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M7
THE ATOM
Foundational Research Package
II
A CLOSER LOOK AT THE STRUCTURE OF MATTER
December 2007 - Team E Science
ANSWERS
TABLE OF CONTENTS
Introduction, Objectives and Study Guide………..1
Research and Practice
Properties of Atoms…………………………..2-6
The Bohr Model Revisited..…………………...7-8
The Periodic Table……………………………9-14
We have just concluded our intro to the heart of the matter. From this
experience, we were able to discover:
1)
2)
3)
4)
the
the
the
the
classes of matter.
history of the atom.
structure of the atom.
forces of the atom.
We are now going to get deeper into the heart of the matter with a look at
the following questions and concepts.
PROBLEM 1: How do we distinguish between the atoms of different elements?





THE FIVE PROPERTIES OF ATOMS
Chemical Symbol
Chemical Name
Atomic Mass
Atomic Number
Mass Number (and Isotopes)
PROBLEM 2: How do we illustrate the structure of the atom?
THE BOHR MODEL
 Determination of number of subparticles
 Placement of subparticles
 Predicting bonding
PROBLEM 3: How do we organize the elements for studying purposes?
THE PERIODIC TABLE
 Periods/Rows vs. Columns
 Meaning of column #’s
 Families: Non-metals, Metals, Metalliods, Inert/Noble Gases
Now that you know what we’ve got to learn, let’s get a-learning…NOW!
FYI – your quiz on these questions is planned for NEXT THURSDAY…December
20th! You will be asked to answer questions on ONE element. This packet, as
well as your review packet (M-8), will be the materials you need to study for this
quiz.
PROBLEM #1
How do we distinguish between the atoms of different elements?
A closer look at the properties (i.e. characteristics) of the atom
In this section of our closer look at the atom, we will take a look at how we distinguish between the
atoms of different elements. First, let’s define what a “property” is and why it is important in studying
atoms.
What is a “property” of an atom and why do we need to refer to these “properties” when we are
talking about atoms?
_______IT IS A CHARACTERISTIC OF AN ATOM THAT HELPS US TO ID WHAT ELEMENT IT IS
_______________________________________________________________________________________
There are FIVE properties of atoms that you need to know about and understand. They are…
Property
Definition
The first two properties, the chemical __NAME___ and
Chemical
__SYMBOL___, are the ways that we label or “call” or “name” atoms.
Name
and
The symbol comes from the first letter or letters in the chemical’s
Symbol
____ENGLISH_________ or ____LATIN__________ name.
The third property, _ATOMIC_____ __NUMBER____, is equal to
the number of protons OR electrons. It is the property that gives an
Atomic
Number
atom the chemical characteristics that make it different from other
atoms.
Why? Because if you change the number of _p+_____ and
__Ø_____ in an atom, you are changing its IDENTITY and all that
makes it what it is (i.e. its ___PROPERTIES______) and what it can do
with other atoms (i.e. __BOND!________).
Location in an
entry on
Periodic Chart
The fourth property, the ____ATOMIC_____ _____MASS______,
tells us how much “matter” or ___MASS________ or a.m.u.’s there
is/are in the _AVERAGE______atom of an element (i.e. the number of
Atomic
Mass
_p+___ and __Ø__ ). Why is there an average mass? The mass of an
element can be different from atom to atom of that element. This is
because __# OF p+____can never change for a given atom, but __ Ø
______ can because they have a ___NEUTRAL____ charge and therefore
will not change the atom’s identity but will change its ____MASS___.
The fifth property, the _MASS_____ __NUMBER____, is the
Mass
Number
___ACTUAL______ mass of an __ACTUAL____ atom…not the
_AVERAGE MASS___ from the periodic chart. Therefore, it is the
__ACTUAL___ amount of __p+_____ and ___ Ø ____ in an _ACTUAL_
atom. This __ACTUAL__ sample of an element is called an _ISOTOPE_.
AN ENTRY FROM THE PERIODIC TABLE…
Identify the properties in this entry from the periodic table.
__ATOMIC #____
_____CHEM SYMBOL___
1
____________________
H
___CHEM NAME________
______ATOMIC MASS_______
Hydrogen
1
Now assume you are given an isotope for Hydrogen. We identify an isotope by writing its chemical
name OR symbol followed by a dash and then its mass number. An example isotope of Hydrogen is
Hydrogen-2 or H-2. How would this isotope of Hydrogen be different from the average atom that is
listed on the Periodic Table?
_ATOMIC #_______
_1_
____IT WOULD HAVE 1 MORE Ø THAN THE AVERAGE ON THE
H
Hydrogen
_2_
__MASS #______
PERIODIC TABLE__________________________________________________
_________________________________________________________________
Copper
(Cu)
Helium
(He)
Boron
(B)
Magnesium
(Mg)
Lead
(Pb)
Chemical
Name
Cu-60
He-3
B-11
Mg-28
Pb-207
Isotope
(Actual
Sample)
64
4
11
24
207
Atomic
Mass
29
2
5
12
82
Atomic
Number
60
3
11
28
207
Mass
Number
29
4
5
12
82
Electrons
29
4
5
12
82
Protons
35
2
6
12
125
Average
Neutrons
31
1
6
16
125
Isotope
Neutrons
4 less than
average
1 less than
average
Same as
average
4 more
than
average
Same as
average
Difference?
PART I. PROPERTIES OF ATOMS PRACTICE PROBLEMS
Below is a list of the properties of isotopes of five different elements. Use the information given to you, your notes on
properties of atoms, and the periodic chart in your green folder to fill in the missing information.
PART II. USES OF ISOTOPES
So…what’s the big deal about isotopes? Why is it so important that there are atoms of the same
element that have different amount of neutrons?
To figure this out…
Pick an isotope from the attached list.
Read the information about your selected isotope.
Grab your periodic table.
Answer the following questions.
1) Pick one of the isotopes and write its name here:_________________________________
2) How does the isotope you selected differ from the average atom that is shown on the
periodic chart? Fill in the information below and then explain the difference(s) (if there
is/are one/any!) in the space provided.
THE PERIODIC CHART INFO:
ISOTOPE INFO:
Atomic #
____
____
Chem.
Sym.
____
Atomic Mass
____
Mass Number
__________________________________________________________________________________________
__________________________________________________________________________________________
3) Why is the isotope you selected important? In other words, what special property does it
have and/or what do we use it for?
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
EXAMPLES OF ISOTOPES
PROBLEM #2
How do we illustrate the structure of the atom?
A FINAL and CLOSER look at the Bohr Model
The Bohr Model is something that should be relatively familiar to you…but NOW is the time to really get a grip
on it! WARNING! This might just be a little “Bohring” since you already know a bit about it!
SO, hot-shot scientists, let’s see what you know by trying to fill out the important info about the Bohr Model in
the space below…
THE PURPOSE OF THE BOHR MODEL
The purpose of the Bohr model is to:
1) _____Predict structure of atom_____________________________________________________________
2) _____Predict bonding – valence shell “emptiness” predicts if atom will bond and how it will bond_______
THE PROCEDURE FOR MAKING A BOHR MODEL – this works for the first _____ elements ONLY!
1) Get a __PERIODIC_____ ____TABLE___!!! (or look at the info given about an isotope of an element)
2) Find the number of __p+__ in the atom by looking at the atomic __#________ for that atom.
3) Find the number of __e-____ in the atom by looking at the atomic __#______ again. This is same
number as the number of _p+__ because atoms must be __NEUTRAL (i.e. no charge)_____.
4) Find the number of __ø____ by _____SUBTRACTING ___ the atomic __#______ FROM the atomic
___MASS________ (or mass ____#______ if an isotope).
5) Draw the ___NUCLEUS ____ as a circle. Put the ___CHEM_____ ___SYMBOL__ and the number of
_____p+___ and ____ ø ___ in the circle.
6) Fill the __ENERGY__ ___LEVELS___ with the right number of __e-______ according to the pattern of
_2__ - __8_ - __8_ ! Do ___NOT_____ fill a new ___ENERGY___ ____LEVEL__ until the level you
are in is filled to its ___MAX__________ capacity!
7) Remember, for all subatomic particles it is necessary to put the ___#_______ before the __SYMBOL___
when listing the amount of the sub particles in the atom!
LET’S DO SOME “BOHRING” PRACTICE!
1) Do the Bohr Model for an isotope of Aluminum
13
Al
26
Al
2 e-
8 e-
3e-
13 p+
13 Ø
Is this isotope of Aluminum different from the average isotope of Aluminum? Explain your answer.
____Yes – it has one less neutron than the average_______________________________________
2) Do the Bohr Model for an isotope of Sulfur
16
S
32
S
16 p+
16Ø
2 e-
8 e-
6e-
Is this isotope of Sulfur different from the average isotope of Sulfur? Explain your answer.
______No, mass number =atomic mass__________________________________________________________
3) Do the Bohr Model for an isotope of ?????????????
10
?
20
Ne
10 p+
10 Ø
2 e-
8e-
What is the identity of the mystery isotope? Is this isotope different from an average isotope of that element?
Explain your answer.
____Neon – no, has same amount of neutrons/atomic mass___________________________________
Will this atom bond with other atoms? Why or why not?
________No – has a full valence shell_____________________________________________
PROBLEM #3
How do organize the elements for studying purposes?
A look at the “periodic pattern” in the Periodic Table
DO NOW:
An isotope of oxygen has a MASS NUMBER of 9. Find oxygen on your periodic table (oxygen is located in the
3rd to last column). Use the information in your periodic table and the MASS NUMBER of this atom of
oxygen to:
1) DRAW the Bohr model for this isotope of oxygen.
2) LIST the number of subatomic particles in this isotope of oxygen.
3) LIST how many more or less neutrons this isotope of oxygen has compared with the “average” oxygen
atom.
Bohr Model:
O
2e-
6e-
e-
p+
Ø
Difference in
neutrons
8
8
1
7 less
8 p+
1Ø
ONE MORE QUESTION:
What could be the LOWEST possible MASS NUMBER for an isotope of oxygen? HIGHEST? Explain your
answers!
_________8 – because if you go lower than 8 you are taking away neutrons!____Highest…technically…infinity!__
__________________________________________________________________________________________
__________________________________________________________________________________________
INTRODUCTION TO THE PERIODIC TABLE…
The Periodic Table
A scientific problem. A periodic pattern to be discovered. Two detectives. One answer found and reformulated.
Now, for the “rest” of the story…
The Russian scientist Dmitri Medeleev was the first chemist responsible for “creating” the periodic chart of
elements. Scientists during Dmitri’s time were trying to figure out an easy way in which they could organize the
elements of matter so that it would be easy for them to communicate about their properties (i.e. scientists, even back
then, were lazy and they didn’t want to have to memorize all the elements and their properties).
Dmitri was, as are all scientists, a problem solver. His problem was to organize the elements into a predictable,
easy to understand way…he want to predictably order or .“periodically arrange” the elements in a way that relate
the elements properties to their placement in a table.
To solve this problem – to organize the elements into a table that had a periodic or predictable pattern of element
properties – Dmitri first made cards of all the known elements. On each card he wrote the element’s name and
all of its properties (e.g. atomic mass, density, color, melting point, and ability to BOND with other elements).
The ability to bond with other elements was expressed as VALENCE NUMBER. This was a number that
reflected the number of electrons that the element would want to SHARE, LOSE, or GAIN when it combined
with other elements. GET THAT? When atoms combine with one another, they either SHARE, LOSE, or
GAIN electrons in their VALENCE SHELLS. The VALENCE NUMBER is the NUMBER of electrons that an atom
will most likely LOSE, GAIN, or SHARE. This is different from the NUMBER of VALENCE ELECTRONS! The
number of valence electrons is JUST how MANY electrons there are in the VALENCE SHELL…NOT how many
the atom will most likely lose, gain, or share.
As he was “playing cards,” Dmitri fell upon a pattern. By arranging them in order of atomic mass, he noticed that
there was a pattern in the VALENCE NUMBER of the elements for EVERY SEVEN elements. The pattern was
LOSE 1 e-, LOSE 2 e-, LOSE 3e-, GAIN OR LOSE 4e-, GAIN 3e-, GAIN 2e-, GAIN 1e-. Using this pattern as his
guide and keeping to the order of increasing atomic mass, he then put the elements into columns instead of a
long strand of elements: all the elements that would lose one electron were in column one, all the elements that
would lose 2 electrons were in column two, etc. When he did this, he saw another pattern! The chart or table that
he created was predictable and periodic according to atomic mass, valence number AND several other physical and chemical
properties!
The problem of creating a chart of the elements that reflected a predictable, periodic pattern of atomic properties
had been solved…ALMOST! Some elements just didn’t seem to fit in to the pattern of increasing atomic mass and valence
numbers.
Science never stops, and the same holds true for the “creation” of the periodic table…50 years later a NEW atomic
property – ATOMIC NUMBER (the number of protons and neutrons) – was discovered by another scientist: the
Brit Henry Moseley. It was then that the pattern in the periodic table was truly founded…elements, instead of
being ordered as a function of their atomic mass, were ordered as a function of their atomic number. The
“periodic” pattern in the table of elements was based on ATOMIC NUMBER and VALENCE instead of ATOMIC MASS
and VALENCE!
…And, in the words of talk radio commentator Paul Harvey…
“that’s the ‘rest’ of the story.”
THE PROBLEM: HOW DO WE ORGANIZE THE ATOM FOR STUDYING PURPOSES?
The answer…
THE PERIODIC TABLE a.k.a. THE PERIODIC CHART a.k.a. THE TABLE OF ELEMENTS!
NOTE: Thanks to those Russian and British dudes (Mendeleev and Moseley), the periodic table is arranged in a
predictable…periodic …USEFUL way. It has a pattern to it…the properties of the elements are predictable
according to their location…they repeat themselves periodically (hence the name “periodic” table). So...USE it to
your ADVANTAGE! That’s why it’s there…that’s why it is arranged in the way that it is! YOU DON’T HAVE TO
MEMORIZE THE ELEMENTS AND THEIR CHARACTERISTICS! By using the chart often, you will
automatically become familiar with the elements and the characteristics!
Here are some important periodic patterns in our most beauteous of all chemical charts.
1. The periodic table has ____PATTERN______________________.
a) All the elements in EACH ____COLUMN____ have the same # of _VALENCE_ electrons (the same # of
electrons in the _LAST___ energy level). The main columns of the periodic table can be labeled so
that the column # is the same # as the # of __VALENCE_ electrons in the atoms in that column…thus,
_____COLUMNS______ can also be labeled with their VALENCE NUMBERS. Let’s label our
periodic charts with these numbers now.
b) Elements in the same ___COLUMN_______ DO share similar chemical and physical properties.
c) Example:
Beryllium has _4__ electrons and _4___ protons. It has __5___ neutrons.
4
The Bohr model for Beryllium is:
Be
9
It is located in column __2__. It therefore has __2__ electrons in its __VALENCE__ shell.
The Bohr model proves this! Its VALENCE NUMBER is _2___.
This means that it wants to __LOSE___ 2 electrons when it bonds with other atoms.
2. The periodic table has ___ROWS__________ or ____PERIODS_____.
a) All the elements in the each ___PERIOD____________ have the same # of __ENERGY__ levels or shells.
b) All elements in the same ___PERIOD____ do __NOT___ share similar chemical and physical properties.
c) Example:
4
6
Beryllium and Carbon are both in period _2___. The both have _2__ energy
Be
C
levels, but they do __NOT_ have similar chemical or physical properties (e.g. they
9
12
are not in the same __COLUMN_________)!
3. There are 4 major ___FAMILIES_______ or categories in the periodic table. Each ___FAMILY___ has a
unique set of properties and characteristics. Because the periodic pattern in the periodic table is based upon the
atomic ___NUMBER_____ and ___VALENCE________ number of the elements, the families are each located
in specific areas on the periodic table. The chart below outlines these families, their physical and chemical
FULL VALENCE SHELL!
STABLE!
Column 8
Noble or Inert Gases
DO NOT WANT TO BOND!
A little bit of both metallic and non-metallic properties
except for AL
On or below staircase
Metalloids
Opposite of metals
Right of staircase
Non-Metals
corrodes
Left of staircase
Metals
Lustrious, malleable, ductile, conduct and electricity,
Location on Chart
Family
Chemical and Physical Properties
properties, the types of bonds they make, and where they are located on the chart.
A “CLOSER” LOOK AT THE STRUCTURE OF MATTER
How do we illustrate the structure of the atom?
GRAPHIC ORGANIZER PRACTICE