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Heat (energy)...
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Question | Answer | ||||||
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Elements don't | split into any-thing | simpler through | Chemical methods as they only contain 1 of 1 kind of | atom. | |||
Heat is a type of | energy, specifically | kinetic energy possessed by | particles. | ||||
Heat ENERGY is measured in | joules (J). The amount of joules in a kilojoule(KJ) is | 1000. | |||||
If something gains a lot of heat energy, it (can) become | hot. | ||||||
The measure of how hot or cold an object is, known as | temperature. | ||||||
Usually temperature is measured in | degrees Celsius (ºC). | ||||||
At 1 atm the freezing point of water is defined as | 0ºC and the boiling point of water is defined at | 100ºC. Atm is an abbreviation of | atmosphere and is a unit of | pressure based on the average atmospheric pressure at | sea level. | ||
In terms of newtons per centimeter squared, 1 atm (atmosphere) is equal to | 10.1325 newtons per centimeter². | ||||||
Temperature can be measured by a variety of different thermometers. These include liquid in | glass, d.... | igital, therm.... | ocouple and bimetal | strip thermometers. | |||
The correct phrase for heat transfer is | ‘thermal transfer’. | ||||||
Heat energy can be transferred by four processes, which in alphabetical order are: | conduction, convection, evaporation and radiation. In each process, thermal energy is also transferred in the way: | hot to cold. | |||||
Heat energy only flows when there is a | temperature difference. | ||||||
Substances may be made up of | particles, one of the 3 from | atoms, ions or molecules.To each other, these particles are | attracted. They move around meaning that they have | kinetic energy. The kinetic energy of particles increases with | temperature. | ||
Metals are good conductors of heat because: inside metals there are both | atoms and electrons.The free electrons can move around and | vibrate. The heat energy is passed on by neighbouring | particles | vibrating along the | metal. | ||
In metals through vibrations, neighbouring particles pass on so called; | 'heat energy'. | ||||||
Non-metals are poor conductors of | heat. In a non-metal, heat energy is only passed on by neighbouring | particles | vibrating along the | non-metal as there are no | free electrons. | ||
Non-metals are poor conductors of | heat. In a non-metal, heat energy is only passed on by neighbouring | particles | vibrating along the | non-metal as there are no | free electrons. | ||
Poor conductors of heat are known as | insulators. | ||||||
Liquids and gases are poor conductors of | heat and therefore good | insulators. | |||||
Apart from non-metals,liquids, solids and gas an insulator of heat is a | vacuum. | ||||||
When substances are mixed; they settle in order of | density with the least dense at the | top. | |||||
Density depends on how far apart | particles are. | ||||||
With convection currents, heat rises to the | top then seperates(sometimes.) in directions that are | opposite as it begins to | cool. As it gets to the bottom, the current then begins to | heat up before returning to its | starting point and afterwards the cycle is | repeated. | |
Convection currents do not occur in | solids because the particles are held in fixed | positions. | |||||
Two states in which convection currents can occur are | liquids and gas. | ||||||
Heat can move by travelling as | infrared waves. Like light waves, these are | electromagnetic waves, but with a longer | wavelength. As infrared waves act like light waves, they can travel through a | vacuum but not objects that are | opaque. They can also be | reflected and travel at approximately | 300,000,000m/s. |
Black absorbs more heat than white as it is a lack of | colour and absorbs all frequencies of 'visible | light' and all colours in the | 'spectrum'. That energy stores up alongside | heat, effectively | radiating it. | ||
White (supposedly) absorbs all | frequencies and | light but does not radiate | heat. | ||||
At a cold enough temperature, even substances that are normally gases may become | solid. Super heated gas is | plasma. | |||||
As long as they don’t catch fire or decompose first, at higher temperatures, solids change to become either | liquids or gases. | ||||||
If a solid is heated, its temperature rises until the solid reaches its | melting point. At the melting point, the temperature stops rising whilst the solid | melts. This is because heat energy is going into separating the | particles rather than | raising the temperature. Once all the solid has melted, the temperature once again starts to | rise until it reaches the | boiling point. As energy goes into further separating the particles, at the boiling point the rising of the temperature | stops. |
Evaporation occurs when the particles in a | liquid | escape to form a | vapour. The particles that escape take some | energy from the remaining | particles and so the temperature of the liquid | falls. | |
Evaporation can occur at any | temperature but it occurs most rapidly at a liquid’s | boiling point. Evaporation is also another method of | thermal transfer. | ||||
Radiation is the transfer of | thermal energy by | electromagnetic waves, which does not need a | medium. | ||||
A material that does not allow heat energy to flow through it is known as an | insulator. | ||||||
The transfer of heat energy is known as | heating. | ||||||
Convection is the way that heat | energy travels through both | liquids and gases because their particles are free to | move, and take the place of particles with less | ||||
The way that heat energy travels through solids because their particles are close together is known as | conduction. When a substance is heated, its particles gain | energy and [] more vigorously | vibrate more vigorously. The particles bump into nearby | particles and make them [] more | vibrate more. This passes the thermal energy through the substance by | ||
A material that allows heat energy to flow through it is known as a | conductor. | ||||||
At the melting point of a substance, the point of attraction gets | weaker. | ||||||
Usually when objects are heated; they | expand and when they are cooled (with the exception of water) substances usually | contract. | |||||
Substances that allow thermal energy to move through them easily are called | conductors. | ||||||
Substances that do not allow thermal energy to move through them easily are called | insulators. | ||||||
'All' objects transfer thermal energy by [] [] | infrared radiation. The infrared radiation. The hotter an object is, the more [] [] it gives off | infrared radiation it gives off. No p[] are involved in radiation, unlike conduction and convection | particles. (Infrared cameras give images even in the dark, because they are detecting heat, not visible light.) | ||||
Non-metals are poor conductors of | heat. In a non-metal, heat energy is only passed on by neighbouring | particles | vibrating along the | non-metal as there are no | free electrons. This allows a flow of | energy from | hot to cold. |