Physical Science Chapter 9

State of Matter: gas

no fixed shape, no fixed volume --attractive forces are so weak that particles no longer cling to one another --contains mostly empty space --particles free to move in all directions until they have spread out evenly throughout the container --density of a gas is less than the density of solids or liquids

thermal energy

sum of the kinetic energy and potential energies of all the particles in an object **thermal energy = Kinetic energy + Potential Energy TE = KE + PE

thermal conductors

materials that conduct heat easily example: metals (aluminum, copper, silver, gold)

kinetic theory

matter is made of particles that are atoms, molecules or ions that are always in random motion, moving at different speeds and in all directions

entropy

measure of how spread out or dispersed energy is --increases when thermal energy becomes more spread out

temperature

measure of the average kinetic energy of its particles --particles in matter move at various speeds and have different kinetic energies

melting

Change of state from a solid to a liquid with the addition of energy (forces become weaker)

States of Matter

Four states of matter: solid, liquid, gas, and plasma Differences are due to differences in the attraction between particles

Second Law of Thermodynamics

In order for thermal energy to flow from a cool object to a warmer object, work must be done --thermal energy cannot be converted COMPLETELY into work

Conversion of Kelvin to Celsius

Kelvin = degrees in Celsius 273 or degrees in Celsius = Kelvin - 273

Celcius (C)

Metric temperature scale on which water freezes at 0 degrees and boils at 100 degrees

Kelvin (K)

SI Unit for temperature

heat of vaporization

The amount of energy required to change 1kg of a substance from a liquid to a gas

condensation

The change of state from a gas to a liquid --the heat of vaporization = the amount of energy released during condensation

vaporization

The change of state from a liquid to a gas as the temperature of a liquid increases --particles in gas state have more energy than in the liquid state

freezing

The change of state from a liquid to a solid

First Law of Thermodynamics

The increase in the thermal energy of a system equals the work done on the system plus the thermal energy added to the system

thermal contraction

a decrease in a material's volume when the temperature is decreased

heating curve

a diagram that shows the temperature changes and changes of state of a substance as it is heated

thermal insulator

a material in which thermal energy moves slowly **a material that reduces the flow of thermal energy by conduction, convection, radiation --used to control the flow of thermal energy examples: wood, fiberglass, some plastic, and air (gases)

Fahrenheit (F)

a scale of temperature on which water freezes at 32° and boils at 212° under standard conditions

thermal expansion

an increase in the size of a substance in response to an increase in the temperature of the substance

temperature and matter

as the average speed of particles in random motion increases, the temperature of the substance increases. EXAMPLE: particles in hot tea move faster that those in iced tea

Kinetic Theory of Matter

describes the motion of particles in matter --atoms and molecules that make up matter are in constant motion

calorimeter

device used to measure specific heat of a material

Changing states of matter

caused by changes in thermal energy of a material --most matter EXPANDS when heated

Equation: change in thermal energy

change in thermal energy (J) = mass (kg) x change in temperature (*C) x specific heat (J/kg *C)

Ways to transfer thermal energy (heat transfer)

conduction, convection, radiation

density

density = mass/ volume of a sample matter

State of Matter: solid

fixed shape and fixed volume -- particles are packed closely together and are constantly vibrating in place --matter where particles are arranged in a fixed location

State of Matter: liquid

fixed volume; no fixed shape --weaker attractive forces; particles slide past each other

State of Matter: plasma

no fixed shape; no fixed volume --made of positively and negatively charged particles ==gaslike mixture with no definite volume or shape --found in the Sun and stars, lightning bolts, neon and fluorescent tubes, and auroras **most common state of matter in Universe

diffusion

particles in a gas spreading throughout a given volume until evenly distributed

Thermodynamics

study of the relationship between thermal energy, heat, and work

specific heat (J/kg *C)

the amount of thermal energy needed to raise the temperature of 1 kg of some material by 1 degree Celsius note: specific heat of water is higher than most materials; water warms more slowly as thermal energy is added to it

heat of fusion

the energy required to change 1kg of a substance from solid to liquid at its melting point

convection currents

the upward movement (rising) of warm material and the downward movement (sinking) of cool material

heat (J)

thermal energy that flows from something at higher temperature to something at lower temperature. --form of energy

radiation

transfer of energy by electromagnetic waves that travel through space even if no matter is present --does not require matter example: energy from Sun traveling to Earth

conduction

transfer of thermal energy between colliding particles --occurs in solids, liquids, and gases --metals are best conductors of heat

convection

transfer of thermal energy in a fluid by the movement of warmer and cooler material **most easily occur in liquids and gases --how wind and ocean currents are formed

boiling

vaporization that occurs on and below the surface of a liquid or throughout the liquid

evaporation

vaporization that takes place only on the surface of a liquid

kinetic energy

when particles collide, kinetic energy can be transferred from 1 particle to another and the direction of particle motion changes