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Test 2

Terms in this set (30)

proton
found in tue nucleus, has a positive electrical charge, amu 1
neutron
found in the nucleus, neutral, no charge, amu 1 slightly larger that proton
electron
found in the nucleus orbitals, negative charge, little or no mass amu 1/1836
atomic number
the number of protons found in the nucleus if an atom, and identifies it as a particular element
number of protons
number of electrons
mass number
the number of protons and neutrons found in the nucleus of an atom
Mass number - atomic number =
number of neutrons
isotopes
atoms that have the same number (protons) but different mass numbers (neutrons)
same chemical properties but different physical properties
isotopes MUST
MUST be the same element
most abundant isotopes
closest to average atomic mass on periodic table
orbitals
described as a region in which an electron of a particular amount of energy can be located
atomic mass
weighted average of all naturally occurring isotopes
Dalton
all elements are composed of indivisible atoms, which are the smallest particles of mass
All atoms of an element are exactly the same
JJ Thomson
plum pudding model
Discovered the electron
Used cathode ray tube it show one of the smaller units that make up an atom
He discovered the electron
Ernest Rutherford
good foil experiment
He proved that an atom is mainly empty space
Dense center containing most of the atoms mass, nucleus
Nucleus has a positive charge
(modern atomic theory)
Bohr model
proposed a model of the atom showing a dense nucleus with electrons found in the surrounding orbitals
(modern atomic theory)
Wave mechanical model
proposed the atom as having a dense positively charged center(nucleus)
Electrons have a definite amount if energy and they are moving orbitals
Compared to the charge of a proton, the charge of an electron has
the same magnitude and the opposite sign
Which particle has no charge
neutron
What is the approximate mass of a proton
1u
Which particles have approximately the same mass?
a neutron and proton
An atom of lithium- 7 has an equal number of
electrons and protons
Which phrase describes an atom?
a positively charged nucleus surrounded by negatively charged electrons
A neutron has a charge of
0
In the late 1800s, experiments using cathode ray tubes led to the discovery of the
electron
Which part of a helium atom is positively charged
nucleus
Which statement describes the distribution of charge in an atom
a positively charged nucleus is surrounded by one or more negatively charged electrons
As a result of the gold foil experiment, it was concluded that an atom
contains a small dense nucleus
What was concluded about the structure of the atom as the result of the gold foil experiment?
A positively charged nucleus is surrounded by mostly empty space
Which statement about one atom of an element identifies the element?
The atom has 1 proton
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