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15 terms

Chapter 4

Vocab
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Atom
the smallest particle of an element that retains it identity in a chemical reaction
Atomic mass
a weighted average mass of the atoms in a naturally occurring sample of the element
Atomic mass unit
one twelfth of the mass of a carbon-12 atom
Atomic number
the number of protons in the nucleus of an atom of that element
Cathode ray
a stream of electrons produced at the negative electrode of a tube containing a gas at low pressure
Dalton's atomic theory
the first theory to relate chemical changes to events at the atomic level
Electron
a negatively charged subatomic particle
Group
a vertical column of elements in the periodic table
Isotopes
atoms of the same element that have the same atomic number but different atomic masses due to different number of neutrons
Mass number
the total number of protons and neutrons in the nucleus of an atom
Neutron
a subatomic particle with no charge and a mass of 1 amu; found in the nucleus of an atom
Nucleus
the tiny, dense central portion of an atom, composed of protons and neutrons
Period
a horizontal row of elements in the periodic table
Periodic table
an arrangement of elements in which the elements are separated into groups based on a set of repeating properties
Proton
a positively charged subatomic particle found in the nucleus of atom