Ch. 2/3- Radiation Concepts and Electricity

Matter

has mass and occupies space

Energy

force used to do work, unit J

radiation

emitted energy that is transmitted through matter. All radiation has a magnetic field. There is man made and natural radiation

exposed/irradiated

when any form of matter is struck by a form of radiant energy

Law of conservation of matter and energy

E=mc². The sum of all matter and energy is constant. It cannot be created or destroyed but they can be converted from one form to another

simple substance

element or pure substance. Can’t be broken down

complex substance

compound, 2 or more different elements are chemically united. Visible, ex. H2O

atom

smallest particle of an element that still possesses the chemical properties of that element.

divided into 3 basic subatomic particles

-protons

-neutrons

-electrons

molecule

2 or more atoms are chemically united. Smallest particle of a compound

mixtures

two or more substances combined

states

solid, liquid, and gas. depends on varying degrees of molecular attraction, depends on temperature

nucleus

small, dense centre

contains nucleons (protons and neutrons)

electrons

orbit nucleus in a variety of planes

in specific energy states

quantum

“a small bundle of energy”

quantum physics

the study of matter and energy at its most fundamental level

-electrons cannot be divided

-protons and neutrons made up of “quarks”

M theory (string theory)

links quantum physics and relativity (E=mc²)

How matter responds to stimuli and environmental factors on quantum level

pictured particles as quickly moving strings

proton

positive charge

Mass number of 2

neutron

neutral charge, mass number of 1

electron

negative charge, very small mass, negligible

If you change the Z# (atomic#)

change number of protons, change the element

change number of neutrons

isotopes, only changes the mass

change number of electrons

ions/ionization, only changes charge

ionization

addition/removal of electrons from an atom

X-ray photons can interact with an atom, results in ejection of electron

changed charges between atoms

created by energy and interacting with matter

atomic mass

concentrated in nucleus. Atomic mass # consists of total protons and neutrons

orbital

curved path an object follows in space around another object due to gravity

defines location where an electron might be at any given time in atom

shells

K, L, M, N, O, P, Q

or n=1, 2, 3, 4, 5, 6, 7

stronger bond closer to nucleus

electron capacity=

2n² (n=orbital shell #)

Electron Binding Energy (Eb)

energy needed to eject electron from atom

• related to how close an electron is to nucleus (higher Eb closer to nucleus)

• Eb increases as Z# increases

Binding energy results from positive attraction of nucleus to electron

Valence

stability of outermost shell

octet rule

want 8 electrons on valence shell

work

work= force x distance

force acting upon object over distance expends energy and is considered work (w)

mechanical energy

action of physical movement (potential and kinetic)

potential energy

energy because of position, at rest

kinetic energy

energy of motion

chemical energy

energy released from chemical reaction

heat energy (thermal energy)

results from movement of molecules. The faster they move (more heat), higher energy

temperature measures thermal energy

nuclear energy

obtained by breaking bonds between particles (nucleons) within nucleus. takes a lot of energy to break that nucleus

electricity

the study of resting or moving electrical charges

occurs within the conduction band (or orbitals) of an atom

electrical energy

results from movement of electrons in conductor

electromagnetic (EM) energy

combination of electric and magnetic fields travelling through space. (any time you have an electric current, you have a magnetic field)

produced by the acceleration of a charged particle

illustrated as a wave-like energy disturbance traveling through space

can travel through medium or vacuum

results in excitation/ionization (addition/removal of electron)

EM energies arranged in a spectrum according to wavelength and frequency

X-ray is one type of EM energy

Characteristics of EM radiation

wavelength, energy, frequency

wavelength

distance between the peaks of 2 waves, measured in A

energy

measured in J

frequency

cycles per second, measured in Hz

how are wavelength and frequency related

inverse relationship

particle theory

X-rays act more like particles than waves

high frequency, high energy EM radiation

bundles of energy (photons or quantum)

how are photon energy and frequency related

directly related

discovery of X-rays

Nov 8, 1895 by Wilhelm Conrad Röntgen. Occurred while studying behaviour of electrons traveling through gas tube

X-ray properties

-penetrating and invisible form of EM radiation

-electrically neutral

-polyenergetic or heterogeneous energies

-release heat when passing through matter

-travel in straight lines

-travel at the speed of light

-can ionize matter

-cause fluorescence (the emission of light) of certain crystals

-cannot be focused by a lens

-affect photographic film

-produce chemical and biological changes in matter through ionization and excitation

-produce secondary and scatter radiation