Focus On Physical Science: California Grade 8

Lesson 2: Discovering Parts of the Atom

Standards Check

1.
How did J.J. Thomson know that the particles in the cathode-ray tube were negatively charged? 3.a
A)The particles were spread evenly throughout the tube.
B)These particles were attracted to the negatively charged cathode, and he knew that like charges attract each other.
C)These particles were attracted to the positively charged anode, and he knew that opposite charges attract each other.
D)Some of the particles went veering off at large angles to the tube.
2.
The small, negatively charged particles discovered by J.J. Thomson are called __________ . 3.a
A)protons
B)electrons
C)neutrons
D)alpha particles
3.
Which of the following best describes Thomson's model of the atom? 3.a
A)electron cloud
B)solid ball the same throughout
C)small ball within a large shell containing empty space
D)ball of raisin-cookie dough with raisins representing electrons
4.
The __________ an energy level is from the nucleus, the __________ electrons it can hold. 3.a
A)farther, more tightly bound
B)farther, fewer
C)closer, more
D)farther, more
5.
Electrons in the sphere closest to the nucleus are in the __________ energy level. 3.a
A)lowest
B)highest
C)middle
D)negative
6.
How many electrons does an atom of carbon have in its outer energy level? 3.a
A)6
B)12
C)8
D)4
7.
A(n) __________ is a method of representing atoms and the electrons in their outer energy levels. 3.a
A)chemical formula
B)chemical symbol
C)electron dot diagram
D)chemical equation
8.
Rutherford called the positively charged, central part of the atom the __________ . 3.a
A)proton
B)nucleus
C)neutron
D)electron
9.
Ernest Rutherford experimented with alpha particles and thin gold foil to find out __________ . 3.a
A)the size of the electron orbit
B)the speed at which alpha particles travel
C)if Dalton's model of the atom was correct
D)if Thomson's model of the atom was correct
Grade 8
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