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# 5.1: Chapter 5: Atoms

Difficulty Level: At Grade Created by: CK-12

## Chapter Overview

An atom consists of protons, neutrons, and electrons; and protons and neutrons consist of quarks. The strong force and electric force hold the atom together. An atom can be characterized by its atomic number and mass number. The history of the atom began with Democritus and included major contributions by Dalton, Thomson, Rutherford, and Bohr. Modern ideas about the atom include energy levels, orbitals, and electron clouds.

## Online Resources

See the following Web sites for appropriate laboratory activities:

This active lab is an entertaining way for students to explore atomic structure and other concepts introduced in Lesson 5.1. It uses simple materials such as laundry baskets and colored balls and does not require a science lab. You can divide the class into two teams and have them compete to do the activity with the fewest mistakes in the least amount of time. The URL provides complete instructions, extensions, assessments, diagrams, and an answer key.

The lab “Electron Probability” at the URL below is a creative way to help students understand probability distributions of electrons in the electron cloud model of the atom (Lesson 5.3).

• [mrsj.exofire.net/chem/docs/eprob_lab.doc mrsj.exofire.net/chem/docs/eprob_lab.doc]

These Web sites may also be helpful:

The URL below has links to several sites that offer information, lesson plans, simulations, hands-on activities, and online quizzes about atoms.

When you teach Lesson 5.2, students may benefit from the overview of atomic history at the following URL. It includes review questions, a summary, and exercises so students can check their comprehension.

For background information on modern atomic theory in Lesson 5.3, these URLs may be useful:

## Pacing the Lessons

Lesson Class Period(s) (60 min)
5.1 Inside the Atom 2.0
5.2 History of the Atom 2.0
5.3 Modern Atomic Theory 2.0

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Subjects:
7 , 8
Date Created:
Nov 11, 2013