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Chemistry (Chapter 4)

Chapter 4 vocab and important notes
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Tiny particles that compose elements
atoms
Atoms of any one element _____from those of another element
differ
Atoms of different elements can form __________ by combining in whole-number ratios
compounds
Chemical reactions occurs when atos are ________
separated, joined, or rearranged
T or F: Atoms of one element change into atoms of another element during chemical reactions
False
T or F: Atoms of one element are different from atoms of another element
True
The smallest particle of an element that retains its identity in chemical reactions
atom
an instrument used to generate images of individual atoms
scanning tunneling microscope
English chemist and schoolteacher who formulated a theory to describe the structure and chemical reactivity of matter in terms of Atoms
John Dalton
Greek philosopher who was among the first to suggest the existence of atoms
Democritus
In what type of ratios do atoms combine to form compounds
whole number ratios
What did Dalton discover that changes the theory about atoms being indivisible
subatomic particles
What kind of charge do electrons have?
negative
What has a positive charge?
protons
Which has a neutral charge?
neutrons
Which are found in the nucleus of the atom?
protons and neutrons
Who discovered the nucleus of the atom?
Ernest Rutherford
What kind of charge does the nucleus have?
positive
What occupies most of the volume of the atom?
electrons
T or F: According to Dalton's atomic theory, toms are composed of protons, electrons, and neutrons
False
T or F: Atoms of elements are electrically neutral
True
T or F: The mass of an electron is equal to the mass of a neutron
False
T or F: The charge on all protons is the same
True
negatively charged subatomic particles
electrons
a stream os electrons produced at the negative electrode of a tube containing a gas at low pressure
cathode ray
positively charged subatomic particles
protons
subatmic particles with no charge
neutrons
the central core of an atom, which is composed of protons and neutrons
nucleus
Which subatomic particles are charged
electrons and protons
The number of ______ in the nucleus of an atom is the atomic ______ of that element
protons, number
Because atoms are electrically neutral, the number of protons and _____ are the same
electrons
The total number of ____ and neutrons in an atom is the _______
protons, mass number
Atoms of the same element are identical in most respects, but they can differ in the number of ________ in the nucleus
neutrons
Atoms that have the same number of protons but different mass numbers are called?
isotopes
The _____ of an element is the weighted average of the masses of the isotopes of that element
atomic mass
Each of the three known isotopes of hydrogen has ___ proton in the nucleus 1
one
The most common hydrogen isotope has ___ neutrons
no
It has a mass number of ____ and is called hydrogen-1
one
T or F: The atomic number of an element is the sum of the protons and electrons in an atom of that element
False
T or F: The atomic number of an atom is the total number of protons in an atom of that element
True
T or F: Relative atomic masses are expressed in AMUs
True
T or F: The number of neutrons in the nucleus can be calculated by subtracting the atomic number from the mass number
True
the number of protons in the nucleus of an atom of an element
atomic number
an arrangement of elements according to similarities in their properties
periodic table
equals the number of neutrons plus the number of protons in an atom
mass number
the vertical column of elements in the periodic table
group
atoms that have the same number of protons but different numbers of neutrons
isotopes
1/12 the mass of a carbon-12 atom
atomic mass unit
weighed average mass of atoms in a naturally occurring sample of an element
atomic mass
a horizontal row of the periodic table `
period
Who found the electron?
J.J. Thompson
Who found protons?
Eugene Goldstein
Who found the neutron?
James Chadwick