Structure and Properties of Matter Pt2

Question 1

Coordinate Covalent Bonds

Answer 1

• a covalent bond where both e- are from one atom

Question 2

Expanded Octet

Answer 2

• atoms period 3 or higher have vacant d orbitals to overfill the octet

Question 3

Resonance Structures

Answer 3

• Lewis structures that show the same relative position of atoms but different pairs of e- pairs
• blend between structures, not switching between

Question 4

Two Theories of Covalent Bonding

Answer 4

1. Valence bond theory
2. Hybridization

Question 5

Valence Bond Theory

Answer 5

• covalent bonds form when half-filled orbitals overlap
• must have opposite spin

Question 6

Hybridization

Answer 6

• methane has 4 identical bonds but no e- configuration makes 4 identical bonds
• 1 s orbital and 3 p orbitals hybridize to form 4 sp3 orbitals (takes on tetrahedral shape to minimize e-/e- repulsion
• hybrid orbitals all have the same amount of eng

Question 7

How to predict

Type of hybridization

Answer 7

• an e- group is any single/double/triple bond or lone pair
• # of e- groups tell you hybridization

Question 8

Sigma Bond

Answer 8

• formed by the end-to-end overlap of hybridized orbitals

Question 9

Pi Bond

Answer 9

• overlap of unhybridized p orbitals side-by-side above and below the nuclei

Question 10

VSEPR Theory

Answer 10

• e- groups around atoms are positioned as far from e/o as possible to minimize e- repulsion

Question 11

5 main VSEPR shapes w/o lone pairs

Answer 11

• AX2: linear (180)
• AX3: trigonal planar (120)
• AX4: tetrahedral (109.5)
• AX5: trigonal bipyramidal (120 + 90)
• AX6: octahedral (90)

Question 12

Repulsive forces that affect VSPER theory

Answer 12

LP-LP > LP-BP > BP-BP
lone pairs spread out more and take up more space due to e- repulsion

Question 13

VSEPR Notation

Answer 13

A = central atom
B/X = surrounding atoms
E = lone pairs

Question 14

VSEPR shapes with lone pairs

Answer 14

• AX2E: bent (<120)
• AX2E2: bent (<109.5)
• AX2E3: linear (180)
• AX3E: trigonal pyramidal (<109.5)

Question 15

Ionic Bond

Answer 15

• electrostatic attraction between ions
• ^EN > 1.7

Question 16

Lattic Energy

Answer 16

• eng released in the formation of ionic bonds
• indicates bond strength (must add a greater amt of eng to break the bond)
• ionic radius: smaller ion = stronger bond
• ionic charge: larger ionic charge = stronger bond

Question 17

Solubility of ionic compounds

Answer 17

• to be soluble: attractive forces between ions and water must be stronger than the attractive forces between the ions themselves
• larger ionic radius and smaller ionic charge

Question 18

Mechanical properties of ionic compounds

Answer 18

• hard and brittle (when stressed, charges align and repel)
• conductive when aq, free-flowing ions can carry a charge

Question 19

Molecular Solids and Allotropes

Answer 19

• similar structure to ionic compounds but are held together by IMF’s
• different form of an element that has different properties

Question 20

Diamond vs Graphite

Answer 20

Diamond (sp3):
- tetrahedral
- all covalent bonded
- very hard and brittle, high MP/BP
Graphite (sp2):
- unhybridized orbitals overlap to form planes
- delocalized pi electrons

Question 21

Network Covalent Solids

Answer 21

• continuous array with no natural beginning or end
• hard + brittle
• extremely high MP/BP
• insoluble
• poor conductors

Question 22

Electron-sea Model

Answer 22

• lattice structure of positive ions and delocalized e- sea
• metallic bond is electrostatic attraction between cation and delocalized e-

Question 23

Strength of Metallic Bonds

Answer 23

Stronger bonds means:
- more delocalized e-
- larger charge of cation
- smaller cation

Question 24

Properties of Metallic Compounds

Answer 24

• electrical and thermal conductivity due to e- sea
• malleability and ductility since cations can slide past e/o due to e- sea