Chapter 4 Physical Science
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?
32
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
According to ____________________, all matter was made up of four elements — earth, air, fire, and water.
Aristotle
The Greek philosopher Democritus coined what word for a tiny piece of matter that cannot be divided?
Atom
In Bohr's model of the atom, ____________________ move in fixed orbits 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
Who provided evidence for the existence of a nucleus in an atom?
Ernest Rutherford
An atom in which an electron has moved to a higher energy level is in a(an) ____________________ state.
Excited
When all the electrons in an atom are in orbitals with the lowest possible energy, the atom is in its ____________________ state.
Ground
Which statement best describes Rutherford's model of the atom?
It is like a huge stadium with a positively charged marble at the center.
What can scientists measure to provide evidence that electrons can move from one energy level to another?
Light
In Niels Bohr's model of the atom, electrons move
Like planets orbiting around the sun
The ____________________ of an isotope is the sum of the number of protons and neutrons in its nucleus.
Mass Number
The glowing of a neon light is caused by electrons emitting energy as they
Move from higher to lower energy levels
Protons and ____________________ are found in the nucleus of an atom.
Neutrons
In Rutherford's gold foil experiment, shown in Figure 4-1, alpha particles that bounce straight back from the foil have struck ____________________ in the gold atoms.
Nucleus
The region in which an electron is most likely to be found is called a(an) ____________________.
Orbital
What do scientists use to predict the locations of electrons in atoms?in
Probability
Neutrons and ____________________ have almost the same mass.
Protons
What is the difference between an atom in the ground state and an atom in an excited state?
The ground state is the lowest energy state of the atom. When the atom absorbs energy, it can move to a higher energy state, or excited state.
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 a predictable mass for a given element
The number of protons in one atom of an element is that element's
atomic number
Democritus thought that matter was made of tiny particles
could not be divide
Which subatomic particle has a negative charge?
electron
John Dalton concluded that all the atoms of a single ____________________ have the same mass.
element
To find the number of neutrons in an atom, you would subtract
like planets orbiting the sun
The nuclei of isotopes contain different numbers of ____________________.
neutrons
The diagram in Figure 4-1 shows the results of Rutherford's gold foil experiment. What caused some of the alpha particles to bounce straight back from the gold foil?
nuclei in the gold atoms
What can you assume has happened if an electron moves to a higher energy level?
the electron had gained energy
to find the number of neutrons in an atom, you would subtract _______________________________.
the mass number
Which of the following is unique for any given element?
the number of protons
What does the electron cloud model describe?
the possible locations of electrons around the nucleus
According to John Dalton's observations, when elements combine in a compound,
the ratio of their masses is always the same.
