Structure of Matter Flashcard

Alpha Particle
Particle radiating from the nucleus of some atoms. Identical to a helium nucleus.
atom
The smallest particle of matter still retaining the characteristics of the element; building block of matter.
atomic weight
The total number of protons plus neutrons in an atomic nucleus.
atomic number
The number of protons in an atom; the number which identifies an element.
beta particle
Negative particle identical to an electron but radiating from a decaying nucleus; it is symbolized by e.
chain reaction
A spontaneous or induced reaction that continues to feed itself and keep itself going.
critical mass
Mass of a nuclear substance that, if combined into one piece, would result in a spontaneous nuclear reaction.
curie
A unit of radiation equaling 3.7 x 1010 disintegrations per second.
electron
Tiny negatively charged particle circling the nucleus. 1/2,000 the mass of a proton or neutron; it is symbolized by e, or β.
element
Matter made up of just one type of atom.
fission
Nuclear reaction producing lighter elements and energy by splitting.
fusion
Nuclear reaction producing heavier elements and energy by synthesis.
gamma ray
High-intensity bundle of energy being emitted from some decaying nuclei; it is symbolized by γ.
isotope
Atom with the standard atomic number and chemical properties but different atomic weight and physical properties.
meson
A particle one-eighth the mass of protons; charge varies. Symbolized by K,μ, or Π.
neutrino
Neutral particle of nearly zero mass, produced by decaying nuclei and symbolized by ν.
neutron
Neutrally charged particle in the nucleus of an atom. Has the same mass as the proton; it is symbolized by η.
nucleus
The center of the atom made up of protons and neutrons.
positron
Nuclear particle of the mass of an electron but with a positive charge.
proton
Positively charged particle in the nucleus of an atom; symbolized by ρ.
roentgen
Amount of radiation needed to produce 1.6 x 1012 positive or negative particles due to gamma rays passing through one gram of air.
synthesis
Combining, assembly of components.

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