Page 20 - Utah Science Textbook
P. 20
Rutherford's Atomic Model
Rutherford’s discoveries meant that Thomson’s plum pudding model was incorrect.
Positive charge is not spread out everywhere in an atom. It is all concentrated in the tiny
nucleus. The rest of the atom is empty space, except for the electrons moving randomly
through it. In Rutherford’s model, electrons move around the nucleus in random orbits.
He compared them to planets orbiting a star. That’s why Rutherford’s model is called the
planetary model. You can see it in Figure 6.
Figure 6. This model shows Rutherford’s idea of the atom. How does it compare with Thomson’s
plum pudding?
Neils Bohr
Rutherford’s model of the atom was better than earlier models. But it
wasn’t the last word. Danish physicist Niels Bohr created a more
accurate and useful model. Bohr’s model was an important step in the
development of modern atomic theory. The video at the URL below
is a good introduction to modern atomic theory. It also reviews
important concepts from the previous two lessons, "Inside the Atom"
and "History of the Atom."
http://www.khanacademy.org/video/introduction-to-the-atom?playlist=Chemistry
21
Rutherford’s discoveries meant that Thomson’s plum pudding model was incorrect.
Positive charge is not spread out everywhere in an atom. It is all concentrated in the tiny
nucleus. The rest of the atom is empty space, except for the electrons moving randomly
through it. In Rutherford’s model, electrons move around the nucleus in random orbits.
He compared them to planets orbiting a star. That’s why Rutherford’s model is called the
planetary model. You can see it in Figure 6.
Figure 6. This model shows Rutherford’s idea of the atom. How does it compare with Thomson’s
plum pudding?
Neils Bohr
Rutherford’s model of the atom was better than earlier models. But it
wasn’t the last word. Danish physicist Niels Bohr created a more
accurate and useful model. Bohr’s model was an important step in the
development of modern atomic theory. The video at the URL below
is a good introduction to modern atomic theory. It also reviews
important concepts from the previous two lessons, "Inside the Atom"
and "History of the Atom."
http://www.khanacademy.org/video/introduction-to-the-atom?playlist=Chemistry
21
