States of MatterSolids

Matter•The state of matter tells you whether a material is a solid, liquid, or a gas. •Matter is anything that takes up space and has mass.

Atoms•An atom is the smallest particle of a given type of matter that still remains that matter.

Elements•Elements are atoms of the same type of

matter.

Molecules•Molecules are atoms or elements that are chemically bonded together. •Examples include H2O, CO2, NaCl

What makes a solid a solid? A liquid a liquid?

A gas a gas?•The physical state of a type of matter depends on how its atoms and molecules are arranged, and how they move.

Kinetic Theory of Matter•The energy of moving particles is kinetic energy.•The idea that the particles of all matter are in constant, random motion is the Kinetic Theory of Matter.

Temperature and Heat•The temperature of a material is an indirect measure of the average kinetic energy (Heat Energy) of the particles that make up the material.•The higher the temperature, the faster the particles are moving (more energy).•The lower the temperature, the slower the particles are moving (less energy).

Absolute Zero•It’s impossible to get there.•The temperature at which all particles stop movement is known as Absolute Zero. •Absolute Zero is -273.15⁰C

Transfer of Energy•Higher temperature particles (more energy) collide with lower temperature particles (less energy) transferring energy from high temperature to low temperature matter.•Example: Hot tea to ice tea, or a hot iron to your skin.

Matter in the Solid State•Water when frozen is ice, a solid. Because the ice is so cold the molecules are close together and have little movement. •When a solid has energy applied to it the molecules begin to shake more in all directions, but each molecule stays in place. •This is how the Kinetic Theory describes a solid - an arrangement of shaking particles.

Crystalline Solid•In some solids, particles are arranged in repeating geometric patterns. As more particles become part of a crystalline solid, the geometric pattern is repeated over and over. •Example: NaCl - table salt is cubic shape fig 4-5

Noncrystalline Solids•Some solids form without forming crystal structures. These solids cool very fast not allowing crystals to form, or the crystals that do form are in random arrangements not in repeating geometric patterns.•Noncrystalline Solids are sometimes called Amorphous Solids.•Examples: Glass and Plastics

How Does a Solid Become Liquid?

•If you have solid ice the molecules shake but stay in place. As heat energy is applied to the ice the molecules move faster until the molecules can no longer stay in position and break apart and become a liquid.

Melting Point•The temperature at which a solid becomes a liquid.•All solids have melting points usually at different temperatures.

Heat of Fusion•When a solid melts its temperature remains the same until all the solid becomes a liquid.•Example: Ice in a beaker is 0⁰C, as it begins to melt the water and the ice together remain 0⁰C, once all the ice is melted, then the temperature will begin to rise.•The point at which all the ice is melted and becomes a liquid is known as the heat of fusion of ice.

Freezing Point•As a liquid cools (loses energy) the particles slow down and come closer together. •Attractive forces begin to trap particles here and there and crystals form.•A liquids freezing point is the same as a solids melting point.•The temperature remains the same while crystals form and the Heat of Fusion is released.•After the liquid becomes all solid then the temperature can decrease more.

Viscosity•The resistance to flow is known as a materials Viscosity.•Example: Liquid glass as it cools it is less able to flow as it become solid. •Example: Oil flowing down a ramp flows more slowly than water down the same ramp. So oil has a higher viscosity than water. Oil is resisting to flow more than water.

Liquids and Gases•Matter in the Liquid State. Particles that make up a liquid move more freely than particles of a solid. •The attractive forces between particles are strong enough to keep them close together but not strong enough to hold them in fixed positions.

Forces Between Molecules

•Cohesion•Adhesion

•Surface Tension

Cohesion•Cohesion is the attractive force between water molecules that causes the molecules to pull in all directions toward each other.

Adhesion•Adhesion is the attractive force between two different molecules.•Adhesive forces are weaker than cohesive forces.

Surface Tension•Surface Tension is created by cohesive forces between molecules on the surface of water.•The water molecules pull inward toward the center of the water creating surface tension.

How Does a Liquid Become a Gas?

•A liquid gains energy to reach its boiling point. •Waters boiling point is 100⁰C•At the boiling point both water and steam can exist.•Steam is water vapor a gas.

Heat of Vaporization•The amount of energy required to change a liquid to a gas is called the liquids heat of vaporization.

Evaporation•Evaporation can occur at any temperature.•Vaporization occurs only at the boiling point of a liquid.

Evaporation and

Surface Area•The greater the surface area, the faster evaporation takes place.•Water molecules escape into the air from the surface of water.

Evaporation is a Cooling Process

•Water on your skin escapes into the air pulling heat away from your body. A cooling process.

Condensation•As a gas cools, its particles slow down and come closer together (condensing) forming water droplets.

Behavior of Liquids and Gases

Diffusion•Diffusion is the mixing of particles in fluids.•Diffusion of molecules occurs from areas of high concentration to areas of low concentration. •A Fluid is matter with the ability to flow. Gases and liquids are fluids.

Pressure•Pressure is the amount force applied to an area.•P= F⁄A

Pascal’s Principle•Pascal’s Principle states that pressure applied at any point to a confined fluid is transmitted unchanged throughout the fluid.•Example: toothpaste tube squeezed at any point is applying pressure to all the molecules in the fluid equally.

Gas Pressure•Gas is easy to compress because molecules are far apart. Solids and liquids are more difficult to compress because the molecules are closer together.

Atmospheric Pressure•Atmospheric pressure is all the Stuff above you pressing down on you.•Atmospheric pressure is less as you ascend up a mountain. •The higher you go up, less molecule are above you creating less air pressure.

Density •Density is the mass per unit of volume.•D=M/V•Density is the amount of matter in a specific amount of volume.•Example: A full shopping cart compared to an empty shopping cart. The full cart has more mass, stuff inside the cart, compared to the empty cart, with less stuff in the cart.

Buoyancy•Archimedes’ Principle states that when an object is placed in a fluid, the object weighs less by an amount equal to the weight of the displaced fluid.•The net upward force caused by the displaced fluid is called the buoyant force.•A decrease in weight is caused by the buoyant force when you float in a pool.