Chapter 8

proton

a positively charged subatomic particle found in the nucleus of every atom

neutron

a subatomic particle that has no electric charge, found inside the nucleus of every atom

electron

a stable, negatively charged subatomic particle with very little mass, found orbiting the nucleus of an atom

nucleus

the central core of an atom

Radioactive isotope

An isotope that is unstable and eventually decays to become a different atom

Beta Decay

Radioactive decay in which a neutron emits an electron to become a proton

Electron Capture

Radioactive decay in which a proton absorbs an electron to become a neutron

Alpha decay

Radioactive decay in which a nucleus ejects two protons and two neutrons as a single particle

Half-life

The time it takes for half a sample of radioactive atoms to decay

radiometric dating

The process by which radioactive decay is used to determine the age of a specimen

bracketing

the process of dating a layer of sedimentary rock based on the layers above and below it

hydrothermal vent

an opening in the seafloor that emits hot, mineral-rich water

Great Unconformity

an obvious separation between the igneous and metamorphic rocks near the bottom of the bottom of the formation and the sedimentary rock near the top

runaway subduction

a theoretical catastrophic geological process where cold, dense oceanic plates rapidly sink deep into the Earth's mantle, accelerating as heat weakens surrounding rock, creating immense energy

geyser

a vent in the earth’s surface that ejects a column of hot water and steam