Chapter 4
If an atom of an element has a mass number of 32 and 20 neutrons in its nucleus, what is the atomic number of the element?
12
If an atom of tin has a mass number of 118 and an atomic number of 50, how many neutrons are in its nucleus?
68
If an atom has 34 protons and 40 neutrons, what is its mass number?
74
Which statement about subatomic particles is true?
An electron has far less mass than either a proton or neutron
Which statement about electrons and atomic orbitals is NOT true?
An electron has the same amount of energy in all orbitals.
According to _______________, all matter was made up of four elements ----- earth, air, fire, and water.
Aristotle
Which of the following is NOT part of John Dalton's atomic theory?
Atoms contain subatomic particles
Why is Bohr's model of the atom often called the planetary model?
Electrons orbit the nucleus like planets orbit the sun.
Which statement accurately represents the arrangement of electrons in Bohr's atomic model?
Electrons travel around the nucleus in fixed energy levels with energies that vary from level to level.
Who provided evidence for the existence of a nucleus in an atom?
Ernest Rutherford
Most calcium atoms have an atomic number of 20 and a mass number of 40, but some calcium atoms have a mass number of 48. What word could you use to describe these two kinds of calcium atoms?
Isotopes
Which statement best describes Rutherford's model of the atom?
It is like a hug stadium with a positively charged marble at the center
Which statement about subatomic particles is NOT true?
Protons and neutrons have the same charge
What did Democritus believe about matter?
That extremely small particles could not be divided.
What does the electron cloud model describe?
The number of electrons in an atom
Which of the following is unique for any given element?
The number of protons
Rutherford's gold foil experiment provided evidence for which of the following statements?
There is a dense, positively charged mass in the center of an atom.
Which of the following most accurately represents John Dalton's model of the atom?
a tiny, solid sphere with an unpredictable mass for a given element
The Greek philosopher Democritus coined what word for a tiny piece of matter that cannot be divided?
atom
The number of protons in one atom of an element is that element's
atomic number
Unlike Democritus, Aristotle did not believe that matter was composed of tiny, indivisible ____________.
atoms
The moving blades of an airplane propeller provide an analogy for the electron ______________ model.
cloud
John Dalton observed that elements always combine in the same ratio to form a particular ______________.
compound
In an atomic model that includes a nucleus, positive charge is...
concentrated in the center of an atom.
J.J. Thomson's experiments provided evidence that an atom
contains negatively charged particles
Which subatomic particle has a negative charge?
electron
In Bohr's model of the atom, _________________ move in fixed orbitals around the nucleus.
electrons
When an atom gains or loses energy, some of its _________________ may move between energy levels.
electrons
Which of the three subatomic particles - proton, electron, or neutron - has the least mass?
electrons
John Dalton concluded that all the atoms of a single ___________ have the same mass.
element
In Niels Bohr's model of the atom electrons move
like planets orbiting the sun
The _________ of an isotope is the sum of the number of protons and neutrons in its nucleus.
mass
To find the number of neutrons in an atom, you would subtract the
mass number from the atomic number
The subatomic particle that J.J. Thomson discovered has a(an) ____________________ charge.
negative
The difference between a sample of heavy water and regular water is that a hydrogen atom in heavy water has an extra ____________.
neutron
Protons and _____________ are found in the nucleus of an atom.
neutrons
The nuclei of isotopes contain different numbers of _____________.
neutrons
If element Q has 11 protons, its atomic _____________ is 11.
number
The region in which an electron is most likely to be found is called a(an) ___________________.
orbital
Neutrons and _________________ have almost the same mass.
protons
Democritus thought that matter was made of tiny particles
that could be divided
