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Transcript
Catalog No. AP6440
Publication No. 6440
Naming Atoms — Elements, Ions and Isotopes
Student Activity Kit
Introduction
Use this simple and straightforward activity to help students understand the basics of a fundamental atomic concept, the
nucleus and its particles.
Concepts
s !TOM
s !TOMICNUMBER
s )SOTOPE
s )ON
Background
-ATTERISDEFINEDASANYSUBSTANCETHATHASMASSANDOCCUPIESAVOLUME!LLMATTERISEITHERAPUREELEMENTORACOMBINAtion of elements. Elements are matter that cannot be separated by chemical or physical means. Each element has its own unique
properties, such as melting point, density, and the way it reacts chemically. There are 90 elements that are naturally occurring. The
SMALLESTPARTOFANELEMENTTHATSTILLHASTHESESAMEPROPERTIESISCALLANATOM!LLATOMSAREMADEUPOFTHREETYPESOFPARTICLES
protons, neutrons, and electrons. The number of protons in an atom is called its atomic number. Every atom of each element has
exactly this number of protons.
Two of these three particles possess
electrical charge. The proton has a positive (+) charge, the electron has a negative (–) charge, and the neutron has no
ELECTRICAL CHARGE!N ATOM ALWAYS HAS
equal numbers of the positively charged
protons and the negatively charged electrons, giving the atom zero electrical
charge.
This neutral atom
has two electrons
in the electron cloud.
The electrons are very mobile and
can range from the center of the atom to
its outer edge. The best model that represents the electrons and their movement is
the electron cloud model. (See Figure 1.)
Protons and neutrons are always together
in the center, or nucleus, of the atom. (See
Figure 1.) The size of the nucleus is very Electron cloud
small and very compact when compared
to the size of the atom itself. In fact, as a
comparison if the nucleus were the size of
a golf ball, the atom’s outer edge would
be 23⁄4MILESAWAY!MODELOFANATOMIS
shown in Figure 1.
Nucleus
Neutron
++
Proton
Proton
Neutron
Figure 1. %LECTRON#LOUD-ODELOFTHE!TOM
CHEM-FAX!. . .makes science teaching easier.
IN6440
081012
Though electrons have the same, but opposite, charge as that of protons, their mass is extremely small compared to the protons and neutrons, which are approximately of equal mass. The mass of the atom is therefore determined by adding together the
masses of the protons and neutrons. The total number of protons and neutrons in an atom is called its atomic mass number.
When two atoms have the same number of protons, but different numbers of neutrons, they are called isotopes. Since isotopes
have the same number of protons, they are the same element and are identical in the ways they react. For example, atoms with
17 protons are called chlorine atoms. There are two isotopes of chlorine. One isotope has 17 protons and 18 neutrons. Its atomic
number is 17 (chlorine) and its atomic mass number is 35. The isotope is written as the element name, followed by the atomic
mass number. This isotope of chlorine is written chlorine–35. The other isotope of chlorine has 17 protons and 20 neutrons and is
written chlorine-37.
!LLTHEELEMENTSAREARRANGEDINACHARTCALLEDTHEPERIODICTABLE4HEELEMENTSARELISTEDINORDEROFINCREASINGATOMICNUMber, from left to right and top to bottom. Each element is enclosed in a box in the periodic table. The box typically contains the
element name, its one- or two-letter symbol and its atomic number (Figure 2).
!TOMICNUMBER
15
B
Symbol
Boron
Name
Figure 2.
To determine the element name of an atom, count the number of protons and look for this atomic number on the periodic
table.
In chemical reactions, atoms tend to gain or lose their electrons. If an atom loses or gains electrons and now has an unequal
number of protons and electrons, it is called an ion. If an atom contains 17 protons, 18 neutrons, and 18 electrons, then the atom is
a chloride ion. Ions are written using the element symbol, with the net number of electrons gained or lost at the top and right of the
SYMBOL)FTHEIONHASLOSTELECTRONSASIGNISPUTAFTERTHENUMBERIFTHEIONHASGAINEDELECTRONSAnSIGNISUSED)FTHEIONHAS
lost or gained only one electron, the number 1 is omitted from the ion symbol. The chloride ion, with one extra electron, is written:
Cl–
If an atom has 20 protons and 18 electrons and the atom has lost two electrons, then the ion is a calcium atom (atomic number
20) and the electrical charge is 2+ (20 – 18 = 2). The ion is written as:
Ca2+
Pre-Lab Questions (Look up elements on the periodic table on page 5.)
1. What is the element name for the following atoms.
a. 6 protons, 6 neutrons, and 6 electrons.
b. 18 protons, 20 neutrons, and 18 electrons.
c. 3 protons, 4 neutrons, and 3 electrons.
–2–
IN6440
Ú&LINN3CIENTIFIC)NC!LL2IGHTS2ESERVED2EPRODUCTIONPERMISSIONISGRANTEDONLYTOSCIENCETEACHERSWHOHAVEPURCHASED.AMING!TOMS#ATALOG.O!0FROM&LINN3CIENTIFIC)NC
No part of this material may be reproduced or transmitted in any form or by any means, electronic or mechanical, including, but not limited to photocopy, recording, or any information storage and
retrieval system, without permission in writing from Flinn Scientific, Inc.
2. Write the isotope name for the following atoms.
a. 8 protons, 8 neutrons, and 8 electrons.
b. 15 protons, 16 neutrons, and 15 electrons.
c. 30 protons, 36 neutrons, and 30 electrons.
!NATOMHASPROTONSNEUTRONSANDELECTRONSASECONDATOMHASPROTONSNEUTRONSANDELECTRONSANDA
third atom has 23 protons, 27 neutrons, and 18 electrons.
a. What is the name and symbol of the element?
b. What is the atomic mass number of each atom?
c. What is charge on each atom?
d. Write the ion.
4. Write the ions for the following atoms.
a. 5 protons, 6 neutrons, and 2 electrons.
b. 37 protons, 48 neutrons, and 36 electrons.
c. 16 protons, 16 neutrons, and 18 electrons.
Safety Precautions
The materials used in this activity are considered nonhazardous. Follow all standard laboratory safety practices.
Procedure
!TTHELABBENCHESAREBAGSLABELED!n2%ACHBAGCONTAINSVARIOUSAMOUNTSOFBLACKANDBLUEMARBLESWITHANUMBER
written on the outside of the bag. The black marbles represent protons, the blue marbles neutrons, and the written number
represents the total number of electrons.
2. For each bag, record the number of protons, neutrons, and electrons in the Data Table.
3. Using these values and the periodic chart, deduce the information needed to complete the Data Table for each bag. If the
atom is an ion, write its symbol in the “Ion Symbol” column.
–3–
IN6440
Ú&LINN3CIENTIFIC)NC!LL2IGHTS2ESERVED2EPRODUCTIONPERMISSIONISGRANTEDONLYTOSCIENCETEACHERSWHOHAVEPURCHASED.AMING!TOMS#ATALOG.O!0FROM&LINN3CIENTIFIC)NC
No part of this material may be reproduced or transmitted in any form or by any means, electronic or mechanical, including, but not limited to photocopy, recording, or any information storage and
retrieval system, without permission in writing from Flinn Scientific, Inc.
Name: ___________________________________
Data Table
Bag
# of
Protons
# of
Neutrons
Mass
Number
Element
# of
Electrons
Element
Symbol
Ion
Symbol
Isotope
Symbol
# of
Protons
# of
Neutrons
Mass
Number
Element
# of
Electrons
Element
Symbol
Ion
Symbol
Isotope
Symbol
# of
Protons
# of
Neutrons
Mass
Number
Element
# of
Electrons
Element
Symbol
Ion
Symbol
Isotope
Symbol
!
B
C
D
E
F
Bag
G
H
I
J
K
L
Bag
M
N
O
P
Q
2
–4–
IN6440
Ú&LINN3CIENTIFIC)NC!LL2IGHTS2ESERVED2EPRODUCTIONPERMISSIONISGRANTEDONLYTOSCIENCETEACHERSWHOHAVEPURCHASED.AMING!TOMS#ATALOG.O!0FROM&LINN3CIENTIFIC)NC
No part of this material may be reproduced or transmitted in any form or by any means, electronic or mechanical, including, but not limited to photocopy, recording, or any information storage and
retrieval system, without permission in writing from Flinn Scientific, Inc.
Ú&LINN3CIENTIFIC)NC!LL2IGHTS2ESERVED2EPRODUCTIONPERMISSIONISGRANTEDONLYTOSCIENCETEACHERSWHOHAVEPURCHASED.AMING!TOMS#ATALOG.O!0FROM&LINN3CIENTIFIC)NC
No part of this material may be reproduced or transmitted in any form or by any means, electronic or mechanical, including, but not limited to photocopy, recording, or any information storage and
retrieval system, without permission in writing from Flinn Scientific, Inc.
–5–
IN6440
H
2
4
1
3
12
9.012
20
19
21
3
IIIB
22
4
IVB
23
5
VB
24
6
VIB
25
7
VIIB
26
8
27
9
VIIIB
28
10
29
11
IB
30
12
IIB
B
C
12.01
14
6
14
IVA
31
26.98
32
28.09
Al Si
13
10.81
5
13
IIIA
P
33
30.97
10
9
19.00
17
20.18
18
F Ne
18
4.003
VIIIA
17
VIIA
He
2
34
32.07
35
35.45
36
39.95
S Cl Ar
16.00
16
8
16
VIA
N O
14.01
15
7
15
VA
The Periodic Table of the Elements
40
39
38
56
55
88
87
(223)
Lithium
Li
#
#
Ac–Lr
89–103
★
La–Lu
57–71
88.91
© 2012 Flinn Scientific, Inc.
Name
Symbol
3
(226)
Fr Ra
137.3
132.9
Cs Ba
87.62
85.47
58
57
59
(271)
106
183.8
60
(272)
107
186.2
75
(98)
61
(270)
108
190.2
76
101.1
44
55.85
62
(276)
109
192.2
77
102.9
45
58.93
195.1
110
78
106.4
46
58.69
197.0
111
79
107.9
47
63.55
200.6
112
80
112.4
48
65.38
204.4
113
81
114.8
49
69.72
207.2
114
82
118.7
50
72.64
209.0
115
83
121.8
51
74.92
(209)
116
84
127.6
52
78.96
I
(210)
117
85
126.9
53
79.90
(222)
118
86
131.3
Xe
54
83.80
63
(281)
64
(280)
65
(285)
66
(284)
67
(289)
68
(288)
(294)
71
(294)
70
(293)
69
140.1
90
140.9
91
144.2
92
(145)
93
150.4
94
152.0
95
157.3
96
158.9
97
162.5
98
164.9
99
167.3
100
168.9
101
173.0
102
175.0
103
(227)
232.0
231.0
238.0
(237)
(244)
(243)
(247)
(247)
(251)
(252)
(257)
(258)
(259)
(262)
Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
138.9
89
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
(268)
(267)
105
180.9
74
95.96
43
54.94
Rf Db Sg Bh Hs Mt Ds Rg Cn Uut Fl Uup Lv Uus Uuo
104
178.5
73
92.91
42
52.00
Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
72
91.22
41
50.94
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
47.87
44.96
40.08
Rb Sr Y
39.10
37
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
24.31
22.99
Na Mg
6.941
11
Li Be
IIA
IA
1.008
Atomic
Number
7
6
5
4
3
2
1
1