Year 8 Physics - Energy and Radiation

Flashcards for review of energy, radiation, atomic structure, and nuclear processes.

What is energy?

The ability to do work.

Name two broad categories of energy.

Potential Energy and Moving Energy.

Give examples of Potential Energy.

Gravitational, Chemical, Nuclear, Elastic, and Electrical Potential Energy.

Give examples of Moving Energy.

Kinetic, Sound, Light, Heat or Thermal Energy.

What does the Law of Conservation of Energy state?

Energy can only be transformed or transferred, but not created or destroyed (except in a nuclear reaction).

Define radiation.

The transfer of energy via particles or waves.

What are the two types of waves regarding radiation?

Mechanical and electromagnetic.

What do mechanical waves require to propagate?

A medium (matter).

Give examples of mechanical waves.

Sound waves, water waves, and earthquake waves.

What are the two types of mechanical waves?

Transverse and longitudinal.

What do electromagnetic waves travel through?

Light and do not require a medium.

Give examples of electromagnetic waves.

Visible light, microwaves, and radio waves.

How does wavelength affect the energy of an electromagnetic wave?

As the wavelength increases, the energy decreases.

List the types of EM waves in order of decreasing wavelength (increasing energy), beginning by radio waves.

Radio, Microwave, Infrared, Visible, Ultraviolet, X-ray, Gamma ray.

What are atoms made of?

Subatomic particles: protons, neutrons, and electrons.

Define atomic number.

The number of protons in the nucleus of an atom of an element.

Define mass number.

The total number of protons and neutrons in the nucleus of an atom.

Define isotopes.

Atoms with the same number of protons, but a different number of neutrons.

Define ion.

A particle with an unequal number of protons and electrons.

How is an ion formed?

When an atom loses or gains an electron.

What is ionization?

When an atom loses an electron and its overall charge changes from neutral to positive.

Define ionizing radiation.

Radiation with high enough energy to remove an electron from its atom.

Give examples of ionizing radiation.

Gamma rays, X-rays, high-energy ultraviolet (UV-C), and all types of nuclear radiation.

What is nuclear radiation?

Radiation that is emitted from the nucleus of an atom.

Name three types of nuclear radiation.

Alpha particles, beta particles, and gamma waves.

What force holds the nucleus of an atom together?

The strong nuclear force.

Describe alpha particles.

Made from two protons and two neutrons, with a relative mass of 4 and a charge of +2.

Describe beta particles.

Electrons with very high energy; relative mass of 1/2000 and a relative charge of -1.

Describe gamma rays.

Very high-energy electromagnetic waves with no mass and no charge.

What is the penetration ability of alpha particles?

Low; can be blocked by a thin piece of paper or skin.

What is the penetration ability of beta particles?

Medium; can pass through paper and skin but blocked by thin metal.

What is the penetration ability of gamma rays?

High; can easily pass through thin materials; blocked by thick, dense materials like lead.

What is radioactive decay?

The process by which an unstable parent nucleus transmutes into a daughter nucleus by emitting nuclear radiation.

Describe alpha decay.

Two protons and two neutrons break off the unstable parent nucleus to form the alpha particle. mass number decreases by four. Atomic number decreases by two

Describe beta decay.

One neutron in the unstable parent nucleus transmutes into one proton daughter nucleus . Mass number stays the same. Atomic number increases by one

Describe gamma decay.

The neutrons and protons in the nucleus rearrange into a more stable configuration Daughter nucleus is the same element and isotope as parent nucleus.