Unit 2 – Atomic Structure & Nuclear Chemistry

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 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

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

assumes the same number for each object; the mean of an object

doesn’t have equal number of all the objects; multiply the atomic mass of each isotope, then add the results

multiply the mass with the percent abundance

can’t penetrate thin objects

written as α or 42He; has two protons and neutrons; also has a plus two charge

Requires a minimum of wood or aluminum foil to stop penetration. Formed by electrons, also known as beta particles.

lighter than alpha particles; has both positive and negative charge or one

electromagnetic radiation; low energy light rays; gamma rays

x-rays; electrons in certain metals lose energy

Involves the splitting of the nucleus of an atom. Occurs in nuclear bombs and nuclear power plants.

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

alpha radiation

gamma radiation