Grade 7 Science: Thermal Energy, Temperature, and States of Matter

Flashcards covering thermal energy, temperature scales, particle theory, states of matter, and phase changes from Science 7 Modules 3 Topics 1, 2, 4, and 5.

Thermal Energy / Heat (Chaleur)

The form of energy transferred from a substance at a higher temperature to a substance at a lower temperature.

Open Fires (Feux à ciel ouvert)

An early method for obtaining thermal energy that presents significant hazards, including burns, uncontrolled fire spread, and inhalation of smoke and toxic gases.

Traditional Wood Stoves (Poêles à bois)

Heating appliances historically designed to serve two vital domestic functions: heating living spaces and cooking food.

Clothes Dryer (Sécheuse à linge)

A household appliance invented to dry wet garments rapidly using controlled heat, independent of outdoor weather conditions.

Metallurgy (Métallurgie)

The science and technology of processing, extracting, and refining metals from ores to manufacture tools and structures.

Thermometer

An instrument calibrated to measure temperature quantitatively.

Air Thermometer

An early temperature-measuring instrument that operated on the expansion and contraction of heated and cooled air, invented by the Italian scientist Galileo Galilei.

Centigrade Scale

An alternative historical name for the Celsius temperature scale, named because it is divided into $100$ equal degree intervals between the freezing point and boiling point of water.

Atmospheric Boiling Point Variation

The phenomenon where water boils at a temperature below $100\,^{\circ}\text{C}$ at the top of a mountain due to reduced atmospheric pressure.

Absolute Zero

The lowest possible theoretical temperature where particle motion ceases, defined as $0\,\text{K}$ on the Kelvin scale and equal to $-273.15\,^{\circ}\text{C}$ (or approximately $-273\,^{\circ}\text{C}$).

Common Reference Temperatures (Figure 3.8)

Standard benchmark temperatures on the Celsius and Kelvin scales: water freezes at $0\,^{\circ}\text{C}$ ($273\,\text{K}$), room temperature is approximately $20\,^{\circ}\text{C}$ ($293\,\text{K}$), human body temperature is approximately $37\,^{\circ}\text{C}$ ($310\,\text{K}$), and water boils at $100\,^{\circ}\text{C}$ ($373\,\text{K}$).

Thermocouple

A temperature sensor made of two dissimilar metals bonded together that produces an electrical voltage when heated; useful for measuring very high temperatures, though less sensitive to minor fluctuations.

Bimetallic Strip / Thermostat

A device composed of two different metals that expand at different rates, causing the strip to bend with temperature changes to open or close an electrical switch.

Infrared Thermograph

An instrument that detects invisible infrared radiation ($\text{IR}$) emitted by objects and converts it into a visual color-coded thermal image.

Infrared (IR)

Electromagnetic radiation with wavelengths longer than visible red light, emitted by warm objects as radiant heat.

Thermal Expansion (Dilatation thermique)

The increase in the volume of a substance caused by heating, which makes its constituent particles move faster and spread farther apart.

Thermal Contraction (Contraction thermique)

The decrease in the volume of a substance caused by cooling, which causes its constituent particles to lose kinetic energy and draw closer together.

Pure Substance (Substance pure)

A sample of matter consisting of only one type of particle with uniform and constant chemical properties throughout.

Solid State

The state of matter that maintains its own fixed shape and volume, settles firmly, and is virtually incompressible.

Liquid State

The state of matter that has a definite volume but an indefinite shape, taking the shape of the bottom of its container while resisting compression.

Gaseous State

The state of matter that has neither a definite shape nor a definite volume, expanding to fill the entire container and being easily compressible.

Heat Capacity (Capacité thermique)

The total amount of thermal energy required to raise the temperature of an entire object or body by $1\,^{\circ}\text{C}$.

Specific Heat Capacity (Chaleur massique)

The specific quantity of thermal energy needed to raise the temperature of exactly one unit of mass ($1\,\text{g}$ or $1\,\text{kg}$) of a substance by $1\,^{\circ}\text{C}$.

Melting / Fusion (La fonte / La fusion)

The phase change in which a substance transitions from a solid state to a liquid state through the absorption of thermal energy.

Freezing / Solidification (La congélation / La solidification)

The phase change in which a substance transitions from a liquid state to a solid state by releasing thermal energy.

Evaporation (L'évaporation)

The phase transition of a substance from a liquid state into a gaseous state occurring at the surface of the liquid.

Sublimation (La sublimation)

The phase transition where a substance passes directly from a solid to a gas, or directly from a gas to a solid (deposition), without entering the liquid state.

Evaporative Cooling (Refroidissement par évaporation)

A process in which higher-energy surface liquid particles evaporate into gas, reducing the average kinetic energy and temperature of the remaining liquid, such as when sweat cools human skin during physical exercise.

Latent Heat / Phase Change Energy

Thermal energy absorbed or released by particles during a change of state that alters particle arrangement and spacing without changing the temperature of the substance.