2.35: Atomic Number Difficulty Level: At Grade Created by: CK-12 Estimated6 minsto complete % Progress Practice Atomic Number MEMORY METER This indicates how strong in your memory this concept is Practice Progress Estimated6 minsto complete % Estimated6 minsto complete % Practice Now MEMORY METER This indicates how strong in your memory this concept is Share Add to Library Turn In Read Practice Resources Details Loading... Notes/Highlights Having trouble? Report an issue. Color Highlighted Text Notes Show More Vocabulary Language: English ▼ English atomic mass unit (Abbreviation: amu) SI unit for the mass of an atom, where 1 amu equals the mass of a proton (about 1.7 × 10-24 grams). atomic number Number of protons in an atom. mass number Number of protons plus neutrons in an atom; equal to the atom’s mass in atomic mass units (amu). Image Attributions Show Hide Details Description Definition of atomic number and mass number. Learning Objectives None Related Materials Atomic Number Difficulty Level: At Grade Authors: Jean Brainard, Ph.D. Tags: atomic mass unit (amu) atomic number mass number (2 more) SCI.CHE.213.2.L.1 SCI.PSC.121.32.L.1 Subjects: science Physical Science Concept Nodes: SCI.PSC.121.32 (Atomic Number) Grades: 7 , 8 Date Created: Oct 31, 2012 Last Modified: Sep 13, 2016 Vocabulary None Save or share your relevant files like activites, homework and worksheet.To add resources, you must be the owner of the Modality. Click Customize to make your own copy.