CHM103_Chapter_4.3

Chapter 4: Forces Between Particles

• Focuses on interactions between particles and how these interactions define properties of substances.

Page 1

• Title: Forces Between Particles

• Source: Thomson Higher Education, 2007

Page 2

Practice with Lewis Dot Structures

• NH3 (Ammonia)

• CH4 (Methane)

• H2S (Hydrogen Sulfide)

• HCN (Hydrogen Cyanide)

• C2H4 (Ethylene)

• SiF4 (Silicon Tetrafluoride)

• SO4^2- (Sulfate Ion)

• NO3^- (Nitrate Ion)

• PCl3 (Phosphorus Trichloride)

Page 3

CO2 Lewis Dot Structure Analysis

• Options to choose regarding the valence electrons and bonds:

  • 12 valence e-, no double bonds

  • 14 valence e-, 1 double bond

  • 16 valence e-, 2 double bonds

  • 18 valence e-, no double bonds

Page 4

Confirmation of CO2 Lewis Dot Structure Options

• Repeat of CO2 structure options presented previously.

  • Correct option identified.

Page 5

Naming Covalent Molecules

• Use of Greek Prefixes for naming:

  • Mono – 1

  • Di – 2

  • Tri – 3

  • Tetra – 4

  • Penta – 5

  • Hexa – 6

  • Hepta – 7

  • Octa – 8

  • Nona – 9

  • Deca – 10

• Covalent compounds share electrons and do not contain metal atoms.

• Examples include complex biological molecules (e.g., DNA, proteins).

Page 6

Examples of Binary Covalent Compounds

• Common examples include:

  • Carbon dioxide (CO2)

  • Carbon monoxide (CO)

  • Dinitrogen hexoxide (N2O6)

  • Iodine tribromide (IBr3)

  • Xenon tetrafluoride (XeF4)

  • Disulfur decafluoride (S2F10)

  • Carbon tetrachloride (CCl4)

  • Boron trifluoride (BF3)

  • Water (H2O)

  • Ammonia (NH3)

  • Calcium fluoride (CaF2)

Page 8

Naming Binary Covalent Compounds

• Naming pattern:

  • Name of least electronegative element + stem of more electronegative element + suffix -ide

• Greek prefixes indicate the number of each type of atom.

• Note: Mono is omitted when it is at the beginning of the name.

Page 9

Examples of Naming Binary Covalent Compounds

• SO2 (Sulfur Dioxide)

• XeF6 (Xenon Hexafluoride)

• H2O is systematically named Dihydrogen Monoxide (Water).

Page 10

Naming Practice

• Name compound P3Br4:

  • Choices include:

    • Phosphorus bromide

    • Diphosphorus dibromide

    • Triphosphorus tetrabromide

    • Phosphorus tetrabromide

Page 11

Confirmation of Naming Practice

• Correct answer for naming P3Br4 confirmed through options provided.

Page 13

Polyatomic Ions

• Polyatomic ions: Groups of covalently bonded atoms with a net charge.

• Most common polyatomic ions are negatively charged.

• Adjustments made to Lewis structures based on charge:

  • Add an electron for each negative charge.

  • Subtract an electron for each positive charge.

• Key polyatomic ions to remember:

  • Sulfate SO4^2-

  • Phosphate PO4^3-

  • Nitrate NO3^-

  • Hydroxide OH-

  • Carbonate CO3^2-

  • Ammonium NH4^+

Page 14

Examples of Formulas for Ionic Compounds with Polyatomic Ions

• K2CO3 (Potassium Carbonate)

• CaSO4 (Calcium Sulfate)

• (NH4)3PO4 (Ammonium Phosphate)

Page 15

Writing Formulas of Ionic Compounds with Polyatomic Ions

• Process similar to writing binary ionic compounds:

  • Metal symbol first, followed by polyatomic ion.

  • Ensure equal positive and negative charges are represented.

  • Use parentheses when more than one polyatomic ion is needed.

Page 16

Naming Ionic Compounds with Polyatomic Anions

• Pattern for naming:

  • Name of metal + name of polyatomic anion.

• Examples include:

  • NaNO3 (Sodium Nitrate)

  • K2CO3 (Potassium Carbonate)

  • MgSO4 (Magnesium Sulfate)

  • Ca3(PO4)2 (Calcium Phosphate)

  • Cr(OH)4 (Chromium (IV) Hydroxide)

  • (NH4)2CO3 (Ammonium Carbonate)

Page 17

Naming Practice for Various Compounds

• Name compounds: FeS, Fe2(SO4)3, CS2

• Several naming options provided for review.

Page 20

Shapes of Molecules and Polyatomic Ions

• Most have three-dimensional shapes known as electronic group geometry.

• VSEPR theory used to predict shapes based on electron pairing in valence shells.

Page 21

VSEPR Theory Rules

• Two key rules in VSEPR theory:

  • Rule 1: All valence-shell electron pairs behave the same regardless of bonding or nonbonding.

  • Rule 2: Treat multiple bonds as single pairs in shape prediction.

Page 22

Arrangements of Electron Pairs

• VSEPR theory applicable to molecules or ions with up to six pairs of electrons.

• Focus will be limited to molecules with no more than four pairs.