## Reflection: Grappling with Complexity Finding Atomic Mass Lab - Section 4: Publishing (Post-Lab)

This lab requires students to calculate the internal mass of washers in a film canister then divide by the mass of a single washer (canister A - representing Hydrogen) to determine the number of washers in a film canister. This replicates the process chemists employed to find the atomic mass of the elements. Many students have trouble understanding that the published atomic masses are averages of various isotopes (one type of atom with different weights) of a single element and are listed as decimal values. A misconception can occur when students think that the atomic mass may incorrectly represent a mass of partial neutrons (neutrons cut in pieces). I have students that have conceptional difficulty relating their calculated atomic mass (whole number) to an averaged published atomic mass (decimal number).

Using the Periodic Table
Grappling with Complexity: Using the Periodic Table

# Finding Atomic Mass Lab

Unit 3: Periodic Table
Lesson 3 of 6

## Big Idea: Weighted film canisters will stand-in for atoms as students try to determine atomic mass.

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105 minutes

### Sean Gillette

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