Notes 13 1 and 13 3 OBJECTIVES Students

Notes: 13. 1 and 13. 3 • OBJECTIVES: Students will be able to (SWBAT) 1. Explain how intermolecular forces affect states of matter • QUESTIONS TO PONDER: 1. How does the kinetic molecular theory affect atoms and molecules? 2. How are the actions of particles different between gases, liquids and solids? 3. Which interactions or forces would most likely be found in each type of state (gas, liquid and solid)? 4. How is viscosity and surface tension affected by IMFs? 5. How do the 4 types of solids differ in their interactions?

Gases (13. 1) • Kinetic molecular theory explains gas behavior, especially in motion – Kinetic energy is energy of motion – Particles are always in motion

Properties of Gases • • • Particles are spaced far apart (low density) Particles have low attraction to each other Have fluidity (ability to flow) Are compressible (can be squeezed) Have fastest and most random motion

Moving gas particles…

Compression and Expansion EXPANSION COMPRESSION movable pistons gas cylinders

Diffusion - Gas particles move to be evenly distributed - Particles diffuse because of random motion

Heat affects motion • Heat (energy) increases kinetic energy – Warmer particles moving faster – Cooler particles moving slower

Liquids and Solids (13. 3) • Review: 3 States of Matter – solid, liquid and gas

Just add (or take away heat)… Which state has the strongest intermolecular attractions? REMOVE HEAT

States of Matter and Intermolecular Forces (IMFs) • Stronger the IMF particles will be more compacted (close together) – Strongest solids • ionic bonds • covalent network bonds • At very low temperatures, most substances can be solids – Liquids • mostly polar (dipole-dipole) interactions • Heavy, non-polar molecules – Weakest gases • nonpolar molecules • If temperature is high enough, most can be gases

Properties of Liquids • Liquids – Denser than gases (more compact) – Ability to flow

Viscosity • Resistance of a liquid to flow because of IMFs – High viscosity thick flows more slowly • Honey, syrup – Low viscosity more “liquidy” flows more rapidly • Water, many other liquids – As temperature increases, viscosity will decrease (flows faster) less IMF because particles are farther apart

Surface Tension • Surface of liquid sticking together (cohesiveness) due to IMFs • The reason why drops of liquid form • molecules at or near the surface tend to contract the surface into smallest possible area

Properties of Solids • Solids – Densest state (particles packed close together) – Not very compressible (hard to squeeze further) – Solid particles do move they vibrate in place

Types of Solids: Crystals • crystalline solids: particles arranged in a geometric, 3 -D structure – Ionic crystals: ions in lattice structure (salts) – Molecular crystals: molecules in lattice structure (ice any molecule if cold enough) – Metallic solids: metal atoms held together by metallic bonds in a sea of electrons (any solid metals) – Covalent network solids: nonmetal atoms held together in repeating pattern by covalent bonds which are very strong (diamonds)

Types of Solids: Crystals • crystalline solids: particles arranged in a geometric, 3 -D structure INTER or BOND TYPE DESCRIPTION INTRA IONIC Ions form lattice structure salts METALLIC Metal atoms held by “sea of electrons” COVALENT Non-metal elements held tightly by covalent bonds (e. g. diamonds) BETWEEN COVALENT MOLECULES Distinct (separate) molecules held together by IMFs (dipole-dipole, London, H-bond)

Types of Solids: Crystals • crystalline solids: particles arranged in a geometric, 3 -D structure INTER or BOND TYPE DESCRIPTION INTRA IONIC Ions form lattice structure salts INTRA METALLIC Metal atoms held by “sea of electrons” INTRA COVALENT Non-metal elements held tightly by covalent bonds (e. g. diamonds) INTRA BETWEEN COVALENT MOLECULES Distinct (separate) molecules held together by IMFs (dipole-dipole, London, H-bond) INTER