Lesson 12.2 and 12.4

Laws of Attraction

Phase Change

Intramolecular Forces

Force Model Basis Example

Ionic Cations and anions

NaCl

Covalent Shared electrons H2

Metallic Metal cations and mobile electrons

Fe

Dispersion Forces

Weak Force

Temporary shift in electron density clouds

Explains State of Matter of Halogens

Small to Large

F2 (g)

Cl2 (g)

Br2 (l)

I2 (s)

Dipole-dipole Forces

Permanent forces

Positive – Negative Poles

Hydrogen Bonds

Dipole-dipole attraction

some examples large

electronegative

H-F H-O

H-N H-S

Room TemperatureH2O is liquid NH3 is gas

Questions

Explain what determines a substance’s state at a given temperature.

Compare intermolecular and intramolecular forces.

Which molecules can form hydrogen bonds?

a. H2 b. H2S c. HCl d. HF

Questions

Explain what determines a substance’s state at a given temperature.

Intermolecular forces – solid very strong, liquid weaker, gas has none

Compare intermolecular and intramolecular forces.

Intramolecular hold particles together, intermolecular between particles

Which molecules can form hydrogen bonds?

a. H2 b. H2S c. HCl d. HF

Phase Change

Phase Changes that Require Energy

Melting – liquid is warmer than ice, heat is transferred

Vaporization – liquid to vapor or gas gradually

Sublimation – direct from solid to gas

Phase Change Release Energy

Freezing – heat is removed

Condensation – what happens to the glass of ice cold lemonade on a hot day?

Phase Diagram

Triple Point

Phase Diagram Questions

Explain what the triple point and the critical point on a phase diagram supplies

Determine the phase of water at 75.00 C and 3.00 atm.

Explain what the triple point and the critical point on a phase diagram supplies

Triple point is where all 3 phases can coexist.

Critical point is temp and pressure above which a substance is not a liquid

Determine the phase of water at 75.00 C and 3.00 atm. liquid

Questions

Explain how the addition or removal of energy can cause a phase change.

Explain the difference between the processes of melting and freezing.

Compare disposition and sublimation.

Questions

Explain how the addition or removal of energy can cause a phase change.

Add Energy, increase Kinetic Energy, less intermolecular forces

Remove Energy, decrease Kinetic Energy, increase intermolecular forces

Explain the difference between the processes of melting and freezing.

Freezing: Liquid to solid, release EnergyMelting: Solid to liquid, need to input EnergyCompare disposition and sublimation.Sublimation: solid to vapor directly, skips

liquid phaseDisposition: Vapor to solid, without liquid

phase