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Topic 3
. - The Atomic Structure

4. Relating number of subatomic particles: Recalling concept facts

1. The atomic number of an element is always equal to the number of
1) Protons 2) Positrons 3) Neutrons 4) Electrons

2. In a neutral atom, the number of electrons is always equal to the number of
1) Protons plus neutrons 2) Protons minus neutrons 3) Protons only 4) Neutrons only

3. Nuclear charge of an atom is equal to the number of
1) Neutrons 2) Protons plus electrons 3) Neutrons plus neutrons 4) Protons

4. The mass number of an element is always equal to the number of
1) Protons plus electron 3) Neutrons plus protons
4) Neutrons plus positrons
2) Protons plus positrons

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5. The total number of nucleons in an atom is
1) Equal to the number of protons plus the number of electrons
2) Equal to the number of protons plus the number of neutrons
3) Equal to the number of protons minus the number of electrons
4) Equal to the number of protons minus the number of electrons

6. The number of neutrons in the nucleus of an atom can be determined by

1) Adding the mass number to the atomic number of the atom
2) Adding the mass number to the number of electrons of the atom
3) Subtracting the atomic number from the mass number of the atom
4) Subtracting the mass number from the atomic number of the atom

7. The number of protons in the nucleus of an unknown element can be determined by
1) Adding the mass number to the number of electrons of the element
2) Subtracting the mass number from the number of neutrons of the element
3) Adding mass number to the number of neutrons of the element
4) Subtracting the number of neutrons from the mass number of the element

5. Number of atomic particles: Determining number of atomic particles from others

1. What is the atomic number of an atom with 13 protons, 14 electrons, and 15 neutrons?

2) 14
1) 42

3) 13
4) 27

2. An atom contains 23 electrons, 21 protons, and 24 neutrons. What is the atomic number of this
atom?
1) 44 2) 23 3) 24 4) 21

3. A particle of an atom contains 26 protons, 23 electrons, and 56 neutrons. What will be the correct
atomic number for this particle?
1) 26 2) 23 3) 56 4) 33
4. What is the total number of neutron in the nucleus of a neutral atom that has 19 electrons and a
mass number of 39? 2) 20 3) 39 4) 58

1) 19

5. An atom has a mass number of 18 and 8 protons. What is the total number of nucleons in this atom?
1) 18
3) 10

4) 26

2) 8

6. What is the number of nucleons in an atom with 18 protons, 18 electrons, and 22 neutrons?
1) 40 2) 36 3) 18 4) 4

7. An atom contains 83 protons, 80 electrons, and 126 neutrons. What is the mass number of this
atom? 2) 209 3) 206 4) 46
1) 163

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