Lesson 2: Atomic Structure
Day 2
Activity 3: A Timeline of Discoveries
Materials: glue stick, scissors
For this activity you will learn about several important scientists and their discoveries. You will create a timeline representing the chronology of their discoveries and what each discovery was. Ask your parent which option to complete.
You may find the following links useful:
You may find the following links useful:
Web Link
J.J. Thomson — 3 Experiments, 1 Big Idea
Also click the "Corpuscles to Electrons" link at the bottom of the page to learn more about J.J. Thomson.
This link was verified on 10/28/2023.
Web Link
Web Link
Web Link
Ernest Rutherford — Planetary Model of the Atom
This link was verified on 11/10/2023.
Web Link
Web Link
Student Activity Page
Help decide which option your child should complete for this activity. The first option is easier and better if you have less time. The second option encourages your child to do her own research and will be a good option for students particularly interested in science and its development over time.
Option 1: Learning about Discoveries
For this option, read the information on the "Scientists" (Option 1) page. Next, cut out each rectangle and paste it on the sheet, "A Timeline to Figuring Out the Pieces" (Options 1 and 2). Use the links for this activity to learn more about any scientists or discoveries that interest you.
Student Activity Page
For this option, your child will paste information in the appropriate place on a timeline. Encourage her to use the links to learn more about scientists or discoveries that interest her. Refer to the answer key for Option 2 for the correct dates.
Option 2: Researching Discoveries
For this option, read the information provided in the links for this activity and take notes about each scientist's discoveries related to atoms. Use the "Scientists" (Option 2) page to write one or two of the scientists' major discoveries. Next, cut out each rectangle and paste it on the sheet, "A Timeline to Figuring Out the Pieces" (Options 1 and 2).
Student Activity Page
You can review your child's answers for either option using the following key:
J. J. Thomson (1890s): through his work on cathode rays in 1897, he discovered electrons and concluded that they were a component of every atom. Thomson assumed that negatively charged electrons were distributed throughout the atom. He developed what was known as the plum pudding model.
Ernest Rutherford (Hans Geiger and Ernest Marsden) (1909): blasted a sheet of gold foil with alpha rays (positively charged helium atoms) and discovered that the particles were deflected. Rutherford understood the gold foil experiment to suggest the positive charge of a heavy gold atom and that most of its mass was concentrated in a nucleus at the center of the atom.
Frederick Soddy/Margaret Todd (1913): discovered that there appeared to be more than one type of atom at each position on the periodic table. The term isotope was coined by Margaret Todd as a suitable name for different atoms that belong to the same element.
Niels Bohr (1913): suggested that electrons were confined to orbits and could jump between different orbits. This did not occur freely but required the addition or subtraction of energy to the atom.
Erwin Schrödinger (1920's): developed a mathematical model of the atom that described the electrons as three-dimensional; ideas included considering the electron as a wave rather than as a small piece (or point) of matter.
J. J. Thomson (1890s): through his work on cathode rays in 1897, he discovered electrons and concluded that they were a component of every atom. Thomson assumed that negatively charged electrons were distributed throughout the atom. He developed what was known as the plum pudding model.
Ernest Rutherford (Hans Geiger and Ernest Marsden) (1909): blasted a sheet of gold foil with alpha rays (positively charged helium atoms) and discovered that the particles were deflected. Rutherford understood the gold foil experiment to suggest the positive charge of a heavy gold atom and that most of its mass was concentrated in a nucleus at the center of the atom.
Frederick Soddy/Margaret Todd (1913): discovered that there appeared to be more than one type of atom at each position on the periodic table. The term isotope was coined by Margaret Todd as a suitable name for different atoms that belong to the same element.
Niels Bohr (1913): suggested that electrons were confined to orbits and could jump between different orbits. This did not occur freely but required the addition or subtraction of energy to the atom.
Erwin Schrödinger (1920's): developed a mathematical model of the atom that described the electrons as three-dimensional; ideas included considering the electron as a wave rather than as a small piece (or point) of matter.
Activity 4: Vocabulary Review
To close out the lesson, review vocabulary terms using the "Vocabulary Review" pages provided. Cut out the boxes on each page and then mix the cards up. Match each term with the appropriate illustration. You may also want to use the cards to play a game of Memory. Also refer to the "Things to Know" section at the beginning of the lesson and make sure you are familiar with the words' definitions.
Student Activity Page
Student Activity Page
This activity will help your child review the terms introduced in this lesson.
If your child has extra time or you think she could use additional reinforcement of the lesson's vocabulary, ask her to also complete the "Activity Extension" section.
If your child has extra time or you think she could use additional reinforcement of the lesson's vocabulary, ask her to also complete the "Activity Extension" section.
Activity Extension
For additional review of the vocabulary, write the definitions of the words on the back of each vocabulary card you used in Activity 4. Hold onto these so that you can review the words over the course of the unit.