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WorksheetsUNIT 3 - GRADE 7 - Understanding the Atom
Total questions: 22
Worksheet time: 11mins
Which part of an atom makes up most of its volume?
. its electron cloud
its neutrons
its nucleus
. its protons
. What did Democritus believe an atom was?
a tiny nucleus with electrons surrounding it
. a nucleus surrounded by an electron cloud
a tiny particle with a nucleus
a solid, indivisible object
If an ion contains 10 electrons, 12 protons, and 13 neutrons, what is the ion’s charge?
2 –
1 –
. 2+
. 3+
. J.J. Thomson’s experimental setup is shown below
What is happening to the cathode rays?
They are attracted to the negative plate.
They are attracted to the positive plate
They are stopped by the plates.
They are unaffected by either plate.
. How many neutrons does iron-59 have?
. 30
33
56
59
. Why were Rutherford’s students surprised by the results of the gold foil experiment?
. They didn’t expect the alpha particles to bounce back from the foil.
. They didn’t expect the alpha particles to continue in a straight path.
ontinue in a straight path. C. They expected only a few alpha particles to bounce back from the foil.
hey expected the alpha particles to be deflected by electrons.
Which determines the identity of an element?
. its mass number
its mass number B. the charge of the atom
the number of its neutrons
the number of its protons
The figure below shows which of the following?
two different elements
. two different ions
two different isotopes
two different protons
. How is Bohr’s atomic model different from Rutherford’s model?
. How is Bohr’s atomic model different from Rutherford’s model?
Bohr’s model has electrons.
. Electrons in Bohr’s model are located farther from the nucleus.
. Electrons in Bohr’s model are located in circular energy levels
Which best describes an atom?
a particle with a single negative charge
a particle with a single positive charge
the smallest particle that still represents a compound
the smallest particle that still represents an element
Use the figure below to answer questions 2 and 3.
What is Structure X?
an electron
a neutron
a nucleus
a proton
Which best describes Structure X?
most of the atom’s mass, neutral charge
most of the atom’s mass, positive charge
very small part of the atom’s mass, negative charge
very small part of the atom’s mass, positive charge
Which is true about the size of an atom?
It can only be seen using a scanning tunneling microscope.
It is about the size of the period at the end of this sentence
It is large enough to be seen using a magnifying lens.
It is too small to see with any type of microscope
Whose model for the atom is shown
Bohr’s
Dalton’s
Rutherford’s
Thomson’s
What structure did Rutherford discover?
the atom
the electron
the neutron
the nucleus
What is atomic number of particle 3?
3
5
6
11
Which particles are isotopes of the same element?
1 and 2
2 and 3
2 and 4
3 and 4
Which particle is an ion?
1
2
3
4
Which reaction starts with a neutron and results in the formation of a proton and a high-energy electron?
alpha decay
beta decay
the formation of positive ion
the formation of negative ion
An element’s average atomic mass is calculated using the masses of its
. electrons.
isotopes.
neutrons.
protons.
Why have scientists only recently been able to see atoms?
. Atoms are too small to see with ordinary microscopes.
Early experiments disproved the idea of atoms.
. Scientists didn’t know atoms existed.
Scientists were not looking for atoms.
. What is an atom mostly made of?
. air
empty space
neutrons
protons
