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```Study Guide for Atomic Structure Test (Chapter 3)
VOCABULARY WORDS YOU MUST KNOW
atomic mass (average atomic mass)
atomic number
isotope
mass number
nucleus
proton
neutron
electron
mole
Atomic mass number (amu)
This test will look at 4 topics:
1)
2)
3)
4)
History of the atom
Structure of the atom
Isotopes
Moles, including conversions from mass to moles and particles to moles.
History of the atom
You must be able to remember the roles that Aristotle, Democritus, Dalton, JJ Thompson,
Rutherford, and Bohr played in our first understandings of the atom. You should know what their
famous experiments were, and what they found because of them. You should also have a general
timeline of when they occurred.
Example would be …………Who discovered the existence of a nucleus in the atom and what
experiment did they use.
Answer…………..I would expect you to know that Ernest Rutherford had discovered it and that he
used alpha particles and gold foil in an experiment. That when the gold foil (leaf) was bombarded
with alpha particles, they would mostly pass through, except occasionally they would be
deflected by a something with mass. This is how the nucleus was first observed scientifically.
Structure of the atom
I expect everyone to be able to show their knowledge of the subatomic particle that make up an
atom; proton, neutron, and electron. You need to be able to tell me their charge and amu (atomic
mass numbers). You should also know where they exist in an atom, ie neutron and proton in the
nucleus. When presented with problems you need to be able to tell me how many proton
neutrons and electron are in an element or isotope based on limited information, such as:
If I give you the hyphen notation or nuclear symbol of an uranium isotope you should be able to
tell me how many protons, neutrons, and electrons are in that atom
Uranium-238
=protons)
92 protons ( from periodic table)
92 electrons (because electrons
146 neutrons (remaining mass after protons are subtracted)
Isotopes
Remember isotopes are just atoms of elements that have different numbers of neutrons. Isotopes
do not have different properties other than mass. Be careful to recall that number of protons
determine an element not neutrons.
Since neutrons exist we must be able to determine their abundance and take them into account
in our atomic mass. You will need to be able to determine the average atomic mass by calculating
the percent abundance of isotopes of different elements.
Remember to do this you must:
1) Determine the mass of each isotope and its percent abundance
2) Take the percent and put it into a decimal percentage (divide it by 100)
3) multiply the mass of the isotopes by their decimal percentages
4) add them up and this should be the average atomic mass of the element
Moles
So, we will be using the mole the rest of the year, remember the mole is a unit. Just like we say a
dozen for units of twelve, we say mole for 6.022 x 1023 of something. The mole helps us convert
molecules or atoms into mass (grams). Please look over you notes on and the figure 11 in chapter three
to help visualize how we convert between the three.
```
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