atomic number test
what is an ion ?
and atom or group of atoms that has an electric charge other than zero, created when an atom gains or loses electrons .
what is an isotope ?
atoms of the same element that have different numbers of nuetrons in the nucleus.
what is the atomic mass ?
average mass of all the known isotopes of an element .
what does the group number tell you about an element ?
elements with similar properties
what does the period number tell you about an element ?
elements with the same number of atomic or orbits .
what element group is highley inactive because they have a full set of valence electrons ?
noble gases
atoms of the same element can have different number of _____?
nuetrons
what is an orbit or energy level ?
one of the discrete allowed energies for electrons in an atom .
atoms of the same element have the same number of _______?
protons
what is the definition of an atom ?
smallest particle of an element that retains the chemical identity of an element.
what is the atomic number ?
the number of protons in the nucleus determines what element the atom represents .
what is the mass number ?
the number of protons plus the number of nuetrons in the nucleus .
what is the definition of a nucleus ?
tiny core at the center of an atom containing most of the atom's mass and all of its positive charge .
the nucleus has a charge of ______?
zero
the overall charge of an atom is ____ because the number of ______ equals the number of _____?
zero , protons , electrons .
what is the definition of a proton ?
A particle found in the nucleus with a positive charge exactly equal and opposite to the electron .
what is an element ?
A pure substance that cannot be broken down into simpler substances by physical or chemical means .
what is a compound ?
A substance that contains two or more different elements chemically joined and has the same composition throughout .
what is a molecule ?
a group of two or more atoms joined together by chemical bonds.
what is the definition of an electron ?
a particle with an electrical charge found inside of the Atomms but outside of the nucleus .
all of the elements in what group are radioactive ?
actinides
