Chapter 7 Flashcards
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What is the minimum value on the Kelvin scale?
0 K
0 K is also known as absolute zero
What happens to particles of a substance as they approach absolute zero?
Particles slow down so much that they hardly move and their kinetic energy approaches 0 J
How do you convert from Kelvin to Celsius?
T_c = T_k - 273
How do you convert from Celsius to Kelvin?
T_k = T_c + 273
What is the melting point?
Temperature at which a solid changes to a liquid
What is the freezing point?
Temperature at which a liquid changes to a solid
What is the boiling point?
Temperature at which a liquid changes to a gas
What is the condensation point?
Temperature at which a gas changes to a liquid
True or False: The melting point and freezing point temperatures are equal.
True
True or False: The boiling point and condensation point temperatures are equal.
True
What is thermal energy?
Total potential and kinetic energy possessed by the particles of a substance
What is heat?
Transfer of thermal energy from a substance with a higher temperature to a substance with a lower temperature
What is thermal conduction?
Transfer of thermal energy that occurs when warmer objects are in physical contact with colder objects
What is thermal convection?
Transfer of thermal energy through a fluid that occurs when colder denser fluid falls and pushes up warmer less dense fluid
What is radiation in the context of thermal energy?
Movement of thermal energy as electromagnetic waves
What is specific heat capacity?
The amount of energy needed to raise the temperature of 1 kg of a substance by 1 °C
What is the specific heat capacity of water?
4.18 x 10^3 J/(kg *°C)
What is the specific heat capacity of vegetable oil?
2.0 x 10^3 J/(kg *°C)
What is the quantity of heat (Q)?
Total amount of thermal energy transferred from a warmer substance to a colder substance
What factors are considered in the quantity of heat calculation?
Mass (m), Specific heat capacity (c), Change in temperature (ΔT)
What is the equation for calculating quantity of heat?
Q = mcΔT
What happens to thermal energy when a warmer object comes in contact with a colder object?
Thermal energy is transferred from the warmer object to the colder object until thermal energy is evenly distributed
What is thermal expansion?
Increase in the volume of an object due to an increase in its temperature
What occurs during melting?
Absorbing thermal energy; particles move faster and farther apart
What occurs during freezing?
Releasing thermal energy; particles move slower and closer together
What occurs during boiling?
Absorbing thermal energy; particles gain enough kinetic energy to break away completely
What occurs during condensation?
Releasing thermal energy; particles bond together into a liquid
Fill in the blank: The principle of thermal energy exchange states that when a warmer object comes in contact with a colder object, thermal energy is ______.
transferred
What is a thermal conductor?
Material that allows thermal energy to pass through quickly and easily
What is a thermal insulator?
Material that does not allow thermal energy to pass easily
What is the best thermal insulator?
A vacuum
What happens to particles when they gain enough kinetic energy?
Particles gain enough kinetic energy to break away completely
This transition leads to the substance changing into a gas.
What occurs when a gas releases thermal energy?
Particles move slower and closer together, the substance cools, and its temperature decreases
Decreased particle speed strengthens forces of attraction between particles.
What is the condensation point?
The point at which bonds strengthen enough for the gas to become a liquid
At this stage, particles begin to cluster together.
What is the freezing point?
The point at which particles bond completely into a rigid structure, transitioning the substance into a solid
This process involves the release of thermal energy.
What is sublimation?
The direct change of a substance from solid to gas without becoming a liquid
An example is dry ice (solid carbon dioxide) turning into carbon dioxide gas.
What is deposition?
The reverse process of sublimation, where a gas changes directly into a solid
This can occur under certain conditions, such as temperature and pressure.
What do heating and cooling graphs illustrate?
They show how the temperature of a substance is affected by thermal energy absorption or release
The flat parts of the graphs indicate constant temperature during changes of state.
Why does temperature remain constant during a change of state?
Because thermal energy is used to change the potential energy of the substance’s particles, not their kinetic energy
This is why the temperature does not change despite energy absorption or release.
What is latent heat?
The total thermal energy absorbed or released when a substance changes state
Measured in joules.
Define latent heat of fusion.
The amount of thermal energy required to change a solid into a liquid or a liquid into a solid
Measured in joules per kilogram (J/kg).
Define latent heat of vaporization.
The amount of thermal energy required to change a liquid into a gas or a gas into a liquid
Measured in joules per kilogram (J/kg).
How is specific latent heat defined?
The amount of thermal energy required for 1 kg of a substance to change from one state into another
Measured in joules per kilogram (J/kg).
What is the formula to calculate latent heat during melting or freezing?
Q = mL_f
Where Q is the latent heat, m is mass in kg, and L_f is specific latent heat of fusion.
What is the formula to calculate latent heat during boiling or condensing?
Q = mL_v
Where Q is the latent heat, m is mass in kg, and L_v is specific latent heat of vaporization.
What is thermal energy?
The total quantity of kinetic and potential energy possessed by the atoms or molecules of a substrate
When an object absorbs thermal energy, it heats up; when it releases thermal energy, it cools down.
Why can’t we measure the total thermal energy of an object?
Because we can only measure the average kinetic energy of the particles, which indicates how hot or cold the object is
This is what temperature measures.
What happens to mercury in a thermometer placed in warm water?
Fast water particles transfer energy to the glass, causing mercury particles to speed up and rise
This indicates an increase in temperature.
What happens to mercury in a thermometer placed in cold water?
Fast mercury particles transfer energy to the glass, which passes it to the cold water, causing mercury to contract and move down
This indicates a decrease in temperature.
Name the three common temperature scales.
- Celsius Scale
- Fahrenheit Scale
- Kelvin Scale
Each scale has its own basis for measuring temperature.
What is the freezing and boiling point of pure water on the Celsius scale?
Freezing point: 0 °C, Boiling point: 100 °C
This scale is commonly used by weather forecasters and doctors.
What is the freezing and boiling point of pure water on the Fahrenheit scale?
Freezing point: 32 °F, Boiling point: 212 °F
This scale is primarily used in the United States.
What does the Kelvin scale measure?
The total amount of thermal energy that substances possess
It is used by scientists for precise measurements.
What is the max number of valence electrons an atom can have in the Bohr-Rutherford Model?
8
This is based on the octet rule, which states that atoms are most stable when they have eight valence electrons.
What are the components of an atom according to the Bohr-Rutherford Model?
- Protons
- Neutrons
- Electrons
- Nucleus
- Shells or Energy Levels
- Valence Electrons
How do you calculate the total number of neutrons in an atom?
Mass # (nucleons) – Atomic # (protons) = # of Neutrons
What is an isotope?
An isotope is a form of an element that has the same atomic number but a different atomic mass.
What distinguishes Carbon-12 from Carbon-14?
Carbon-14 has two more neutrons than Carbon-12.
What are the common forms of hydrogen isotopes?
- Protium (1 proton)
- Deuterium (1 proton, 1 neutron)
- Tritium (1 proton, 2 neutrons)
What is a radioisotope?
Radioisotopes are unstable isotopes that release energy as radiation during nuclear structure changes.
True or False: Radioisotopes can only be harmful and have no benefits.
False
Radioisotopes can be beneficial in medical imaging and treatment.
What is radioactive decay?
Radioactive decay is the spontaneous disintegration of an atom’s nucleus.
What is nuclear fission?
Nuclear fission is a reaction in which an atom’s nucleus splits into smaller parts, releasing energy.
What is the main difference between chemical and nuclear reactions?
Chemical reactions transform reactants into products without changing the identities of the elements, while nuclear reactions alter an atom’s nucleus.
What forces are involved in the stability of the nucleus?
- Electrostatic Force
- Strong Nuclear Force
What happens to the stability of the nucleus as atomic number increases?
Higher electrostatic force of repulsion requires more neutrons to maintain stability.
What occurs during alpha decay?
An alpha particle (2 protons and 2 neutrons) is spontaneously released from the nucleus.
What is transmutation in the context of nuclear reactions?
Transmutation is the process where a parent atom transforms into a daughter atom during radioactive decay.
What is beta-negative (β-) decay?
In β- decay, a neutron decays into a proton and an electron, which is emitted from the nucleus.
What is the effect on atomic number during beta-negative (β-) decay?
The atomic number increases by one.
What occurs during beta-positive (β+) decay?
A proton decays into a neutron and a positron, which is emitted from the nucleus.
What is electron capture?
Electron capture is a form of beta decay where an electron is absorbed by a nucleus and combines with a proton to form a neutron.
How does electron capture affect an element’s properties?
A process where the atomic number (Z) decreases by one while the mass number (A) remains unchanged.
It is a type of transmutation.
What is the half-life of aluminum-26?
720,000 years.
Used to date the age of interstellar and lunar rocks.
Why can’t carbon-14 dating be used for certain rocks?
Rocks are much older than the range of carbon dating.
Carbon-14 is effective for dating up to about 60,000 years.
What is nuclear power generation?
The process of generating energy through nuclear reactions, often involving fission.
Controversial due to radioactive waste and potential meltdowns.
What is the significance of Einstein’s equation E=mc²?
It demonstrates the mass-energy equivalence, showing that mass and energy are interchangeable.
E is energy, m is mass, and c is the speed of light.
What does the law of conservation of mass-energy state?
The total mass-energy in an isolated system remains constant.
Mass can transform into energy and vice versa.
What is the atomic mass unit (u)?
A unit of mass equal to one-twelfth of a carbon-12 atom.
Equivalent to approximately 1.66×10⁻²⁷ kg.
What is binding energy?
The energy required to separate nucleons in the nucleus.
It explains the mass defect in atoms.
How much energy does one mega-electron volt (MeV) represent?
1.602×10⁻¹³ joules.
One MeV is one million electron-volts.
What is nuclear fission?
The process of splitting a heavy nucleus into smaller elements, releasing energy.
Commonly involves isotopes like uranium-235.
What is critical mass?
The amount of fuel needed for a chain reaction to occur.
Essential for sustaining nuclear fission.
What is neutron moderation?
The process of slowing down neutrons to sustain a chain reaction in nuclear reactors.
Achieved using materials like heavy water.
What is gamma decay?
A process where an excited nucleus releases energy as a gamma ray.
The parent and daughter nuclei remain identical in mass and atomic number.
What is nuclear fusion?
A nuclear reaction where two atomic nuclei fuse to form a larger nucleus.
Powers stars and releases immense energy.
What conditions are required for nuclear fusion to occur?
Extremely high temperature, density, and long confinement times.
Similar to conditions found in star cores.
What is half-life?
The time it takes for half of a radioactive material to decay.
Predictable for large samples but unpredictable for individual atoms.
What is the formula for calculating remaining mass using half-life?
A = A₀(½)^(t/h)
Where A is remaining mass, A₀ is initial mass, t is time, and h is half-life.
What is carbon-14 used for?
Dating ancient organisms by measuring the decay to nitrogen-14.
Effective for dating up to about 60,000 years.
What is the half-life of cobalt-60?
5.27 years.
Example of a radioactive isotope with a known decay rate.
What happens to the binding energy as nucleons increase?
Initially increases rapidly, reaches a maximum at iron (56 nucleons), then decreases slowly.
Indicates stability changes in nuclei.
