GHSGT Science Review

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GHSGT Science Review

• Domain 4 Energy Transformations
• Ppt 1

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Pre-review Questions

• 1. What is radioactivity?
• 2. What is a half-life?
• 3. What are the 3 major phases of matter?
• 4. Compare the relative motion of particles
  between the different phases of matter.
• 5. Does a phase change require the gain or loss
  of energy?
• 6. What is thermal energy?
• 7. Describe conduction, convection, and radiation.

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Radioactivity

• Radioactivity is what results from the
  spontaneous breakdown of a radioactive isotopes
  unstable atomic nucleus.
• Types of radioactive decay
• Alpha particles composed of 2 neutrons and 2
  protons.
• Beta electron emission
• Gamma Not a particle electromagnetic radiation.

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Half-lives

• The amount of time it takes for half of the
  original sample of the radioactive isotope to
  break down.
• Ex The half-life of I-125 is 60.14 days. If you
  have 100 g of I-125 60.14 days later you would
  only have 50 grams of this radioactive isotope
  remaining. Another 60.14 days later there would
  be 25 g.and so on

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Phases of Matter

• Solid Definite shape and volume Particles
  closely packed together with low energy and very
  little particle movement compared to the other
  phases.
• Liquid Indefinite shape but a definite volume
  Particles have more energy and movement than
  those in a solid, but less than those in a gas.

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Phases of Matter cont.

• Gas Indefinite shape and volume. (It fills its
  container and takes its shape). Particles have
  more energy and move more in gases than in
  liquids or solids.

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Phase Changes

• Phase changes require the loss or gain of energy.
  
• If you are going from a phase of higher energy to
  lower energy (Ex freezing, condensation) then
  energy will be released.
• If you are going from a phase of matter that is
  lower in energy to one that is higher energy (Ex
  melting, vaporization) energy is required to be
  added.

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Thermal Energy vs Heat

• Thermal energy is defined as the total energy of
  molecular motion in a substance, and when this
  energy is transferred, it is called heat

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Methods of Thermal Energy Transfer 1

• 1. Conduction
• is the transfer of thermal energy between
  neighboring molecules in a substance due to a
  temperature gradient.
• It always takes place from a region of higher
  temperature to a region of lower temperature, and
  acts to equalize temperature differences.
• Conduction takes place in all forms of matter
  solids, liquids, and gases, but does not require
  any bulk motion of matter

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Conduction
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Methods of Thermal Energy Transfer 2

• 2. Convection
• is the movement of molecules within fluids
  (liquids gases). It cannot take place in
  solids, since neither bulk current flows or
  significant diffusion can take place in solids.
• in which matter or thermal energy is transported
  by the larger-scale motion of currents in the
  fluid.

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Convection
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Methods of Thermal Energy Transfer 3

• 3. Radiation
• Radiation is the transfer of thermal energy
  through empty space from electromagnetic waves.
  (Ex the energy from the sun)

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Radiation