From Few
Come Many
Copper, like dandelions and crabgrass, turns up in
many unexpected places. Copper particles are part
of the makeup of many different materials. you
found this out in Chapter 5. And, if you did Excursion 5-1, you found out the same thing about iodine.
Suppose you were to keep on testing things. you'd
find that hundreds of substances contain these atoms.
But you can get only copper atoms from pure copper.
And you can get only iodine atoms from pure iodine.
This is true no matter how hard you try.
Scientists have done a lot of this kind of testing.
They have studied many thousands of substances.
They have been able to identify only about one hundred materials that are pure. That is, materials they
could only get one substance from. These hundred
basic substances are called elements. Copper and iodine are two of these elements.
w
Every substance contains one or more of these
known elements. This includes trees, dogs, bananas,
frogs, rocks, cars, books, and, yes, even people. In
fact, every kind of matter known is made upbf one
or more elements.
Each element is made of only one kind of atom.
And the atoms of each element are different from
those of any of the other elements.
91
The names of the known kinds of atoms (elements)
are given in Table I in Technique 6, ..Chemical Ele_
ments and Their Symbols." Take a quick look at that
table now. You have probably heard of many of the
elements listed. Notice that each element has a short_
hand symbol. Note also that many of the symbols
have both capital and lowercase letters. The first letter in every symbol is always capitalized. If there is
a second letter, it is never capitalized.
Table 6-1
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6-1. Is the symbol for each element made up of
?
the first two
letters of the element's name?
n 6-2. Do any two elements have the same symbol?
fl6-3. What are the symbols for chlorine,
silver, and lead?
.
CHAPTER 6
copper,
Few scientists bother to rearn the symbols for all
the elements. Most learn the symbols ior a few com_
mon elements and look up the rest when needed.
Table 6-l lists the symbols for the elernents you will
most likely see. Take a few minutes to look over
them. Work with a partner or at home if you like.
The symbols for some elements are not at all like
the elements'names. For example, look at the sym_
bols for lead (Pb) and iron (Fel Why some of these
names and symbols are used is explained in Excur_
sion 6-1, "What's in a Name?,, you will find out what
some elements were named for_
Only about one hundred kinds of atoms account
for all the different kinds of matter in the world. Does
this statement really seem reasonable? It does only
if one hundred atoms can combine in a lot of ways.
D 6-4. Suppose you had four different atoms. How
many different ways do you think those four atoms
could be combined?
You can check your answer to question 6-4 by
using nuts and bolts. You will pretend the nuts and
bolts are different kinds of atoms. And you will find
out how many combinations of nut atoms and bolt
atgms are possible. To keep the problem simple, you
wili work with only four kinds of atoms. you will
work with two kinds of nuts and two kinds of bolts.
Square nut
Hex nut
Short bolt
A MATTER-MAKING
GAME
Well, you're ready to begin. Find a classmate who
rs at this same point i n the book. Ask your classmate
to be yo.r, opptnent in
to
in a contest. The object of
contest is to see who can make more different combi
nations using the nut and bolt
th;
atoms.
?OUAW
F AUfgf t{ATg
DrBtcTtoNs
CHAPTER
6
93
[ 6-5. How many different kinds of atoms are represented by the nuts and bolts?
tl
6-6. How many different elements are represented
by the nuts and bolts?
The contest will have three rounds.
Here are the game rules:
GAME RULES
1. To be counted as a combination, at least two
atoms (nuts and bolts) must be held together by
the threads. For example:
2. No two combinations can have exactly the same
kind and number of nuts and bolts.
3. Once a combination is made, draw it and take
it apart to make another. But you must be able
to connect any combination you have drawn.
4. Make your drawings like the ones shown in
Figure 6-1.
Figure6-1
Bmffi
5. The winner of a round will be the person who
has drawn more combinations in ihe Record
Book.
CHAPTER
All right, are you and your opponent ready to start?
*Round
one will
6
last 5 minutes. Remember, you may
use only 2 short-bolt atoms and 4 square_nut atoms.
li!'iir::.
ROUND
I
COMBINATIONS:
D 6-7. How many different combinations did you
make during Round l?
NUTS AND BOLTS-ROUND 2
Now for Round 2. This time you and your opponent will each need 2 short-bolt atoms, 4 square-nut
atoms, and 4 hex-nut atoms. The rules for playing
and winning are the same as they were in Round L
But in Round 2yoa will have l0 minutes. Remember
to make a simple drawing in your Record Book of
each combination you make. Ready . . . start!
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1.,,-.:
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6-10. How many different combinations did you
make in Round 2?
@
@
@
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THE BATTLE ROYAL
Okay, now for the third and last round. This will
be the battle
combination-makins conThe rules for this round are the
same as befbre. But the time limit is 15 minutes.
Everything ready? Then get started!
_ (Use your pencil to darken the heads of the long
bolts in your drawings. This will help you tell long
from short.)
@@@@@
@@@@@
96
CHAPTER 6
1;
:i
..,:'
,4
n
6-13. How many different combinations did you
make in Round 3?
You can sure make a lot of combinations out of
a few nut and bolt atoms! The third round should
certainly have convinced you of this. But maybe you
had already realized it after the first two rounds. As
a matter of fact, Round 3 could go on for a much
longer time. And, if it went on, you'd find many more
combinations.
It appears that a few kinds of basic building blocks
(atoms) may be all that is needed to produce man
combinations.
[
6-16. How does this support the idea that about
one hundred atoms make up every kind of matter?
Drawing nut-and-bolt pictures can be tiresome and
time-colsuming. There should be an easier way of
describing the combinations you've made. And tirere
is. It requires using a kind of shorthand.
SI$,IPLIFYING WITH SHORTHAND
Suppose you wanted to describe to a classmate one
of your combinations in Round l. This combination
is I square nut ihreaded onto I short bolt.
X 6-17. Draw a picture description of this combination in your Record Book.
[6-18.
Describe the combination
in words.
in question
6-17
CHAPTER 6
Now suppose you let Bo be shorthand for a short
bolt. Suppose you let Sq be shorthand for a square
nut.
E 6-19. Use these shorthand
symbols to describe the
combination in question 6-17.
n 6-20. Describe in your Record Book the following
combinations of short bolts and square nuts. Use the
same symbols as in question 6-19.
Your answer to question 6-19 should have been
BoSq or SqBo. You may have answered question
6-20-a in one of several ways, such as BoSqSq or
SqSqBo.
A simple way to use the symbols is to write BoSqr.
The 2 is called a subscript. It means that two Sq's
are combined with one Bo.
[
6-21. BorSq is a good description of the combination shown in question 6-20-b. What does the subscript 2 mean?
#
But how about the long bolts and hex nuts? Describe them by using shorthand, too. Let Bl stand for
long bolt (bolt long) and Hx for a hex nut.
Effi ,"
98
CHAPTER
6
@",.
t&*::+,ri
-a:
J6-22. Write a shorthand symbol to describe this
combination.
6-23. In the first column of Tabl e 6_2, draw pic_
tures of three different nut-and-bolt combinations. In
the next column, write a symbol to describe each
n
picture. (Don't use the combinations already
dis_
cussed.)
Sets
of symbols like BoSq, BoSq2, and BorSq
are
called formulas. A symbol represents oo, Ein^d of
atom. Remember, each element has its own symbol.
A formula represents a combination of more tian one
kind of atom- You can learn more about formulas by
doing Excursion 6-3, "Writing Shorthand Formulas.i,
Consider all the kinds of matter in the world. It's
hard to believe there are only about one hundrecr
kinds of atoms. But, as you've i"en, a very few atom/
are needed to form a lot of combinations. ontu J"
hundred atoms make up all kinds of matter.'T1,at
statement isn't so unbelievable if you assu
that
each combination is a different kind of marr
And
that is exactly what scientists assume.
CHAPTER 6