Atomic Structures Vocabulary (unit 1)

Atomic Structure & Electromagnetic Radiation

Angstrom Å

subatomic unit of distance equal to 10^-10 meters, used to measure wavelength

Matter

has form or shape and occupies space

Mass

quantity of matter contained in object

units: kilogram or grams

Weight

force that object exerts under influence of gravity

Substance

a material with a definite and constant composition

Element

a simple substance which cannot be broken down into any simpler substance by ordinary means

Compound

a complex substance made of two or more elements that are chemically united in definite proportions

Molecule

when 2 or more atoms chemically unite

smallest unit of chemical compound

Atom

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

Atomic #

Z-number - determined by the number of protons in an atom which is unique to each element

Proton

positively charged particle found in the nucleus of an atom - determines the atomic number

Neutron

subatomic particle found in the nucleus of an atom - has no charge & is considered neutral

Nucleon

Nuclear particle - includes protons and neutrals

Atomic Mass (A)

total number of nucleons (protons + neutrons) in an atom

amount of matter in an object - generally considered the same as weight for rad. purpose

Electron

negatively charged subatomic particle that orbits the nucleus and has essentially no weight

Covalent Bond

occurs when two atoms share their unpaired electrons - the most common form of Bonding (forms a weak bond)

Ionic Bond

atoms with opposite charges are attracted - this force pulls them together to form a strong bond

Ionization

the process of adding or removing an electron from an atom

Periodic Table

a table of elements listed in order of their atomic or Z number, with elements in the same columns having similar chemical properties

Radiation

energy that is emitted and transferred through space

Isotope

atoms of an element that have the same number of protons but a different number of neutrons

makes atom unstable which results in radioactivity

atom gains or loses neutrons

Radionuclide

any atom which is radioactive (unstable)

Radioisotope

any atom which is radioactive because it has too few or too many neutrons

Radioactive Decay

the loss of any mass or energy from the nucleus of an atom

AMU

atomic mass units - mass of particles of an atom

Electron Binding Energy

the amount of energy needed to remove the electron from the atom

Frequency

the number of waves passing a particular point in a given time

Photon

a small bundle of energy - amount of energy depends on the frequency

Valence

the number and configuration of the electrons in the outer shell

Octet Rule

the number of electrons in the outer shell of an atom never exceeds 8 electrons

K Shell

the orbital shell closest to the nucleus

Dual Nature of X-rays

X-rays travel in waves but behave as a particle when interacting with matter

Speed of light

186,000 miles/sec in a vacuum OR 3×10⁸ meters/sec in a vacuum

Wavelength of X-rays

0.1 to 0.5 Å

Energy

the ability to do work

Kinetic Energy

energy of motion

Potential Energy

energy of position (stored energy until converted)

Chemical Energy

energy resulting from a chemical reaction

Electrical Energy

energy that is emitted and transferred thru matter

Thermal Energy

energy resulting from movement of atoms of molecules

Nuclear Energy

energy resulting from the nucleus of an atom

Electromagnetic Energy

energy that is emitted and transferred thru matter

radio waves, microwaves, infrared, visible, ultraviolet, X-ray, gamma rays