Science chap 7 Flashcards
the smallest piece of an element that still represents an element
atom
a particle with one negative charge (-1)
electron
most of an atom’s mass and positive charge is concentrated in a small area in the center of an atom
nucleus
atomic particle that has one positive charge (1+)
proton
neutron
neutral particle that exists in the nucleus of an atom
area around an atomic nucleus where an electron is most likely to be located
electron cloud
number of protons in an atom of an element
atomic number
element is the avarage mass of the element isotopes, weighted according to the abundance at each isotope
average atomic mass
element that spontaneously emits radiation
radioactive
process that occurs when an unstable atomic nucleus changes into another more stable nucleus ny emitting radiation
nuclear decay
ion
an atom that is no longer neutral because it has gained or lost electron
Two neutral atoms that have the ame atomic number and different mass numbers are
isotopes
An ion that has a negative charge is formed when an atom
gains electron
The atomic theories of Dalton and Democritus included the idea that atoms
cannot be divided created or destroyed
Two atoms of different elements will definitely have different numbers of
protons
