Name ______Period ____

Energy Unit Study Guide

  1. Describe the relationship between wavelength, frequency, and energy.
  • As energy increases frequency increases, as energy decreases frequency decreases. (directly proportional relationship)
  • As energy/frequency increases wavelength decreases, as energy/frequency decreases wavelength increases. (inversely proportional relationship)
  1. Calculate the following problems.

C = λνE = hν

C = 3.00 x 108 m/sh = 6.626x 10-34 J-s (or J/Hz)

  1. What is the wavelength of a wave having a frequency of 3.76 x 1014 s-1?

(3.0x108)/(3.76x1014) =7.98x10-7 m

  1. What is the frequency of a 6.9 x 10-13 m wave?

(3.0x108)/(6.9x10-13) =4.35x1020 Hz

  1. What is the wavelength of a 2.99 Hz wave?

(3.0x108)/(2.99) =1.00x108 m

  1. What is the frequency of a 7.43 x 10-5 m wave?

(3.0x108)/(7.43x10-5) =4.04x1012 Hz

  1. What is the energy of a 7.66 x 1014 Hz wave?

(7.66x1014)(6.626 x 10-34)= 5.08x10-19 J

  1. What is the frequency of a wave carrying 8.35 x 10-18 J of energy?

(8.35x10-18)/(6.626 x 10-34)= 1.26x1016 Hz

  1. What is the frequency of a 1.78 x 10-15 J wave?

(1.78x10-15)/(6.626 x 10-34)= 2.69x1018 Hz

  1. What is the energy of a 3.12 x 1018 s-1 wave

(3.12x1018)(6.626 x 10-34)= 2.07x10-15 J

  1. What is electromagnetic radiation?
  • Energy that moves through space and matter both in the form of magnetic and electric waves and in the form of a stream of particles.
  1. Describe the different types of electromagnetic radiation found on the electromagnetic spectrum.
  • Radio waves Lowest frequency and energy, longest wavelength, used by radio stations and televisions.
  • Microwaves Used in communications and cooking. Used in Cell phones.
  • Infrared Heat you feel from a fire or electric heater. Ex. –Fry warmer
  • Visible Light Only part of the electromagnetic spectrum that we can see with the naked eye. ROY G. BIV
  • Ultraviolet The part of the sunlight that caused sunburns. Used in tanning beds
  • X-rays Type of radiation that passes through soft tissue but is stopped by bone. Allows for a picture of a bone to be taken (x-ray)
  • Gamma Ray Highest energy and frequency, shortest wavelength, Used in cancer treatment.
  1. Why have the theories about the shape and structure of an atom changed? Why do they continue to change?
  • They have changed as scientists have made more discoveries about the atom. They continue to change because technology has allowed us to learn so much more about the atom.
  1. How are the colors of the continuous spectrum related to wavelength and energy?
  • The colors are arranged according to the wavelength and energy that is associated with them. Red has the lowest amount of energy and the longest wavelength. Violet has the highest amount of energy and the shortest wavelength. The colors in between are arranged according to energy and wavelength. Red, Orange, Yellow, Green, Blue, Indigo, Violet
  1. How are photons of light directly related to the amount of energy absorbed by an atom?
  • The color that is emitted is directly proportional to the amount of energy that is absorbed by the atom. Red =lower amount of energy Violet=higher amounts of energy
  1. How can the spectra of an unknown gas be used to identify the element?
  • By looking at the spectra of known gases we are able determine the type of gas. Each element has its unique spectra that can be compared to the spectra of the unknown gas. If the spectra match, you can know the type of gas.
  1. How can scientist use spectral analysis to identify the elements found in those stars?
  • They can use the spectra of the star and compare it to the spectra of the known elements on Earth. If the known spectra match the stars spectra, then that element is found in the star.
  1. Identify which of the elements listed below are found in Star A and which elements are found in Star B.

Star A= Sodium, Hydrogen and Helium

Star B= Mercury, Hydrogen, and Helium

  1. Know how to write the electron configurations and orbital diagrams of different elements. Complete the following worksheet.

Orbital Diagram / Electron Configuration / Noble-gas Notation
Be / / 1s22s2 / [He]2s2
O / / 1s22s22p4 / [He]2s22p4
P / / 1s22s22p63s23p3 / [Ne]3s23p3
Fe / / / [Ar]4s23d6
  1. What types of atoms are more likely to go through radioactive decay?

`Unstable nuclei. Elements that have a large number of neutrons.

  1. Describe the types of radioactive particles.

Alpha Particles consist of two protons and two neutrons, and are emitted during some kinds of radioactive decay. Helium nuclei.

A Beta particle is an electron created and emitted when a neutron is transformed* into a proton and an electron during radioactive decay.

Gamma rays are photons of electromagnetic radiation with high frequency and energy. Gamma rays are given off when the nucleons undergo an abrupt energy difference. Gamma rays have no mass – they are pure energy.

A positron is a particle that has the same mass as that of an electron, but has a positive charge.

  1. What is alpha decay?

Alpha decay is the radioactive decay of an unstable nuclei that the atomic number is reduced by two and the mass number is reduced by four as an alpha particle is produced. Alpha rays are relatively slow and easy to stop – a piece of paper will stop alpha particles.

  1. What is beta decay?

Beta decay is the radioactive decay of an unstable nuclei that the atomic number is increased by one and the mass number stays the same asabeta particle is produced. Essentially a proton becomes a neutron. Beta rays travel faster than alpha rays and can penetrate paper, but are generally stopped by thin sheets of metal such as aluminum.

  1. What is gamma ray production?

Because they have no charge and are high energy, gamma rays travel far and penetrate further than alpha or beta rays. Thick concrete or lead is needed to stop gamma rays. The release of gamma rays alone do not affect the identity of the atom since they have no mass and no charge. But, gamma radiation may be released along with release of an alpha or beta particle.

  1. Complete the following decay problem.

  1. What is half-life? The time required for half of the original sample of nuclei to decay.
  1. What is the difference between physical change, chemical reactions, and nuclear reactions?

During a physical change the chemical composition remains the same. This can be easily reversible.

Chemical reactions are a change in the chemical composition – a rearrangement of the atoms in the compounds. The atoms involved will remain the same.

Nuclear reactions is when the nucleus of an atom is changed. This will change the identity of the atoms involved.

  1. Determine the half-life of the element using the graph below.

The half-life is 2 days.

  1. Describe the penetrating power of alpha, beta, and gamma radiation.

Alpha is easily stopped by paper.

Beta is stopped by metal foils.

Gamma is stopped by thick concrete and lead.

  1. Compare the energy released between a chemical reaction and a nuclear reaction.

The energy released during a nuclear reaction is millions of times greater than during a chemical reaction.

  1. Describe Fusion? Where does it commonly occur?

Fusion is the combining of nuclei. This occurs on the sun as helium nuclei are combined to from heavier elements.

  1. Describe fission? Where does it commonly occur?

Fission is the splitting of a nuclei. This is what is used in an atomic bomb and nuclear power plants.

  1. Which of the following is easily reversible?

Physical change, chemical change, nuclear fission, or nuclear fusion

  1. Describe nuclear energy.

Nuclear energy is a controlled nuclear reaction where atoms are split resulting in the release of energy that heats water to steam that will then turn a turbine that will create electricity.

  1. What are the advantages and disadvantages of nuclear energy?

Advantages

  • Nuclear power costs about the same as coal, so it’s not expensive to make.
  • Does not produce smoke or carbon dioxide.
  • Produces huge amounts of energy from small amounts of fuel.
  • Produces small amounts of waste
  • It is reliable

Disadvantages

  • The waste is very dangerous
  • Takes years for the waste to become safe
  • Safety requirements are expensive.
  • Nuclear disasters can be a major disaster to the environment and the population.