Unit 1: States of Matter and Kinetic Energy

Identify the following phase change and explain what happens at the molecular level for evaporation to occur.

Evaporation happens when atoms or molecules escape from the liquid and turn into a vapor. Not all of the molecules in a liquid have the same energy.

Identify these properties of liquids; Molecular or atomic arrangement, Kinetic energy, Compressibility, Thermal expansion, Viscosity, Cohesion, Adhesion, Hydrogen bonding, Surface tension, and Brownian motion.

Arrangement: liquid are close together with no regular arrangement Kinetic energy: Liquids have more kinetic energy than solids. When a substance increases in temperature, heat is being added, and its particles are gaining kinetic energy. Because of their close proximity to one another, liquid and solid particles experience intermolecular forces. Compressibility: Liquids are compressible, but only to small degree and/or with very high pressure Thermal expansion: The behavior of gasoline pumped on a hot day provides an example of liquid thermal expansion in response to an increase in temperature. When it comes from its underground tank at the gas station, the gasoline is relatively cool, but it will warm when sitting in the tank of an already warm car. If the car's tank is filled and the vehicle left to sit in the sun, the gasoline might very well expand in volume faster than the fuel tank, overflowing onto the pavement. Viscosity: Viscosity is another type of bulk property defined as a liquid's resistance to flow. When the intermolecular forces of attraction are strong within a liquid, there is a larger viscosity. Cohesion: Cohesive forces are the intermolecular forces which cause a tendency in liquids to resist separation. These attractive forces exist between molecules of the SAME substance. Adhesion: As liquids flow they adhere to the surface they are traveling across - especially when the surface is curved or round. Between two DIFFERENT substances. Hydrogen bonding: Hydrogen bonding forms in liquid water as the hydrogen atoms of one water molecule are attracted towards the oxygen atom of a neighboring water molecule; generally, a proton shared by two lone electron pairs. Surface tension:the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of the water molecules. Surface tension allows insects, usually denser than water, to float and stride on a water surface. Brownian motion: the random motion of particles suspended in a fluid (a liquid or a gas) resulting from their collision with the fast-moving atoms or molecules in the gas or liquid

Identify these properties of gases; Molecular or atomic arrangement, Kinetic energy, Compressibility, Brownian motion and Thermal expansion.

Arrangement: no pattern; all over the place Kinetic energy: very high because the forces are weak; therefore, the particles can move all over Compressibility: easiest to compress compared to a liquid or solid Brownian motion: the random motion of particles suspended in a fluid (a liquid or a gas) resulting from their collision with the fast-moving atoms or molecules in the gas or liquid. Thermal expansion: Molecules within gases are further apart and weakly attracted to each other. Heat causes the molecules to move faster, (heat energy is converted to kinetic energy) which means that the volume of a gas increases more than the volume of a solid or liquid.

Identify these properties of solids; Molecular or atomic arrangement, Kinetic energy, Compressibility, and Thermal expansion.

Arrangement: very tightly packed, usually in a pattern Kinetic energy: lowest of all three states Compressibility: least compressible Thermal expansion: atoms vibrate faster about their fixed points but do not have much room to expand because they have strong bonds

Identify the following phase change and explain what happens at the molecular level for deposition to occur.

Deposition occurs when a gas becomes a solid without going through the liquid state of matter. Those little frost crystals on plants build up when water vapor from the air becomes a solid on the leaves of plants.

Identify the following phase change and explain what happens at the molecular level for sublimation to occur.

In sublimation, the particles go directly from the solid crystal to the gas without melting.

Explain what the kinetic theory of matter is and how it determines state of matter.

Kinetic energy is energy that an object has because of its motion. All particles have energy, and the energy varies depending on the temperature the sample of matter is in, which determines if the substance is a solid, liquid, or gas. Solid particles have the least amount of energy, and gas particles have the greatest amount of energy.

Identify the following phase change and explain what happens at the molecular level for condensation to occur.

Occurs when gaseous water vapor turns to liquid. Condensation is the end result when warm air containing tiny molecules of water vapor has been cooled. As warm air rises within the atmosphere, cool air falls and the cooled water molecules condense. The condensed water molecules form liquid water droplets. This is why your cold glass of iced tea appears to sweat on a hot summer day.

Compare solids, liquids, and gases in terms of their properties and applications.

Particles in a: *gas are well separated with no regular arrangement. *liquid are close together with no regular arrangement. *solid are tightly packed, usually in a regular pattern. Particles in a: *gas vibrate and move freely at high speeds. *liquid vibrate, move about, and slide past each other. *solid vibrate (jiggle) but generally do not move from place to place.

Differentiate between kinetic energy and potential energy

Potential energy is stored energy in an object or system. Kinetic energy is when the object is in motion.

Identify the following phase change and explain what happens at the molecular level boiling to occur.

When boiling occurs, the more energetic molecules change to a gas, spread out, and form bubbles. These rise to the surface and enter the atmosphere.

Identify the following phase change and explain what happens at the molecular level for freezing to occur.

When water freezes, the water molecules have slowed down enough that their attractions arrange them into fixed positions. Water molecules freeze in a hexagonal pattern and the molecules are further apart than they were in liquid water.

Identify phase changes as being exothermic or endothermic processes.

solid -> liquid, melting, endo liquid -> gas, boiling, endo solid -> gas, sublimating, endo gas -> liquid, condensing, exo liquid -> solid, freezing, exo gas -> solid, condensing, exo