Download Atomic Theory and the Nuclear Atom

Atomic Theory and the Nuclear Atom
Unit 2 Page 1
Learning Target:
I can the experimental design and conclusions used in the development of modern atomic theory, including Dalton's
Postulates, Thomson's discovery of electron properties, Rutherford's nuclear atom, and Bohr's nuclear atom.
Criteria for Success:
I can explain the contributions of Dalton, Thomson, Rutherford and Bohr to the modern atomic theory.
I can describe the models of the atom that Dalton, Thomson, Rutherford and Bohr proposed.
I can identify which experiment and results lead to which discovery for Dalton, Thomson, Rutherford and Bohr.
Mini-Lab: Constructing a Model
Introduction
There are many things in science that are modeled that cannot be seen. One of the most famous models of something
that is not able to be seen is the atom. How are scientists able to construct models of things that they cannot see? You
will practice constructing a model of an unknown object by making inferences about an object that is in a closed
container and then touching the object without seeing it.
Procedure
1. Your teacher will provide you with a cup that is covered by a sock sealed with tape and a rubber band. Without
unsealing the container or sock, try to determine the number of objects inside the cup as well as the mass, shape, size,
composition, and texture of each. To do this, you may carefully tilt or shake the cup. Record your observations in Data
Table 1: Constructing a Model beneath the column Indirect Observations.
2. Remove the rubber band from the top of the sock. Do NOT look inside the cup. Put one hand through the opening
and make the same observations as in step 1 by touching the objects while in the cup. To make more accurate
estimations, practice estimating the sizes and masses of some known objects outside the cup using a metric ruler and a
balance. Then compare your estimates of the objects inside the cup with the known objects outside the cup. Record
your observations in Data Table 1: Constructing a Model beneath the column Direct Observations.
3. Make a sketch a model of what you believe the object inside the can might look like in Data Table 1: Constructing a
Model beneath the column Model of Object.
4. At the direction of your instructor you may take out one of the objects from the cup and determine how close you
came with your estimates!
Data
Data Table 1: Constructing a Model
Cup #
Indirect Observations
Direct Observations
Model of Object
Atomic Theory and the Nuclear Atom
Unit 2 Page 2
Notes
Atomic Theory
A. ___________________ is anything that has mass and takes up space.
1. All matter is made up of ___________.
Development of Atomic Model
A. In approximately 400 B.C.E., the idea that all matter is made up of extremely small, solid, _____________________
particles called atoms was first proposed by Greek thinkers, such as _________________.
B. In 1808 C.E., John ______________ expanded on this theory and proposed an atomic theory with several points
1. All __________________ are composed of tiny, indivisible particles called ____________.
2. Atoms of the same element are __________________. The atoms of any one element are
_____________________ from those of any other element.
3. Atoms of different elements can physically mix together or can chemically combine in simple,
____________________ ______________ to form ___________________.
4. Chemical _________________ occur when atoms are separated from each other, joined, or rearranged in
different combinations. Atoms of one element, however, are never changed into atoms of another element as a
result of a chemical reaction.
C. In 1897 C.E., Joseph John ________________ revised our understanding of atomic theory by proposing that atoms
COULD be ___________________.
1. Thomson concluded from his experiments with _____________ _____ that atoms actually contained small
________________ charged particles.
D. In 1911 C.E., Ernest _________________ expanded our understanding even further.
1. In his famous _________________ experiment, Rutherford concluded that the atom consisted of a very small,
positively charged region, called the ______________, and that it was surrounded by small negatively charged
particles.
E. In 1913 C.E., Niels ___________ expanded on Rutherford’s model by theorizing that the negatively charged particles
existed in specific __________.
1. Niels __________ model of the atom was developed in relation with the study of the hydrogen
_______________ spectrum.
F. In the early 20th century, several scientists including __________________, _____________________, and
______________________ contributed to our current understanding of the structure of the atom by elaborating on
Bohr’s orbits. They more accurately described the region that the negative particles of the atom existed in as
_______________.
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