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Atomic Structure Introduction Practice Tests

These Grade 8 Science practice tests cover atoms, nuclei, protons, neutrons, electrons, atomic number, mass number, isotopes, ions, valence electrons, energy levels, atomic models, and periodic-table patterns.

Skills covered

  • Identifying the location, charge, and role of protons, neutrons, and electrons
  • Using atomic number and mass number to determine atomic structure
  • Distinguishing isotopes, ions, cations, anions, elements, and compounds
  • Connecting valence electrons and energy levels to periodic-table patterns
  • Using evidence and models to explain how scientific ideas about atoms develop

How to use these practice tests

Start with the proton number because it identifies the element. Then use mass number to find neutrons and compare protons with electrons to determine charge. Use the periodic table and atomic models to check the result.

For more Grade 8 Science practice, return to the Grade 8 Science category.

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Grade 8 Atomic Structure Introduction Practice Tests

Practice Grade 8 Science questions about atoms, protons, neutrons, electrons, nuclei, atomic number, mass number, isotopes, ions, and periodic-table patterns.

Choose the best answer for each question. Use proton number, mass number, charge, electron arrangement, and periodic-table patterns to analyze atomic structure.

10 Questions
0/10 Questions0 %
Correct 0
Incorrect 0
Unanswered 10
1. QuestionMultiple choice

An atom has atomic number 12 and mass number 24. How many neutrons does it have?

Please select an answer first.

Correct answer: A

The correct answer is 12.

  1. Identify the atomic information: Find the numbers of protons, neutrons, and electrons or identify the particle, model, element, isotope, or ion being described.
  2. Apply the relationship: Use atomic number for protons, mass number for protons plus neutrons, and net charge for the difference between protons and electrons.
  3. Check the model: Confirm that the conclusion matches the structure of the atom and the evidence represented by the diagram, notation, or periodic table.

Neutrons equal mass number minus atomic number, so 24 minus 12 is 12.

2. QuestionMultiple choice

Which notation describes an atom with 17 protons and 18 neutrons?

Please select an answer first.

Correct answer: B

The correct answer is Chlorine-35.

  1. Identify the atomic information: Find the numbers of protons, neutrons, and electrons or identify the particle, model, element, isotope, or ion being described.
  2. Apply the relationship: Use atomic number for protons, mass number for protons plus neutrons, and net charge for the difference between protons and electrons.
  3. Check the model: Confirm that the conclusion matches the structure of the atom and the evidence represented by the diagram, notation, or periodic table.

The atomic number 17 identifies chlorine, and 17 protons plus 18 neutrons gives mass number 35.

3. QuestionMultiple choice

An ion has 13 protons and 10 electrons. What is its charge?

Please select an answer first.

Correct answer: C

The correct answer is Positive three.

  1. Identify the atomic information: Find the numbers of protons, neutrons, and electrons or identify the particle, model, element, isotope, or ion being described.
  2. Apply the relationship: Use atomic number for protons, mass number for protons plus neutrons, and net charge for the difference between protons and electrons.
  3. Check the model: Confirm that the conclusion matches the structure of the atom and the evidence represented by the diagram, notation, or periodic table.

Three more positive protons than negative electrons produce a positive three charge.

4. QuestionMultiple choice

An atom has 16 protons, 16 electrons, and 18 neutrons. Which description is correct?

Please select an answer first.

Correct answer: D

The correct answer is A neutral sulfur atom with mass number 34.

  1. Identify the atomic information: Find the numbers of protons, neutrons, and electrons or identify the particle, model, element, isotope, or ion being described.
  2. Apply the relationship: Use atomic number for protons, mass number for protons plus neutrons, and net charge for the difference between protons and electrons.
  3. Check the model: Confirm that the conclusion matches the structure of the atom and the evidence represented by the diagram, notation, or periodic table.

Sixteen protons identify sulfur, equal electrons make it neutral, and 16 plus 18 gives mass number 34.

5. QuestionMultiple choice

How many atoms are in one molecule of water, H2O?

Please select an answer first.

Correct answer: A

The correct answer is Three atoms.

  1. Identify the atomic information: Find the numbers of protons, neutrons, and electrons or identify the particle, model, element, isotope, or ion being described.
  2. Apply the relationship: Use atomic number for protons, mass number for protons plus neutrons, and net charge for the difference between protons and electrons.
  3. Check the model: Confirm that the conclusion matches the structure of the atom and the evidence represented by the diagram, notation, or periodic table.

The formula has two hydrogen atoms and one oxygen atom, for three atoms total.

6. QuestionMultiple choice

What is conserved during an ordinary chemical reaction?

Please select an answer first.

Correct answer: B

The correct answer is The types and numbers of atoms are rearranged but conserved..

  1. Identify the atomic information: Find the numbers of protons, neutrons, and electrons or identify the particle, model, element, isotope, or ion being described.
  2. Apply the relationship: Use atomic number for protons, mass number for protons plus neutrons, and net charge for the difference between protons and electrons.
  3. Check the model: Confirm that the conclusion matches the structure of the atom and the evidence represented by the diagram, notation, or periodic table.

Chemical reactions rearrange atoms into new combinations while conserving the atoms involved.

7. QuestionMultiple choice

What is the difference between an element and a compound?

Please select an answer first.

Correct answer: C

The correct answer is An element contains one type of atom, while a compound contains two or more elements chemically combined..

  1. Identify the atomic information: Find the numbers of protons, neutrons, and electrons or identify the particle, model, element, isotope, or ion being described.
  2. Apply the relationship: Use atomic number for protons, mass number for protons plus neutrons, and net charge for the difference between protons and electrons.
  3. Check the model: Confirm that the conclusion matches the structure of the atom and the evidence represented by the diagram, notation, or periodic table.

Elements are defined by one proton type, while compounds combine different elements in fixed relationships.

8. QuestionMultiple choice

An element is in the same group as another element with seven valence electrons. What property might it share?

Please select an answer first.

Correct answer: D

The correct answer is A tendency to gain one electron in many reactions.

  1. Identify the atomic information: Find the numbers of protons, neutrons, and electrons or identify the particle, model, element, isotope, or ion being described.
  2. Apply the relationship: Use atomic number for protons, mass number for protons plus neutrons, and net charge for the difference between protons and electrons.
  3. Check the model: Confirm that the conclusion matches the structure of the atom and the evidence represented by the diagram, notation, or periodic table.

Elements with seven valence electrons often gain one electron to reach a more stable outer arrangement.

9. QuestionMultiple choice

Why is a neutral atom not electrically charged overall?

Please select an answer first.

Correct answer: A

The correct answer is Its positive proton charge equals its negative electron charge..

  1. Identify the atomic information: Find the numbers of protons, neutrons, and electrons or identify the particle, model, element, isotope, or ion being described.
  2. Apply the relationship: Use atomic number for protons, mass number for protons plus neutrons, and net charge for the difference between protons and electrons.
  3. Check the model: Confirm that the conclusion matches the structure of the atom and the evidence represented by the diagram, notation, or periodic table.

Equal numbers of protons and electrons make the total charge zero.

10. QuestionMultiple choice

Which statement best summarizes atomic structure?

Please select an answer first.

Correct answer: B

The correct answer is The nucleus contains protons and neutrons, while electrons occupy regions around it and determine many chemical interactions..

  1. Identify the atomic information: Find the numbers of protons, neutrons, and electrons or identify the particle, model, element, isotope, or ion being described.
  2. Apply the relationship: Use atomic number for protons, mass number for protons plus neutrons, and net charge for the difference between protons and electrons.
  3. Check the model: Confirm that the conclusion matches the structure of the atom and the evidence represented by the diagram, notation, or periodic table.

The summary correctly connects the nucleus, electron region, and chemical behavior.

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