Name
Date
Period
Workbook Activity
Chapter 8, Lesson 2
49
Later Atomic Theories Directions Use the terms in the Word Bank to complete the paragraph. Write the terms on the lines. Word Bank
Ernest Rutherford sent a beam of 1. ______________, or helium nuclei, at a piece of gold foil. He expected the particles to 2. _______________. A few of them appeared to 3. _______________ at odd angles. Rutherford decided atoms must contain 4. _______________, small dense centers containing 5. _______________. (Neutrons were discovered later.) Rutherford proposed that the rest of the atom is empty space and 6. ______________.
alpha particles bounce back electrons nuclei pass through protons
Directions The table compares the subatomic particles of an atom. Complete the table. Particle
Symbol
Electron
e−
9.
p+
Neutron
11.
Charge
Mass (g) 9.110×10–28
7.
1+ 0
Location 8.
10.
1.675×10–24
Inside nucleus 12.
Directions Answer each question on the lines. Use complete sentences. 13. What was the problem before the neutron was discovered?
14. Which atom contains no neutrons in the nucleus?
15. How is Bohr’s model different from Rutherford’s?
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Chemistry