Unit 2 – Atomic Structure & Nuclear Chemistry

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Atomic Number
Equals the number of protons in the nucleus; number on top of an element symbol.

Will also equal the number of electrons in a neutral atom.

Mass Number
Mass = number of protons + neutrons

The bottom number on the periodic table

Has no charge (electrically neutral). Found by subtracting the atomic number from the atomic mass.
Have a positive charge; upper left number of an element symbol.
Have a negative charge; the number of electrons will be the same number as the protons for a neutral atom.
Isotopes of the same element have the same number of protons but has different numbers of neutrons resulting in a different atomic mass.

Example: oxygen-15 and oxygen-16 are isotopes of each other

Complete Symbol
the symbol of the element; includes mass number and atomic number
good conductors; high luster(shiny); malleable(breakable)
mostly gases; brittle; poor conductors
similar to metals and nonmetals
Simple Average
assumes the same number for each object; the mean of an object
Weighted Average
doesn’t have equal number of all the objects; multiply the atomic mass of each isotope, then add the results
Average Atomic Mass
multiply the mass with the percent abundance
Alpha Radiation
can’t penetrate thin objects
Alpha Particle
written as α or 42He; has two protons and neutrons; also has a plus two charge
Beta Radiation
Requires a minimum of wood or aluminum foil to stop penetration. Formed by electrons, also known as beta particles.
Beta Particle
lighter than alpha particles; has both positive and negative charge or one
Gamma Radiation
electromagnetic radiation; low energy light rays; gamma rays
x-rays; electrons in certain metals lose energy
Nuclear Fission
Nuclear Fission
Involves the splitting of the nucleus of an atom. Occurs in nuclear bombs and nuclear power plants.
Nuclear Fusion
Nuclear Fusion
Combines small nuclei and fuses them into a larger nucleus. Releases more energy than fission. Occurs in the Sun and other stars
time for half of the atoms to produce radiation and decay to products
Which of the following will penetrate the least: alpha, beta, gamma?
alpha radiation
Which of the following will penetrate the furthest: alpha, beta, gamma?
gamma radiation
Categories: Nuclear Chemistry