Free Printable WorksheetScienceGrade 9Science CurriculumNGSS HS-PS1-1, HS-PS1-8

9.22 Atomic Number, Mass Number, and Isotopes Worksheet

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Worksheet Overview & Skills Covered

Core academic competencies and curriculum alignment

This Physical Science with Earth and Science Science worksheet provides structured practice on 9.22 Atomic Number, Mass Number, and Isotopes. Students are guided through targeted exercises that build foundational understanding, computational accuracy, and critical thinking skills.

Atomic Number, Mass Number, and Isotopes: MCQ focus: calculate or identify protons, neutrons, and electrons using atomic number, mass number, and isotope notation. Aligned to NGSS high school Physical Science, Earth and Space Science, and Engineering Design; NRC/DCI; SEP/CCC; CCSS math/literacy connections; selected CA NGSS, NYSSLS, Florida CPALMS, and Texas TEKS references NGSS HS-PS1-1, HS-PS1-8 - NGSS-aligned Atomic Number, Mass Number, and Isotopes: NGSS: HS-PS1-1; HS-PS1-8; NRC/DCI: PS1.A; PS1.C; SEP/CCC: Using mathematics / Scale, proportion, quantity; Common: HSN-Q.A; State refs: CA/NYSSLS same HS-PS PE family; FL SC.912.P.8; TX IPC matter strand.

Whether you are an educator preparing classroom handouts, a tutor reinforcing weekly topics, or a parent supporting homeschool learning, this printable resource gives students the deliberate practice required to achieve subject fluency and master state standards.

Grade

Physical Science with Earth and Science

Subject

Science

Domain

Science Curriculum

Formats

PDF & DOCX

Sample Practice Problems

Preview the types of problems and questions covered in this worksheet

Below are sample questions representative of the exercises included on this worksheet and related 9.22 Atomic Number, Mass Number, and Isotopes skill assessments:

Problem 1Difficulty: Mastery

A student wants an isotope with 20 protons, mass number 44, and 18 electrons. Which notation-style description fits?

Aargon-44 with a neutral charge

Bcalcium-18 with a 2+ charge

Ccalcium-44 with a 2+ charge

Dcalcium-44 with a 2- charge

Solution & Explanation:Twenty protons identify calcium. Mass number 44 gives calcium-44, and 18 electrons means two fewer electrons than protons, so the charge is 2+.

Problem 2Difficulty: Mastery

A chart groups two species: one has 12 protons, 13 neutrons, and 10 electrons; the other has 12 protons, 14 neutrons, and 10 electrons. Which conclusion is best?

AThey are sodium ions with the same mass number.

BThey are different elements because their neutron counts differ.

CThey are neutral magnesium atoms with different mass numbers.

DThey are magnesium ions that are isotopes and both have 2+ charge.

Solution & Explanation:Twelve protons identify magnesium. Both have two fewer electrons than protons, so both are 2+ ions, and the different neutron counts make them isotopes.

Problem 3Difficulty: Mastery

Which particle count set matches nickel-58 with a 2+ charge?

A30 protons, 28 neutrons, 26 electrons

B28 protons, 30 neutrons, 26 electrons

C28 protons, 30 neutrons, 30 electrons

D28 protons, 58 neutrons, 26 electrons

Solution & Explanation:Nickel has atomic number 28. Neutrons are 58 - 28 = 30, and a 2+ ion has 28 - 2 = 26 electrons.

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Frequently Asked Questions

Common questions about printing, using, and solving this worksheet

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QWhat grade level and standards does this worksheet align with?

This worksheet is designed specifically for Physical Science with Earth and Science Science students. It aligns with educational standard NGSS HS-PS1-1, HS-PS1-8 (NGSS: HS-PS1-1; HS-PS1-8; NRC/DCI: PS1.A; PS1.C; SEP/CCC: Using mathematics / Scale, proportion, quantity; Common: HSN-Q.A; State refs: CA/NYSSLS same HS-PS PE family; FL SC.912.P.8; TX IPC matter strand.).