Molecular Structure

Question 1

Covalent bond

Answer 1

Electrostatic attraction between 2 nuclei and one or more shared pairs of electrons between them

Question 2

Covalent bonding

Answer 2

Sharing of 1 or more pairs of electrons

Question 3

Describe a sigma orbital

Answer 3

2 s/p orbitals overlap along x axis
Can rotate one end
Bond doesnt break

Question 4

Describe a pi orbital

Answer 4

2 p orbitals overlap along y/z axis
Cant rotate one end
Bond breaks

Question 5

Which the of orbital are the first shared pair of electrons found in

Answer 5

Sigma

Question 6

In which orbital are electrons more tightly bound

Answer 6

Sigma

Question 7

Compare the relative strengths and lengths of single double and triple covalent bonds

Answer 7

Single, low strength, long
Double, mid strength, mid length
Triple, high strength, short

Question 8

Name 6 unconventional dot and cross diagram formations

Answer 8

Less than full shell
Compound ions
Dative
Free radical electrons
More than 8 electrons in a shell (not shell 2)
Mixture of diagrams

Question 9

Buzz words for simple molecule shape questions

Answer 9

No. Bonding pairs
No. Lone pairs
No. Density points
Shape
Minimises repulsion
Angle, squeezed?
Weighted lone pairs

Question 10

4 sigma bonds, 0 lps

Answer 10

Tetrahedral
109.5*

Question 11

3 sigma bonds, 1 lps

Answer 11

Triangular based pyramid
Lp repels more than bps
107*
Ammonia

Question 12

2 sigma bonds, 2 lps

Answer 12

V shape
Los repel more than bps
104.5*
Water

Question 13

2 sigma bonds, 0 lps

Answer 13

Linear
180*

Question 14

3 sigma bonds, 0 lps

Answer 14

Trigonal plane
120*

Question 15

5 sigma bonds, 0 lps

Answer 15

Trigonal bypyramid
3: 120*
2: 90*

Question 16

6 sigma bonds, 0 lps

Answer 16

Octahedron (8 faces)
4: 90*
2: 90*

Question 17

What is the shape of a molecule determined by

Answer 17

Repulsion between electron pairs around central atom

Question 18

Define electronegativity

Answer 18

Ability of an atom to attract bonding e tronos in a covalent bond

Question 19

4 most electronegative elements

Answer 19

F
O
Cl
N

Question 20

Describe how electronegativity can lead to a polar BOND

Answer 20

Electron spends more time near one atom
Warps orbital shape
partial neg/pos charges

Question 21

Describe how electronegativity can lead to a polar MOLECULE

Answer 21

Polar bonds that don’t cancel each other out
Polarity = vectors

Question 22

Name 3 intermolecular forces

Answer 22

London forces
Permanent dipoles
Hydrogen bonds

Question 23

Describe london forces

Answer 23

Temporarily uneven electron distribution
Small dipole
Atom near another induces a dipole

Question 24

Name 3 factors that vary London force strength

Answer 24

Grip on outer electrons (more grip, less induction)
No. Electrons in molecule (more, more induction)
Molecule shape (more SA contact, more induction, branched < un branched

Question 25

Describe permanent dipole forces

Answer 25

Electronegative molecules
Oppositely charged ends orient together

Question 26

Describe hydrogen bonding

Answer 26

One molecules with a lp on N, O or F
One molecule with an H covalently bonded to an N, O or F

Question 27

Recite NH3 HF H2O hydrogen bonding table

Answer 27

NH3, 1 lp, 3 Hs, 1 HB

HF, 3 lp, 1 H, 1 HB

H2O, 2 lp, 2 H, 2 HB

Question 28

Name and describe 4 unique properties of water

Answer 28

High surface tension, strong H bond between molecules
High heat capacity, thermal energy stored in H bond vibrations
Liquid denser than solid/solid more volumous than liquid, long H bond length