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Atomic Theory

Scientists and Atomic models

Atom The smallest unit of an element that maintains (keeps) the properties of that element.
Electron A negatively charged subatomic particle OUTSIDE the nucleus of an atom.
Nucleus In physical science, an atom's central region.
Proton A subatomic particle that has a POSITIVE charge and that is located INSIDE the nucleus.
Neutron A subatomic particle that has a NO CHARGE and that is located INSIDE the nucleus.
Electron Cloud An area around the nucleus where electrons are in motion.
Atomic Number The number of protons (and electrons) in an atom. The atomic number is the same for all atoms of that element.
Mass Number (Atomic Mass) The sum of the numbers of protons and neutrons in the nucleus of an atom.
Isotope One of 2 or more atoms that have the same number of protons (atomic number) but different numbers of neutrons (atomic mass)
JJ Thomson Individual atoms were thought of as positively charged SPHERES with negatively charged electrons EMBEDDED (stuck) in it. Plum Pudding
Niels Bohr Explained that electrons were moving in FIXED SHELLS around the nucleus.
John Dalton British school teacher that proposed the first atomic theory.
Ernest Rutherford Individual atoms were positively charged spheres with negative electrons ORBITING the center. The atom is MOSTLY EMPTY SPACE.
Modern Model The atom has a positively charged nucleus and a negatively charged CLOUD of electrons.
Created by: llembke