Science 14
 Alchemy
was a subject that consisted of
religion, science, and philosophy practiced
from ancient times until the eighteenth
century.
 Many alchemists spent their time trying to
find mixtures that would bring a greater
understanding of eternal life.
 Other alchemists tried to find ways to change
inexpensive raw materials into gold.
 Hennig
Brand – discovered phosphorous
 Phosphorous is a substance that glows in the
dark
 The
early Greeks believed that all matter
was made up of only four elements: earth,
air, fire and water. This theory has since
been replaced.
 By
the mid-1860s, scientists had discovered
64 elements and had recorded many of their
properties.
 Elements
are substances that cannot be
broken down into other substances and
contain only one kind of atom.
 How
can we organize this information?

Science Background:
The development of the periodic table was a
milestone in the study of chemistry. It let scientists
quickly determine which elements have similar
physical and chemical properties, and predict an
element’s properties based on its location in the
table.
 Although elements can be grouped according to their
physical and chemical properties, each element has
its own unique set of characteristics (e.g., melting
point, boiling point, and density) that are slightly
different from those of all neighbouring elements.
This fact helped disprove early theories that only
four elements existed.

 Careful
measurements and investigations
allowed scientists to discover many
elements, each with its own unique physical
and chemical properties.
 John Dalton described elements based on
their relative mass. Using his work, we now
know that different elements with equal
volumes have different masses when
compared to each other. For example, if you
took one litre of hydrogen and compared its
mass to the same volume of oxygen, the
oxygen would be eight times heavier.

Dmitri Mendeleev wrote all the
information for each element on a
separate file card and then put elements
with similar properties in columns.

He organized the elements within each
group from lightest to heaviest.

Then he organized the groups so that the
lightest elements were on the left side of
the table and the heaviest were on the
right side.
 Mendeleev
noticed that some elements
seemed to be missing.
 He
predicted these elements existed but had
not yet been discovered.
 He
made cards for the missing elements and
even predicted their properties
 Mendeleev’s
work provided the basis for the
periodic table!
 The periodic table is a chart on which
scientists have organized all of the elements.
 Mendeleev worked with 64 elements. Since
then, the number of elements has grown to
112.
 Many of Mendeleev’s predicted elements
have been discovered.
 http://www.pbs.org/wgbh/nova/education/
physics/developing-periodic-table.html
 http://science.discovery.com/tv-
shows/greatest-discoveries/videos/100greatest-discoveries-shorts-periodictable.htm
 Elements
in Mendeleev’s chart are made of
atoms.
 Atoms are the smallest units of matter.
 Periodic tables do not all look the same but they
do have some things in common:


They all look like a chart.
Each square of the table
includes information
about one element.
 Periodic
Table: Patterns and Trends

The elements in the periodic table are arranged
in columns and rows so that elements with
similar properties appear together.

Columns = groups

Rows = periods


The modern periodic table separates metals from non-metals
using a staircase-like division on the right side.
Elements around this staircase have properties of both metals
and non-metals. They are called metalloids. For example,
silicon is a dull, brittle solid that conducts electricity well.
 Metals
and Non-Metals
Metals
Non-Metals
-Bright metallic shine
(lustre)
-Easily shaped
(malleable)
-Solids (except
mercury)
-Good conductors of
heat and electricity
-Dull, various colours
-Brittle
-Solids or gas (except
bromine which is liquid at
room temperature)
-Poor conductors of heat
and electricity
 The
elements that touch the bolded staircase
are metalloids with the exception of
aluminum, which is a metal.
 Metalloids
are elements that share some of
the properties of metals and some of the
properties of non-metals.
 http://www.youtube.com/watch?v=zGM-
wSKFBpo
 New
Version
http://www.youtube.com/watch?v=IsBZx0tv6d
Q
 Did

you know?
WWI Gas Mask:
 Chlorine is a very toxic greenishyellow gas. During WWI, some
armies used chlorine gas as a
weapon. Many soldiers died
from inhaling the gas. The gas
mask was invented to prevent
such deaths.
 Is Chlorine a metal or nonmetal?
 Other




important elements:
Hydrogen - in the atomic bomb
Nitroglycerin - in dynamite
Aluminum — most abundant metal; resists
extensive rusting; used in manufacturing and
cosmetics. Linked to Alzheimer’s disease.
Iron — second most abundant metal; used in
steel formation. Steel is a major component in
structures from cars to buildings. Iron is also an
important component of proper nutrition and
health (transports oxygen through the circulatory
system).
 Nitrogen
— most abundant gas in the
atmosphere; required by all living organisms;
major component in fertilizers and
explosives.

Largest single use of nitrogen (30 percent) is in
enhanced oil recovery where pressurized nitrogen gas
forces oil from subterranean deposits. Because it is
non-reactive, nitrogen is also used by metal, chemical,
and computer manufacturers to displace air during
processing.
 Carbon
— the basic component of organic
life; graphite and diamond are the most
common forms found in the environment.


Graphites include charcoal, which may be burned via
combustion to release stored energy.
Carbon is found in a variety of important compounds
including organic compounds. Some of these
compounds may be used as fuels (e.g., methanol and
ethanol) and burned to release great quantities of
energy. This energy is used to provide heat, power,
and transportation.
 Bismuth
– has a very low melting point
(271°C) making it an excellent “plug” for fire
sprinklers. As a fire starts, the air near the
ceiling quickly reaches temperatures up to
500°C. This melts the bismuth plug, letting
the water flow from the sprinkler heads.
 Using
the periodic table found at the back
of your textbook, complete the table on
the next slide/page.
Element Name
Symbol
Period
Group
4
17
1
18
Metal or Non-metal
chromium
P
bohrium
7
15
metal
14
non-metal
tin
Cl
Nb
5
 Complete
the “check your understanding”
questions (#s 1, 2, 4) from p. 30
 Science
 Heating
Background
causes compounds to decompose
because as the particles move faster, the
energy of their movements eventually
outweighs the attraction between the atoms.
This breaks the compound into its component
elements. Running electricity through a
substance works in the same way.
 Decomposition
reactions played a critical
role in finding new elements. Scientists like
Antoine Lavoisier used heat to cause a
decomposition reaction to see if they could
separate a variety of substances into
different elements. This work gave Lavoisier
the name of “father of modern chemistry.”

Lavoisier was able to
predict that water was
made of hydrogen and
oxygen before Sir Humphry
Davy actually used
electrolysis to separate
water into hydrogen and
oxygen. Lavoisier also
developed the principle that
a substance could be
considered an element only
if it could not be broken
down into simpler
substances.
 Elements

and compounds in society:
Can you think of elements and compounds that
we see and use daily?
 Compounds
 The
A
periodic table lists elements.
substance made up of two or more
different elements chemically combined
together is known as a compound.
 Example:
 Oxygen
is a pure substance that consists of a
single element.
 Distilled
water is a pure substance that
consists of more than one element (hydrogen
and oxygen). Therefore, water is a
compound.
 *Most
substances in the world are
compounds.
matter
Pure
substance
element
mixture
compound
 Testing



for compounds:
Recall that an element is an pure substance that
cannot be broken down into simpler substances
Compounds, however, are made up of two or
more elements. Therefore, compounds can be
broken apart into simpler substances.
This process is known as a decomposition
reaction.
 **Video**
BBC Atoms, Molecules, Elements,
Compounds Animation
http://www.youtube.com/watch?v=AfXxZwNLv
PA
 Complete
 Complete
counting atoms worksheet!
the “check your understanding”
questions on p. 34 #1-3.
 Introduction:

The International Union of Pure and Applied
Chemistry (IUPAC) also established standard names
for chemical compounds. Though the rules of
nomenclature developed by IUPAC are beyond the
scope of this course, students may wonder why
they see several names for a single substance. For
example, the labels on iron vitamins may say the
pills contain “ferrous sulfate” even though the
international standard name is iron(II) sulfate.
Different names such as this appear because iron is
the substance’s common name, ferrous sulfate is a
scientific name that predates the IUPAC standards,
and iron(II) sulfate is the internationally recognized
name.

Element symbols – either one or two letters
(often the first letter of the element)
i.e.) C = Carbon
N = Nitrogen
However, once scientists ran out of letters, they
began using the first letter of the element name
and a second letter from the name.
i.e.) Ca = calcium
Zn = Zinc
 Also,
some elements were discovered in
ancient times and have Latin or Greek
names. These elements were given a symbol
based on their historic name.

i.e.) Pb = Lead (which was known in Latin as
plumbum
 Chemical


Formulas:
Used to represent the compounds formed by
elements
= Water
𝑪𝑶𝟐 = Carbon Dioxide
i.e.) 𝑯𝟐 𝑶
Compound
Sodium bicarbonate (baking soda)
Glucose (sugar)
Chemical Formula
 Complete
the “check your understanding”
questions on p. 37 #1-3
 Review
questions on page 38-39