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Physical ScienceGrade 7-9

Atomic Structure Answer Key

Build atoms and understand how protons, neutrons, and electrons determine element identity.

Looking for Atomic Structure answers? This complete answer key provides verified solutions for all student exploration activities and assessment questions in the ExploreLearning Atomic Structure Gizmo.

100% Free • Step-by-step explanations • Perfect for homework help • Covers all activities • Updated for 2026

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Subatomic Particles

Q1.Where are electrons located?

Answer

In electron shells (energy levels) surrounding the nucleus.

Q2.What determines an element's identity?

Answer

The number of protons (atomic number). Carbon always has 6 protons.

Q3.What are isotopes?

Answer

Atoms of the same element with different numbers of neutrons. Example: Carbon-12 and Carbon-14.

Electron Configuration

Q4.How many electrons fit in the first shell?

Q5.How many electrons fit in the second shell?

Q6.What are valence electrons?

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