselves such that the positive region is close to the negative region of another to be energetically favourable

Question 28

Hydrogen bonding

Answer 28

Particularly strong dipole-dipole interactions when a H is covalently bound to F, O or N. The positively charged H interacts with the partially negative charged electronegative atom

Question 29

London dispersion forces

Answer 29

Unequal sharing of electrons cause rapid polarization and counterpolarization of the electron cloud and formation of short-lived dipoles to interact with the electron clouds of neighbouring molecules