Chapter 3
Chemical
Foundations:
Elements, Atoms
and Ions
Section 3.1 – 3.3

3.1 The Elements

3.2 Symbols for the Elements

3.3 Dalton’s Atomic Theory
Copyright © by McDougal Littell. All rights reserved.
2
EXIT
Greek Attempts at Naming Elements

About 400 B.C. the Greeks proposed that all
matter was composed of four elements …
Fire
Earth
Water
Air
Copyright © by McDougal Littell. All rights reserved.
3
EXIT
2000 Years of History
Alchemy … the wish to turn cheap
metals into gold
Copyright © by McDougal Littell. All rights reserved.
4
EXIT
A Bright Spot
Robert Boyle
(1627 - 1691)



Known for his work with
gases
Emphasized the
importance of
experimentation.
Definition of an element:
something that couldn’t be
broken down into two or
more simpler substances.
Copyright © by McDougal Littell. All rights reserved.
5
EXIT
Elements Today

Approximately 112 known elements
 88 occur naturally
 Remainder are synthetically formed
 These ~100 elements make up the millions
of known compounds
Copyright © by McDougal Littell. All rights reserved.
6
EXIT
Table 3.1
Copyright © by McDougal Littell. All rights reserved.
7
EXIT
Top Ten
Copyright © by McDougal Littell. All rights reserved.
8
EXIT
Top Ten Comparison
Copyright © by McDougal Littell. All rights reserved.
9
EXIT
Table 3.3
Copyright © by McDougal Littell. All rights reserved.
10
EXIT
Names of Elements

From Greek, Latin, or German words …
– Latin …
“aurum” (shining dawn) … gold
“plumbum” (heavy) … lead
– Greek …
colors … chlorine (yellow) & iodine (purple)
smell … bromine (stench)
Copyright © by McDougal Littell. All rights reserved.
11
EXIT
Names of Elements

For the place where it was discovered …
Francium …
Germanium …
Californium …
Americium …
Copyright © by McDougal Littell. All rights reserved.
12
EXIT
Names of Elements

For famous scientists …
Einsteinium
Fermium
Nobelium
Rutherfordium
Bohrium
Copyright © by McDougal Littell. All rights reserved.
13
EXIT
Symbols of Elements

A shorthand way to name an element.
 Often composed of the first letter or first
two letters of an element …
Fluorine … F
Oxygen … O
Neon … Ne
Silicon … Si
Copyright © by McDougal Littell. All rights reserved.
14
EXIT
Symbols of Elements

An important rule …
If an elements symbol is two letters the first
is ALWAYS capitalized and the second is
ALWAYS lower case!
Cu = copper
CU = carbon and uranium
CuSO4
Copyright © by McDougal Littell. All rights reserved.
15
EXIT
Symbols of Elements

Sometimes the two letters in a symbol are
not the first two letters of the elements
name …
Zinc … Zn
Chlorine …Cl
Cadmium … Cd
Platinum … Pt
Copyright © by McDougal Littell. All rights reserved.
16
EXIT
Symbols of Elements

Sometimes the two letters in a symbol are
not the first two letters of the elements
name …sometimes they represent the
Greek, Latin, or German root …
Gold … Au
Lead … Pb
Sodium … Na
Iron … Fe
Copyright © by McDougal Littell. All rights reserved.
17
EXIT
18th Century Observations

Most natural materials are mixtures of pure
substances
 Pure substances are either elements or
combinations of elements called
compounds.
 A given compound always contains the
same proportions (by mass) of its elements.
Copyright © by McDougal Littell. All rights reserved.
18
EXIT
John Dalton
(1766 – 1844)
Dalton’s Atomic Theory
 Elements are made
of tiny particles
called atoms.
Copyright © by McDougal Littell. All rights reserved.
19
EXIT
John Dalton
(1766 – 1844)
Dalton’s Atomic Theory
 All atoms of a given
element are
identical.
Copyright © by McDougal Littell. All rights reserved.
20
EXIT
John Dalton
(1766 – 1844)
Dalton’s Atomic Theory
 The atoms of a given
element are different
from those of any
other element.
Copyright © by McDougal Littell. All rights reserved.
21
EXIT
John Dalton
(1766 – 1844)
Dalton’s Atomic Theory
 Atoms of one
element can combine
with atoms of other
elements to form
compounds. A
given compound
always has the same
relative numbers and
types of atoms.
Copyright © by McDougal Littell. All rights reserved.
22
EXIT
John Dalton
(1766 – 1844)
Dalton’s Atomic Theory
 Atoms are
indivisible in
chemical processes.
Atoms cannot be
created or destroyed,
they are only
rearranged.
Copyright © by McDougal Littell. All rights reserved.
23
EXIT
Dalton’s Model predicted these molecules!
Copyright © by McDougal Littell. All rights reserved.
24
EXIT
Section 3.1 – 3.3 Assignments
Read 3.1 – 3.3 (pp. 47 – 53)
 Focus Questions p. 53: 1-5

Copyright © by McDougal Littell. All rights reserved.
25
EXIT
Section 3.4 – 3.7

3.4 Formulas of Compounds

3.5 The Structure of the Atom

3.6 Intro. to the Modern Concept of Atomic
Structure

3.7 Isotopes
Copyright © by McDougal Littell. All rights reserved.
26
EXIT
Formulas of Compounds
A compound …
A compound is a distinct
substance that is composed of the atoms of
two or more elements chemically combined
and always contains exactly the same
relative masses of those elements.
Copyright © by McDougal Littell. All rights reserved.
27
EXIT
Formulas of Compounds
A formula …
A shorthand representation of the types of
atoms and the number of each type in each
unit (molecule) of a given compound.
Copyright © by McDougal Littell. All rights reserved.
28
EXIT
Formulas of Compounds
Rules for writing formulas
1. Each atom present is represented by its
element symbol.
2. The number of each type of atom is
indicated by a subscript written to the
right of the element symbol.
3. When only one atom of a given type is
present, the subscript 1 is not written.
Copyright © by McDougal Littell. All rights reserved.
29
EXIT
Formulas of Compounds
Carbon dioxide … (1 carbon atom chemically
bonded to 2 oxygen atoms)
CO2
Copyright © by McDougal Littell. All rights reserved.
30
EXIT
Formulas of Compounds
Baking Soda … (1 sodium atom chemically
bonded to 1 hydrogen atom, 1 carbon
atom, and 3 oxygen atoms)
NaHCO3
Copyright © by McDougal Littell. All rights reserved.
31
EXIT
Formulas of Compounds
Glucose … (6 carbon atoms with 12 hydrogen
atoms and 6 oxygen atoms)
C6H12O6
Copyright © by McDougal Littell. All rights reserved.
32
EXIT
Formulas of Compounds
Write these formulas …
 4 phosphorus atoms with 10 oxygen atoms

1 uranium atom with 6 fluorine atoms

1 aluminum atom with 3 chlorine atoms
Copyright © by McDougal Littell. All rights reserved.
33
EXIT
The Structure of the Atom
From 1808 (John Dalton) to almost 1900 not
much was known about the actual
structure of the atom.
 Does it contain smaller parts?
 What holds atoms together?
 How do atoms bond to other atoms?
 Is an atom uniform throughout?
Copyright © by McDougal Littell. All rights reserved.
34
EXIT
The Structure of the Atom
J.J. Thomson (1897)
Works with electricity,
metal plates, and gas
filled glass tubes.
Discovers the electron!
Copyright © by McDougal Littell. All rights reserved.
35
EXIT
Figure 3.7: Schematic of a cathode ray tube.
Copyright © by McDougal Littell. All rights reserved.
36
EXIT
Thomson’s Plum Pudding model of an atom.
Copyright © by McDougal Littell. All rights reserved.
37
EXIT
The Structure of the Atom
Ernest Rutherford (1910)


Gold foil
experiment!
Used heavy
positively charged
alpha particles
Copyright © by McDougal Littell. All rights reserved.
38
EXIT
Figure 3.5: Rutherford’s experiment.
Copyright © by McDougal Littell. All rights reserved.
39
EXIT
Figure 3.6: Results of foil experiment if Plum Pudding model had been correct.
Copyright © by McDougal Littell. All rights reserved.
40
EXIT
Figure 3.6: Actual Results.
Copyright © by McDougal Littell. All rights reserved.
41
EXIT
Rutherford’s Gold Foil Experiment
Results

Most alpha particles went straight through.
 Some alpha particles were deflected.
 A few alpha particles were reflected
backwards
“…it was like shooting a gun at a piece of
paper and having the bullet bounce back.”
(Rutherford)
Copyright © by McDougal Littell. All rights reserved.
42
EXIT
Rutherford’s Gold Foil Experiment
Conclusions

Atoms have a nucleus
 The nucleus has a positive charge
 The nucleus is small and very dense

By 1919 Rutherford predicts the existence
of the proton, a positively charged particle
in the nucleus. (same magnitude charge as
an electron, but opposite in charge)
Copyright © by McDougal Littell. All rights reserved.
43
EXIT
Other Atomic Discoveries

James Chadwick (1932)
The Neutron is found.
Slightly heavier than a proton but with no
charge.
Copyright © by McDougal Littell. All rights reserved.
44
EXIT
A nuclear atom viewed in cross section.
For comparison purposes
If the nucleus were the
size of a grape, the
electrons would be
about one mile away!
Copyright © by McDougal Littell. All rights reserved.
45
EXIT
The Mass and Charge of the Atomic Particles
Subatomic
Mass
Mass
Location
Particle
g
amu
in atom
Proton
1.67
1
nucleus
+1
p, p+, H+
~0
empty space
-1
e, e-
1
nucleus
0
n, n0
Charge Symbol
x 10-24
Electron
0.0009
x 10-24
Neutron
1.67
x 10-24
Copyright © by McDougal Littell. All rights reserved.
46
EXIT
Question
So if all atoms (of all elements)
are composed of the same particles, why do
different atoms have different chemical
properties?
Copyright © by McDougal Littell. All rights reserved.
47
EXIT
Answer
1.
Electrons … give most chemical
properties (will explore later)
2.
Protons … determine the element
3.
Neutrons … determine the isotope
Copyright © by McDougal Littell. All rights reserved.
48
EXIT
An Example: Sodium
1.
2.
3.
All sodium atoms have 11 protons
Because atoms are electrically neutral,
each sodium atom also has 11 electrons
But what about neutrons …
12 OR 13
Copyright © by McDougal Littell. All rights reserved.
49
EXIT
Isotopes of Sodium
Isotopes: atoms of the same element (same number of
protons) with different numbers of neutrons.
Copyright © by McDougal Littell. All rights reserved.
50
EXIT
Isotopes
• Atomic Number
 Number of protons
Z
• Mass Number
 Protons + Neutrons
 Whole number
A
 Abundance = relative
amount found in a sample
EXIT
51
Isotopes

Cl-35 has a mass number = 35, 17 protons
and 18 neutrons (35 - 17)
35
17
Atomic Symbol
A = mass number
Z = atomic number
Cl
AX
Z
EXIT
52
Neon
Symbol
Percent
Number of Number of A, Mass Natural
Protons
Neutrons Number Abundance
Ne-20 or 20
10 Ne
10
10
20
90.48%
21 Ne
Ne-21 or 10
10
11
21
0.27%
Ne-22 or 22
10 Ne
10
12
22
9.25%
EXIT
53
Practice - Complete the following table
Atomic Mass Number Number Number
Number Number
of
of
of
Protons Electrons Neutrons
Calcium-40
Carbon-13
Aluminum-27+3
54
EXIT
Practice - Complete the following table
Calcium-40
Atomic Mass Number Number Number
Number Number
of
of
of
Protons Electrons Neutrons
20
40
20
20
20
Carbon-13
6
13
6
6
7
Aluminum-27+3
13
27
13
10
14
55
EXIT
Mass Number is Not the Same
as Atomic Mass

the atomic mass is an experimental number
determined from all naturally occurring
isotopes
 the mass number refers to the number of
protons + neutrons in one isotope
– natural or man-made
EXIT
56
Calculating Atomic Mass
Gallium has two naturally occurring isotopes: Ga-69 with mass
68.9256 amu and a natural abundance of 60.11% and Ga-71 with
mass 70.9247 amu and a natural abundance of 39.89%. Calculate
the atomic mass of gallium.
Solution:
1)
Convert the percent natural abundance into decimal form.
Ga-69  0.6011
Ga-71  0.3989
2)
Determine the Formula to Use
Atomic Mass = (abundance1)∙(mass1) + (abundance2)∙(mass2) + ...
2)
Apply the Formula:
Atomic Mass = 0.6011 (68.9256 amu) + 0.3989 (70.9247 amu)
= 69.72 amu
EXIT
57
Section 3.4 – 3.7 Assignments

Read 3.4 – 3.7 (pp. 54 – 63)

Focus Questions p. 63: 1-5
Copyright © by McDougal Littell. All rights reserved.
58
EXIT
Section 3.8 – 3.10

3.8 Intro. to the Periodic Table

3.9 Natural States of the Elements

3.10 Ions
Copyright © by McDougal Littell. All rights reserved.
59
EXIT
The Periodic Table

Each box represents one element

Minimally each box must contain …
– Symbol
– Atomic Number

Most contain much more information!
Copyright © by McDougal Littell. All rights reserved.
60
EXIT
The Periodic Table

The elements are arranged left to right and
top to bottom according to their atomic
number (Mendeleev, 1869)

When arranged in this fashion, elements
with similar properties repeat in a regular
pattern … “periodic” table
Copyright © by McDougal Littell. All rights reserved.
61
EXIT
The Periodic Table
Columns … called “groups” or “families”
contain elements with similar properties.
 Important groups to know include …

–
–
–
–
1A
2A
7A
8A
Alkali metals
Alkali earth metals
Halogens
Nobel gases (inert, nonreactive)
– Transition metals (varying properties)
Copyright © by McDougal Littell. All rights reserved.
62
EXIT
Figure 3.11: The periodic table.
Copyright © by McDougal Littell. All rights reserved.
63
EXIT
= Alkali Metals
= Halogens
= Alkali Earth Metals
= Lanthanides
= Noble Gases
= Actinides
= Transition Metals
EXIT
64
Important Groups – IA, Alkali Metals

hydrogen usually placed here,
though it doesn’t belong
lithium

soft, low melting points, low density

flame tests  Li = red, Na = yellow, sodium
K = violet

very reactive, never find
uncombined in nature

react with water to form basic
(alkaline) solutions and H2
2 Na + 2 H2O  2 NaOH +
H2

potassium
rubidium
cesium
releases a lot of heat
EXIT
65
Important Groups – IIA, Alkali Earth Metals

harder, higher melting, and denser
than alkali metals

flame tests  Ca = red, Sr = red,
Ba = yellow-green

reactive, but less than
corresponding alkali metal
beryllium
magnesium
calcium

oxides are basic = alkaline earth

reactivity with water to form H2,
Be = none; Mg = steam; Ca, Sr, Ba
= cold water

strontium
barium
EXIT
66
Important Groups – VIIA, Halogens

Nonmetals

F2 & Cl2 gases; Br2 liquid; I2 solid

all diatomic
fluorine

very reactive
chlorine

Cl2, Br2 react slowly with water
Br2 + H2O  HBr + HOBr
bromine
iodine

react with metals to form ionic
compounds

HX all acids
– HF weak < HCl < HBr < HI
EXIT
67
Important Groups – VIIIA, Noble Gases

all gases at room
temperature,
– very low melting and
boiling points

very unreactive, practically
inert

very hard to remove
electron from or give an
electron to
EXIT
68
Figure 3.12: Elements classified as metals and nonmetals.
Metals:
1.
Conduct heat & electricity
2.
Malleable
3.
Ductile
4.
Lustrous
Copyright © by McDougal Littell. All rights reserved.
69
EXIT
Figure 3.12: Elements classified as metals and nonmetals.
Metals:
Nonmetals:
1.
Conduct heat & electricity
2.
Malleable
3.
Ductile
4.
Lustrous
Copyright © by McDougal Littell. All rights reserved.
1.
Insulators
2.
Brittle
3.
Often gases or liquids
70
EXIT
Figure 3.12: Elements classified as metals and nonmetals.
Metals:
Nonmetals:
1.
Conduct heat & electricity
2.
Malleable
3.
Ductile
4.
Lustrous
Metalloids (semimetals)
Metal & nonmetal properties
Copyright © by McDougal Littell. All rights reserved.
1.
Insulators
2.
Brittle
3.
Often gases or liquids
71
EXIT
Naturally Occurring Elements

Most elements are
found naturally
combined with other
elements.

Some exceptions …
– Au, Ag, Pt
– Nobel gases
Copyright © by McDougal Littell. All rights reserved.
72
EXIT
Figure 3.13: A collection of argon atoms.
Copyright © by McDougal Littell. All rights reserved.
73
EXIT
Naturally Occurring Elements

Another important group …doesn’t exist as
single atoms …but as two atoms joined
together.
Diatomic Gases
Copyright © by McDougal Littell. All rights reserved.
74
EXIT
Figure 3.14: Nitrogen gas contains NXN molecules.
Copyright © by McDougal Littell. All rights reserved.
75
EXIT
Figure 3.14: Oxygen gas contains OXO molecules.
Copyright © by McDougal Littell. All rights reserved.
76
EXIT
“Silly Seven”
Copyright © by McDougal Littell. All rights reserved.
77
EXIT
Figure 3.15: The decomposition of two water molecules.
Copyright © by McDougal Littell. All rights reserved.
78
EXIT
Ions and the Periodic Table
Read 3.8 – 3.10
(pp. 63 – 74)
Figure 3.19: The ions formed by selected members of groups 1, 2, 3, 6, and 7.
Copyright © by McDougal Littell. All rights reserved.
81
EXIT
Section 3.11
Compounds that Contain Ions
Figure 3.20: Pure water does not conduct a current.
Copyright © by McDougal Littell. All rights reserved.
83
EXIT
Figure 3.20: Water containing dissolved salt conducts a current.
Copyright © by McDougal Littell. All rights reserved.
84
EXIT
Ions

Atoms acquire a charge by gaining or losing electrons
– not protons!!

Ion Charge = # protons – # electrons

ions with a + charge are called cations
– more protons than electrons
– form by losing electrons

ions with a – charge are called anions
– more electrons than protons
– form by gaining electrons
EXIT
85
Atomic Structures of Ions

Metals form cations

For each positive charge the ion has 1 less electron than the
neutral atom
– Na atom = 11 p+ and 11 e-, Na+ ion = 11 p+ and 10 e– Ca atom = 20 p+ and 20 e-, Ca2+ ion = 20 p+ and 18 e-

Cations are named the same as the metal
sodium
Na  Na+ + 1ecalcium
Ca  Ca2+ + 2e-

sodium ion
calcium ion
The charge on a cation can be determined from the Group
number on the Periodic Table
– Group 1A  +1, Group 2A  +2, (Al, Ga, In)  +3
EXIT
86
Atomic Structures of Ions

Nonmetals form anions

For each negative charge the ion has 1 more electron than the
neutral atom
– F = 9 e-, F- = 10 e– P = 15 e-, P3- = 18 e-

Anions are named by changing the ending of the name to -ide
fluorine
F + 1e-  Ffluoride ion
oxygen
O + 2e-  O2oxide ion

The charge on an anion can be determined from the Group
number on the Periodic Table
– Group 7A  -1, Group 6A  -2
EXIT
87
Atomic Structures of Ions
+
-
p
e
-1
17
18
+1
19
18
-2
16
18
+2
38
36
Ion
Cl
K
S
Sr
EXIT
88
IA
IIA
IIIA
Li+1 Be+2
Na+1 Mg+2
K+1 Ca+2
Rb+1 Sr+2
Al+3
Zn+2 Ga+3
Ag+1 Cd+2 In+3
VA VIA VIIA
N-3 O-2
F-1
P-3 S-2
Cl-1
As-3 Se-2 Br-1
Te-2 I-1
Cs+1 Ba+2
EXIT
89