CEM 141 EXAM 1 EXAM WITH
CORRECT QUESTIONS AND ANSWERS
2025
Make an argument for the existence of atoms. - CORRECT-ANSWERSWe know atoms exist
because we now have advanced technology that allows us to see them. Atomic force
microscopy (AFM) and scanning tunnel microscopy (STM) provide images at the atomic
levels.
Make an argument for the existence of electrons. - CORRECT-ANSWERSWe know that
electrons exist because of Thomson's cathode ray experiment. Thomson inserted a piece of
metal at the back of the tube called a cathode. He also had another piece of metal called an
anode with a small hole in the center of it. There is a current running back and forth between
the cathode and anode, and when a small amount of particles go through the hole in the
anode, it forms a ray. At the other end of the tube, there was a positively charged object on
, the top of the tube and a negatively charged object at the bottom of the tube. The ray
continuously bent upwards towards the positive object despite changing the metal the
cathode was made of. This proves that electrons exist and have a negative charge.
Make an argument for the existence of a small, massive, positively charged nucleus. -
CORRECT-ANSWERSWe know that atoms have small, massive, positively charged nucleus
because of Rutherford's gold foil experiment. Rutherford shot a ray of alpha particles
(positive) through a piece of gold foil surrounded by a circular ring. Most of the particles went
directly through the foil, but some were deflected. Since only a small amount of alpha particles
were deflected, we know that the nucleus is small, massive and positively charged.
Draw diagrams and pictures of the models of the atom as they changed over time. -
CORRECT-ANSWERSSee notes
Use the models to explain how and why the model of the atom changeover time as new
evidence arose. - CORRECT-ANSWERSAt first, Thomson believed that electrons were
CORRECT QUESTIONS AND ANSWERS
2025
Make an argument for the existence of atoms. - CORRECT-ANSWERSWe know atoms exist
because we now have advanced technology that allows us to see them. Atomic force
microscopy (AFM) and scanning tunnel microscopy (STM) provide images at the atomic
levels.
Make an argument for the existence of electrons. - CORRECT-ANSWERSWe know that
electrons exist because of Thomson's cathode ray experiment. Thomson inserted a piece of
metal at the back of the tube called a cathode. He also had another piece of metal called an
anode with a small hole in the center of it. There is a current running back and forth between
the cathode and anode, and when a small amount of particles go through the hole in the
anode, it forms a ray. At the other end of the tube, there was a positively charged object on
, the top of the tube and a negatively charged object at the bottom of the tube. The ray
continuously bent upwards towards the positive object despite changing the metal the
cathode was made of. This proves that electrons exist and have a negative charge.
Make an argument for the existence of a small, massive, positively charged nucleus. -
CORRECT-ANSWERSWe know that atoms have small, massive, positively charged nucleus
because of Rutherford's gold foil experiment. Rutherford shot a ray of alpha particles
(positive) through a piece of gold foil surrounded by a circular ring. Most of the particles went
directly through the foil, but some were deflected. Since only a small amount of alpha particles
were deflected, we know that the nucleus is small, massive and positively charged.
Draw diagrams and pictures of the models of the atom as they changed over time. -
CORRECT-ANSWERSSee notes
Use the models to explain how and why the model of the atom changeover time as new
evidence arose. - CORRECT-ANSWERSAt first, Thomson believed that electrons were
