Unit Three: Atoms, Moles, and Nuclear Chemistry

occurs when one atom’s nucleus splits
apart

the smallest component of an element, consisting of a nucleus containing neutrons and protons and one or more electrons

the number of protons in the nucleus of a given element

average mass per atom of an element

particle that is a fundamental constituent of matter, having a negative charge

two or more forms of an element, having the same number of protons, but having different numbers of neutrons

the integer nearest in value to the atomic weight of an atom

within an atom, containing protons and neutrons

a neutrally charged particle of matter, found in nucleus

a positively charged particle of matter, found in nucleus

a unit of mass used to express atomic and molecular weights

the mass in grams of 1 mole of a substance

a unit of counting, one mole = 6.02 x 10^23 particles, atoms, ect.

-Made of 2 protons and 2 neutrons
-+2 charge
-Helium nucleus
-Stopped by paper
-2nd leading cause of lung cancer
-Used in smoke

-High speed electron
-Charge of -1
-No mass
-Stopped by plastic, thin sheet of metal, or wood
-Used in PET scans

-Most penetrating and dangerous form of
radiation
-Can damage human skin, DNA and
organs
-Some can be stopped by lead or concrete
-Used to kill cancerous cells
-Pure energy

the time required for one-half of a radioisotope’s nuclei to decay into its products

when an element has an unstable isotope, it becomes radioactive

occurs when two or more atoms nuclei come together to form one atom

change of an atom of one element to another element through nuclear reactions