6.1 Atoms and Elements
Think about how many words are in an English dictionary. All
these words are formed from only the 26 letters in our alphabet.
In a similar way, three particles form the many kinds of atoms
that make up everything around you.
Parts of an Atom
Each atom contains three kinds of particles: protons, neutrons,
and electrons. A proton is positively charged. A neutron has no
charge and is similar in mass to a proton. Both protons and
neutrons are found in the tiny central part of an atom called the
nucleus. An electron is negatively charged and has much less
mass compared to a proton and a neutron. Electrons orbit the
nucleus, much like planets orbit the Sun.
BEGIN SIDEBAR:
- proton: a positively charged particle in an atom
- neutron: a particle in an atom that has no electrical charge
- electron: a negatively charged particle found in an orbit
outside the nucleus of an atom
END SIDEBAR.
The numbers of protons and electrons in an atom are equal. The
positive charges of the protons and negative charges of the
electrons cancel each other out, making each atom neutral
(neither positive nor negative). Table 1 summarizes some
important information about each kind of particle found in an
atom. We use atomic models to show the number of each kind of
subatomic particle and where it is located (Figure 1).
BEGIN FIGURE CAPTION:
Figure 1 This model of a fluorine atom shows that it has 9
protons (9p+), 9 electrons (blue dots), and 10 neutrons (10n0).
There are 2 electrons in the first orbit and 7 electrons in the
second orbit.
BEGIN PRODUCER’S NOTE:
Figure not reproduced.
END PRODUCER’S NOTE.
END FIGURE CAPTION.
Electron Orbits
As shown in Figure 1, electrons are located in orbits outside the
nucleus of the atom. The first orbit can hold 2 electrons. The
second orbit can hold up to 8 electrons. The third orbit can also
hold up to 8 electrons.
Table 1 Particles in an Atom
Particle name Charge
proton
+
neutron
neutral
electron
-
Location
nucleus
nucleus
orbits
Symbol
p+
n0
e-
PRINT PAGE 211
The Importance of Organization
If we put things in a logical order, or organize them, it is easier to
find those things later. Imagine looking for items in a grocery
store where items are arranged in alphabetical order. Pickles
would be next to Popsicles and lettuce would be next to light
bulbs! Pickles do not need to be frozen and lettuce wilts if it is not
stored in a cool, damp place, so a different organizing system is
needed. Putting groceries in order by the type of item and the
type of storage they need makes more sense (Figure 2).
BEGIN FIGURE CAPTION:
Figure 2 Items in a grocery store are placed in aisles according
to shared properties.
BEGIN PRODUCER’S NOTE:
Figure not reproduced.
END PRODUCER’S NOTE.
END FIGURE CAPTION.
Organizing the Elements
All matter is made up of elements. An element is a substance
that cannot be broken down into simpler substances. Gold,
copper, and oxygen are common examples of elements. Each
element is made up of only one kind of atom. This is why gold
has exactly the same properties no matter where in the world it is
mined. Gold and copper have different properties because they
are made of different kinds of atoms.
BEGIN SIDEBAR:
- element: a pure substance that cannot be broken down into
simpler substances, either physically or chemically
END SIDEBAR.
You may recall that scientists often record data in tables. A table
helps organize data so people can make sense of it. All the
elements are arranged in the periodic table so that elements
with similar properties are grouped together.
BEGIN SIDEBAR:
- periodic table: the table that lists all the known elements in
rows and columns based on patterns of similar properties
END SIDEBAR.
PRINT PAGE 212
The Modern Periodic Table
Elements in the periodic table are arranged in order of the
number of protons their atoms have (Figure 3). The number of
protons is called the element's atomic number. Each element
has a different atomic number (Figure 4).
BEGIN SIDEBAR:
- atomic number: the number of protons in an atom of an
element; each element has a different atomic number
END SIDEBAR.
Figure 3 The elements of the periodic table are arranged in rows (also
called periods) and columns. Each group of elements has similar
properties.
1
2
3
4
5
6
1
H
Li
*
Na
*
K*
2
Be
*
Mg
*
Ca
*
Rb Sr
* *
Cs Ba
* *
Period
(ARROW
POINTING
RIGHT)
Group of
Chemical
Family
(ARROW
POINTING
DOWN)
3
4
5
6
7
8
9
10
11
12
Sc *
Ti
*
Zr
*
Hf
*
V*
Cr *
Mn
*
Tc
*
Re
*
Fe
*
Ru
*
Os
*
Co
*
Rh
*
Ir
*
Ni
*
Pd
*
Pt
*
Cu
*
Ag
*
Au
*
Zn
*
Cd
*
Hg
*
Y*
La *
Nb
Mo *
*
Ta * W *
7
Fr
*
Ce
*
Th
*
Pr
*
Pa
*
Ra Ac *
*
Nd
*
U
*
Pm
*
Np
*
Rf Db
* *
Sm
*
Pu
*
Eu
*
Am
*
Gd
*
Cm
*
Sg *
Tb
*
Bk
*
By
*
Cf
*
Ho
*
Es
*
Bh
*
Hs
*
Mt
*
Ds
*
Er
*
Fm
*
Tm
*
Md
*
Yb
*
No
*
Lu
*
Lr
*
BEGIN PRODUCER’S NOTE:
The second table is located between La, Hf, Ac and Rf in the first
table.
END PRODUCER’S NOTE.
Figure 4 The atomic number is at the top left-hand corner of each element
on the periodic table.
29
Cu
copper
63.55
- Each element in the periodic table has its own box. In the box is
the element's chemical symbol, name, and atomic number.
- The first letter of every chemical symbol is a capital letter (e.g.,
N for nitrogen). If there is a second letter, it is lowercase (e.g.,
Na for sodium).
- Each row in the periodic table is called a period. The properties
of the elements that are in the same period can be very different.
BEGIN SIDEBAR:
- period: a horizontal row in the periodic table of elements
END SIDEBAR.
- The elements are also placed in columns according to how their
electrons are arranged. Each column in the periodic table is called
Rg
*
Uub
a group or chemical family. Elements in the same group have
similar properties. Within each group, all atoms have the same
number of electrons in their outermost orbits.
BEGIN SIDEBAR:
- group or chemical family: a vertical column in the periodic
table of elements
END SIDEBAR.
-Most elements are either metals (blue boxes) or non-metals
(pink boxes). They are separated by a dark line that looks like a
staircase. Hydrogen is the only exception. Elements along the
staircase have properties in between those of metals and nonmetals. These elements are called metalloids (green boxes).
BEGIN PRODUCER’S NOTE:
The metals are represent by *, the non-metals by ** and the
metalloids by ***.
END PRODUCER’S NOTE.
PRINT PAGE 213
Chemical Families
Group 1
The structure of atoms explains why elements have similarities
and differences. The alkali metal group consists of the elements
below hydrogen in the first column of the periodic table, starting
with lithium. Lithium (Li) has one outer electron, as do sodium
(Na), potassium (K), and other elements in the group. When an
alkali metal reacts, each of its atoms loses the single electron in
its outermost orbit. The alkali metals have similar reactions
because they all have one electron in their outermost orbits
(Figure 5). However, the reactivity of alkali metals increases
from the top of Group 1 to the bottom.
BEGIN FIGURE CAPTION:
Figure 5 These elements react in a similar way because each
atom has one electron in its outermost electron orbit.
BEGIN PRODUCER’S NOTE:
Figure not reproduced.
END PRODUCER’S NOTE.
END FIGURE CAPTION.
Group 2
The elements in Group 2 are the alkaline earth metals. Beryllium
(Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium, and
radium (Ra) all have two electrons in their outermost orbits. The
reactivity of Group 2 metals also increases from the top of the
group to the bottom.
Periodic Trends
Elements in the same group or family always share some
chemical and physical properties. Elements in the same period
also show some trends in their reactivity. For example, Group 1
alkali metals are more reactive than the elements in Group 2.
That means that sodium (Na) is more reactive than magnesium
(Mg), and potassium (K) is more reactive than calcium (Ca). The
elements in Group 17 halogens are more reactive than Group 16
elements in the same row. You will learn more about Group 17
and Group 18 in Section 6.4. The rows on the periodic table are
called periods because they show the repeating nature of these
trends in reactivity. The word "period" refers to cycles, such as
the classes that recur daily in your school schedule.
Figure 6, on the next page, shows properties and common uses
of the elements.
PRINT PAGE 214
Periodic Table of the Elements
symbols for descriptions (LINE POINTING DOWN)
# atomic number)
hydrogen
Xx (symbol of element)
BEGIN PRODUCER’S NOTE:
Picture not reproduced.
END PRODUCER’S NOTE.
example
BEGIN TEXTBOX:
Description
* solid
** liquid
*** gas
**** part of the human body
***** never found in nature
****** radioactive
******* magnetic
BEGIN PRODUCER’S NOTE:
The symbols have been replaced by *.
END PRODUCER’S NOTE.
END TEXTBOX.
BEGIN PRODUCER’S NOTE:
The pictures in the Periodic Table of Elements are not reproduced.
END PRODUCER’S NOTE.
1
H
***
****
hydrogen
rocket fuel
ΔΔΔΔ
3
Li
*
lithium
batteries
Δ
11 Na
*
****
sodium
table salt
Δ
19
K
*
****
potassium
fertilizer
Δ
37
Rb
*
rubidium
global
positioning
system
(Gps)
Δ
55
Cs
*
cesium
global
2
4
Be
*
beryllium
emeralds
Δ
12
Mg
*
magnesium
upset
stomach
remedy
Δ
20
Ca
*
***
calcium
bones
Δ
3
4
5
6
21
Sc
*
scandium
racing bikes
Δ
22
Ti
*
titanium
replacement
joints
Δ
23
V
*
vanadium
nuts and
bolts
Δ
24
*
chro
stai
stee
Δ
38
Sr
*
strontium
flares
Δ
39
Y
*
yttrium
cancer
treatment
Δ
40
Zr
*
zirconium
nuclear
reactors
Δ
41
Nb
*
niobium
maglev
trains
Δ
42
*
mol
drill
Δ
56
Ba
*
barium
contrast
57
La
*
lanthanum
carbon arc
72
Hf
*
hafnium
reactor
73
Ta
*
tantalum
cellphones
74
*
tung
ligh
positioning
system
(Gps)
Δ
87
Fr
*
******
francium
radioactive
Δ
agent for X- lamps
rays
Δ
Δ
control rods
Δ
Δ
88 Ra
*
******
radium
radioactive
Δ
104
Rf
******
*****
rutherfordium
no use
Δ
105
89
Ac
*
******
actinium
radioactive
medecine
Δ
filam
Δ
Db
******
*****
dubnium
no use
Δ
106
Sg
******
*****
seaborgium
no use
Δ
58
Ce
*
cerium
self-cleaning
ovens
Δ
90
Th
*
******
thorium
camera
lenses
Δ
59
Pr
*
praseodymium
coloured glass
Δ
60
Nd
*
neodymium
speakers
Δ
91
Pa
*
******
protactinium
radioactive
waste
Δ
92
U
*
******
uranium
nuclear
energy
Δ
107
Bh
******
*****
bohrium
no use
Δ
61
Pm
*
promethium
X-ray
machines
Δ
93
Np
*
******
neptunium
radioactive
waste
Δ
62 Sm
*
samarium
headphone
magnets
Δ
94
Pu
*
******
*****
plutonium
nuclear
weapons
Δ
BEGIN PRODUCER’S NOTE:
The second table is located between lanthanum, hafnium,
actinium and rutherfordium in the first table.
END PRODUCER’S NOTE.
Figure 6 The properties of elements determine their uses.
Δ metals
ΔΔ metalloids
ΔΔΔ nonmetals
ΔΔΔΔ hydrogen
BEGIN PRODUCER’S NOTE:
The colours code for the properties of the elements have been
replaced with Δ.
END PRODUCER’S NOTE.
PRINT PAGE 215
10
11
12
13
14
5
B
*
boron
sports
equipment
ΔΔ
6
C
*
****
carbon
diamonds
ΔΔΔ
13
Al
*
aluminum
cans and foil
14
Si
*
silicon
computer
Δ
chips
ΔΔ
28 Ni
*
*******
nickel
stainless steel
Δ
29
Cu
*
cooper
water pipes
Δ
30
Zn
*
zinc
galvanized
steel
Δ
31
Ga
*
gallium
light-emitting
diodes (LEDs)
Δ
32
Ge
*
germanium
solar panels
ΔΔ
46
Pd
*
palladium
dental crowns
Δ
47
Ag
*
silver
jewellery
Δ
48
Cd
*
cadmium
Ni-Cd
batteries
Δ
50
Sn
*
tin
bronze
Δ
78
Pt
*
platinum
jewellery
Δ
79
Au
*
gold
jewellery
Δ
80
Hg
**
mercury
dental
amalgams
Δ
49
In
*
indium
liquid crystal
displays
(LCDs)
Δ
81
Ti
*
thallium
ant killer and
rat poison
Δ
110 Ds
******
*****
darmstadtium
no use
Δ
111
Rg
******
*****
roentgenium
no use
Δ
112 Uub
******
*****
copernicium
no use
113
Uut
******
*****
ununtrium
no use
63
Eu
*
europium
luminous
paint
64
Gd
*
gadolinium
magnetic
resonance
65 Tb
*
terbium
laser
material
66
By
*
dysprosium
compact
discs
82
Pb
*
lead
radiation
shield for Xrays
Δ
114
Uuq
******
*****
ununquadium
no use
67 Ho
*
holmium
reactor
control rods
68
Er
*
erblum
colouran
in glasse
Δ
95
Am
*
******
*****
americium
smoke
detector
Δ
imaging
(MRIs)
Δ
96
Cm
*
******
*****
curium
energy
source for
the Mars
Rover
Δ
Δ
Δ
Δ
Δ
97
Bk
*
******
*****
berkelium
radioactive
waste
Δ
98
Cf
*
******
*****
californium
aircraft
safety check
Δ
99
Es
*
******
*****
einsteinium
no use
Δ
100 Fm
*
******
*****
fermium
no use
Δ
PRINT PAGE 216
BEGIN TEXTBOX:
TRY THIS FLAMING COLOURS
SKILLS HANDBOOK
3.B.5.-3.B.7., 3.B.9.
SKILLS: Performing, Observing, Analyzing, Communicating
Fireworks and sparklers give off colours when they are heated or
burned. You can heat substances that contain different metal
elements by holding samples of them in a flame (Figure 7). This
is called a flame test. The bright colours of light that result are
due to the structure of the metal atoms. Light is given off when
electrons of the atoms gain and then lose energy. The flame test
can be used to identify unknown metals in paint samples.
BEGIN TEXTBOX:
CAUTION: FLAME
BEGIN PRODUCER’S NOTE:
Representation of a hand not reproduced.
END PRODUCER’S NOTE.
Never heat anything without your teacher's permission. Always
wear eye protection when you are working with fire. Keep
yourself, and anything else that can burn, away from heat or
flames. Tie back long hair and loose clothing. Never reach across
a flame. Do not leave the flame unattended.
END TEXTBOX.
BEGIN FIGURE CAPTION:
Figure 7 The colour given off in a flame test can be used to
identify a substance.
BEGIN PRODUCER’S NOTE:
Figure not reproduced.
END PRODUCER’S NOTE.
END FIGURE CAPTION.
Equipment and Materials: eye protection; lab apron; plastic
vials; samples of metal salts; matches or striker; Bunsen burner;
retort stand and clamp; wire loops; distilled water
1. Put on your lab apron and eye protection.
2. Obtain a small sample of each salt provided as well as the wire
loop that goes with the sample.
3. Make a chart to record the names of your salt samples and the
colour of flame each produces.
4. Clamp the burner to the retort stand. Light your Bunsen
burner. Adjust the flame so that it is mostly blue.
5. Dip the end of the wire loop into the water and then into the
first sample. Close the vial.
6. Hold the wire loop in the flame of the Bunsen burner until the
flame changes colour. Record the name of the sample and the
colour of the flame in your chart. Rinse the wire loop well in a
stream of water.
7. Repeat Steps 5 and 6 for each sample.
8. Follow your teacher's instructions for the disposal of the
materials and equipment.
9. Wash your hands thoroughly with soap and water.
A. Which element is responsible for the flame colours in each
substance observed? T/I
B. If your teacher gave you an unlabelled salt, and it turned the
flame colour violet, what would this tell you? T/I
C. Why should you clean off the wire loop each time or use a
different wire loop for each test? T/I
D. How might you use a flame test to determine which metal is in
an unknown sample? T/I
E. Look at Figure 8. How might you use a flame test to
determine which metal is responsible for this green firework
display? T/I
BEGIN FIGURE CAPTION:
Figure 8 The colour of the explosion tells you what metal is in
the fireworks.
BEGIN PRODUCER’S NOTE:
Figure not reproduced.
END PRODUCER’S NOTE.
END FIGURE CAPTION.
END TEXTBOX.
PRINT PAGE 217
6.1 Wrap Up
- Protons and neutrons are found in the nucleus of the atom.
Electrons orbit the nucleus.
- Protons are positively charged and have about the same mass
as neutrons, which have no charge. Electrons are negatively
charged and have very little mass compared to protons and
neutrons.
- The numbers of protons and electrons in an atom are equal. The
positive and negative charges cancel out each other, giving the
atom a neutral charge.
- Elements cannot be broken down into simpler substances.
- The elements in the periodic table are in order by increasing
atomic number.
- Elements in the same group have similar properties.
BEGIN TEXTBOX:
CHECK YOUR LEARNING
1. Name the three subatomic particles. K/U
2. How many electrons would an atom with the atomic number
12 have? T/I
3. Why does an atom have a neutral charge? K/U
4. (a) Why do potassium oxide and potassium chloride give off
the same colour of light in a flame test?
(b) How does a fireworks technician make use of this property?
K/U, C, A
5. Write the chemical symbol for each element listed below. K/U
(a) aluminum
(b) fluorine
(c) phosphorus
(d) titanium
(e) carbon
(f) gold
(g) potassium
(h) zinc
6. Write the name for the element indicated by each symbol
below. K/U, C
(a) As
(b) B
(c) Cu
(d) Pb
(e) Ag
(f) Ca
(g) Fe
(h) W
7. What is an atomic number? Why is it important? K/U
8. An investigator suspects that water found at a crime scene was
poisoned with barium nitrate. What experiment could be done to
test the suspicion? A
9. The model in Figure 9 shows an atom of the element nitrogen.
K/U
BEGIN FIGURE CAPTION:
Figure 9
BEGIN PRODUCER’S NOTE:
Figure not reproduced.
END PRODUCER’S NOTE.
END FIGURE CAPTION.
(a) How many protons are in one atom of nitrogen?
(b) How many electrons are in one atom of nitrogen?
(c) How many electrons are in the outer orbit of an atom of
nitrogen?
10. Why do all alkali metals have similar reactions? K/U
11. Copy Table 2 into your notebook. Use the periodic table to
complete it. T/I, C
Table 2
Element
Symbol
hydrogen
Ca
phosphorus
Number of Number of
protons
electrons
1
Atomic
number
20