Science Grade 7 - Unit 3: Heat and Temperature
Who invented the early thermometer?
Galileo Galilei
A series of equally measured sections that are marked and numbered for use in measurement
scale
what is the boiling point of water
100°C
what is the freezing point of water
0°C
what happens when water has lower pressure
it boils at a lower tempurature
what happens when water has higher pressure
it melts at a lower temperature
what happens when you add salt to water
the freezing point of water lowers
adding salt to water to lower the freezing point
impurities
a scale used to explain the behavior of gases
Kelvin
the coldest possible temperature on the Kelvin scale
absolute zero (0 Kelvin) or -273.15°C
a material which is affected by changes in the environment (such as temperature)
sensor
what the sensor produces and what affects the responder
signal
a pointer, light, or other mechanism that uses the signal in some way
responder
functions of a thermometer (3 in order)
sensor → signal → responder
wires made up of two different metals which are twisted together that can measure higher temperatures than a thermometer can
thermocouple
3 examples of things that thermocouples are used in
kilns, diesel engines, and industrial furnaces
2 examples of things that bimetallic strips are used in
thermometers and furnaces
a bimetallic strip connected to a writing device and paper which records temperature fluctuations over time
recording thermometer
records infrared radiation as different colors according to their temperature. It senses the amount of heat in surrounding objects
infrared thermogram
how many different types of atoms are there found on the Periodic Table
92
has a definite shape and volume
solids
has a definite volume but the shape varies depending on the container
liquids
takes on the shape and volume of its container
gases
the Particle Model of Matter (4 points)
• all substances are made of particles too small to see
• the particles are always in motion
• the particles have space between them
• when motion of particles increases, so does the temperature
in what way does energy always transfer
from a high energy source to a low energy source (hot to cold)
energy generated by the movement of particles
thermal energy (total kinetic energy)
a measure of the average speed of energy of the particles' motion in a material
temperature
the total energy or all the particles in a material (2 terms)
thermal energy or heat
to decrease in volume
contract
to increase in volume
expand
what causes things to expand and contract
temperature changes
what temperature usually causes contraction
cooling
the amount of thermal energy that warms or cools an object by 1 degree Celsius
heat capacity
the amount of thermal energy that warms or cools 1 GRAM of a material by 1 degree Celsius
specific heat capacity
solid to liquid
melt
liquid to solid
freeze
liquid to gas
evaporate
gas to liquid
condense
solid to gas
sublimation
gas to solid
deposition
a process in which the faster moving particles on the surface of a liquid evaporate and escape into the air, the slower ones are left behind creating a lower average kinetic energy (cooling it)
evaporative cooling
which temperature of particles are more organized
cold
which temperature of particles are less organized
hot
the 3 ways of transferring energy
• radiation
• conduction
• convection
the 4 different types of energy sources
• chemical
• electrical
• mechanical
• nuclear
released in the form of thermal energy when it is burned
chemical energy
the energy of a moving object
mechanical energy
the energy of charged particles
electrical energy
energy we get from the Earth's interior
geothermal energy
uses materials in a structure to absorb, store, and release solar energy
passive solar heating
uses mechanical devices to distribute stored thermal energy
active solar heating
uses stored water or air on a building's roof, heats it, and then pumps it through the building
solar collectors
what are 2 problems with fossil fuels
they are non-renewable (will run out) and they give off carbon dioxide which contributes to global warming
uses waste from thermal pollution to produce electricity or uses the waste to heat buildings
cogeneration
3 harmful chemicals that are released when burning fossils fuels
• carbon dioxide (CO2)
• sulfur dioxides (SO2)
• carbon monoxide (CO)