A Material World
Chemicals and Materials
Brainstorm
• Identify all the chemicals in your house…
• Ideas: baking powder, bleach, battery acid, boric acid,
antiperspirant, aspirin, bronze, brass, chalk, diamond,
draino, egg shells, graphite, gypsum, lime, liquid paper,
marble, margarine, moth balls, msg, pewter, plaster, salt,
sand, silicon gel, solder, sugar, Teflon, all medications,
vinegar, vitamin c, washing liquid, windex…..
Phet Simulation
• Build an Atom!
• https://phet.colorado.edu/en/simulation/build-an-atom
• Click play and explore the 3 areas!
• Make sure you tick all the optional boxes – is your atom
stable? Why or why not?
Atoms
• Atoms can’t be divided.
• Atoms are made of smaller particles:
– Protons
– Neutrons
– Electrons
• All substances are made from atoms.
• Each element is made of one type atom.
DRAW
ONE!
Elements
If you burn paper you are left
with ash. What does this tell you
about the type of elements used
to make paper?
• A pure substance which can’t be made into anything
simpler.
• Substances with one type of atom.
• 92 native elements (25 more are artificial)
• Few substances exist as elements, e.g Gold or Diamond
(carbon)
Why the Periodic Table is special
• It is the most powerful icon in science: a single
document that consolidates much of our knowledge
of chemistry.
• Hangs on the wall of nearly every chemical laboratory
and lecture hall in the world.
• This system for classifying the elements represents the
work of many scientists.
How to use the Periodic Table
• Stable atoms are electrically neutral (no charge).
• Therefore, have the same number of electrons (negative)
as protons (positive) recall neutrons are neutral
• Atomic number = the number of protons in an atom
atomic
number
= number of
protons
=
number of
electrons
Atomic mass (weight) = Number of protons + neutrons
(Electrons have almost no mass)
Therefore,
mass = number of
number
protons
+
number of
neutrons
These numbers can be shown as:
This indicates that the atom is
fluorine and has:
• 9 protons and 9 electrons
• 10 neutrons
Atomic mass - Atomic number = no. neutrons
19 - 9
= 10
Complete the worksheet
Try these…
Electron shells
• Worksheet – number of protons, neutrons, electron in an
atom, electron shells.
• Colour code periodic table according to how many
electrons in outer shell
• These extra electrons are called valence electrons
Valence electrons
• These are the electrons in the outer shell of an atom.
• If the electrons in the outer shell are 3 or less – the
electrons can be lost (stolen).
• If there are 4 or more electrons in the outer shell, the
atom will gain (steal) electrons from the other atoms.
The Pattern
• Number of electrons in outer shell = number of valence
electrons.
• Number of electrons in outer shell are the same in each
group of the periodic table.
• Groups are named based on this!
Label the groups on your periodic table!
Group names
Ions
• Outer electron shells want to be full
(shell 1 wants 2 electrons
rest of shells want at least 8 electrons)
• When it is not full the atom has a charge.
• We call them ions.
Mg+2
Positive or negative
• If they lose electrons to become stable it is a positive ion.
• If it gains electrons to become stable it is a negative ion.
• When atoms meet they can give or take each others
electrons to fill their own outer shell.
How do the charges work together?
IONS
• Elements combine in specific ratios to form
compounds.
• While atoms are neutral, ions are charged particles.
• A loss of electrons results in a positive ion, called
cations (“cat-eye-ons”)
• A gain in electrons results in a negative ion, called
anions (“an-eye-ons”)
• The charge of an ion can be determined by how many
electrons are in the outer shell of an atom of the
element.
Element
Atomic #
# Electrons
# electrons
in outer shell
Gain or
lose?
Charge
Ion symbol
Sodium
11
11
(2,8,1) = 1
Lose
+1
Na+
Oxygen
8
(2, 6)
=6
Gain
-2
O-2
(2, 7)
=7
Fluorine
IONIC COMPOUNDS
• Ionic compounds are the result of cations combining
with anions.
• They are attracted by opposite charges.
• Ions wish to have a neutral charge. To do this their
outer shell must be full.
• To do this all positive charges must be counterbalanced
by an equal number of negative charges.
E.g. sodium ion carries a 1+ charge. Chloride ion carries a 1- charge.
When sodium reacts with chlorine it only needs 1 of each atom to
become neutral
Na+ + Cl-  NaCl
+1
-1 = 0
Na+
Cl+
+1
-1
0
E.g. is the reaction of sodium ion with an oxide ion. Sodium has a 1+ charge and the
oxide a 2- charge. When sodium reacts with oxygen it needs two sodium ions to
balance the oxygen ion and become neutral
2 Na+ + O2-  Na2O
2 (+1)
-2
0
Na+
Na+
O2-
+2
-2
0
 When writing formulas for ionic compounds, we use subscripts to indicate how many of each
atom is contained in the compound.
Naming Ions
• Simple cations are named by saying the element and
adding the word “ion.”
Na+ is called “sodium ion”
Mg2+ is called “magnesium ion”
• Simple anions are named by dropping the ending off
the element name and adding “ide.”
F- is called “fluoride”
O2- is called “oxide”
N3- is called “nitride”
• The metal ion (cation) is always written first, and it is
only the non-metals name that changes. NaCl is called
“sodium chloride,” and CaCl2 is called “calcium
chloride.”
Combining
element ions
Sodium and
oxygen
Magnesium
and sulphur
Potassium
and chlorine
Calcium and
nitrogen
Positive
Ion
Na +
Negativ
Electron
e Ion
transfer
O 2Na+
O22(+1) - 2 = 0
Mg2+ S2+2
-2 =0
Chemical
Name
formula
Na2O
Sodium oxide
MgS
Magnesium sulphide
Ions Get Together!
Aim: To construct models of ion compounds using a jigsaw.
• Copy this table into your book
Compound
Positive Ion
Negative
Ion
Compound
formula
Total
positive
charge
Total
negative
charge
Overall
compound
charge
• Colour in your ions.
• Create these compounds using your jigsaw pieces;
sodium fluoride
magnesium fluoride
sodium oxide
magnesium oxide
magnesium nitride
sodium nitride
aluminium fluoride
aluminium oxide
Now try drawing your own ionic compounds for; lithium chloride, calcium bromide, barium sulphide
aluminium
Refresh – Atoms
• Atoms are the smallest unit of matter
Oxygen atom
Oxygen (O2) molecule
Molecules = Atoms joined together
MATTER
Element
Compound
Mixture
Elements
• One kind of atom
• Pure
• Separated in nuclear reactions
Compounds
• 2 or more types of atom.
• Chemically bonded together.
• Formed and separated by chemical
reactions (gain, lose or share electrons).
• Have very different properties to the elements
that make them up.
Eg.
sodium – a silvery metal
chlorine – a green gas
sodium chloride – table salt
Atoms /
Elements
Elements /
Molecules
Molecules /
Compounds
Water
(H2O)
Hydrogen (H)
Hydrogen gas (H2)
Oxygen (O)
Methane
(CH4)
Carbon (C)
Oxygen gas (O2)
Mixtures:
• 2 or more elements or compounds physically
together
• Not pure
• Separated physically (e.g. strainer)
No new compound is formed.
Examples?
Are these
compounds,
mixtures,
molecules or
elements?
ELEMENT
MOLECULE
COMPOUND
MIXTURE
Worksheet – Elements, Compounds and Mixtures
FRAYER SQUARE
DEFINITION:
EXAMPLES:
CHARACTERISTICS:
COMPOUNDS
NON-EXAMPLES:
History of the Periodic Table
• What did the Ancient Greeks think about matter?
• What did they think about matter in the Middle Ages?
• What do we know about chemistry in modern times?
• Research and make a concept map!
Approx. 2000
years ago
Part experiment
part mystical
magic
Alchemy
“Transmute”
metals to gold
Democritus
~460BCE
“atomos” can’t be
divided
Approx. 1000
years ago
IDEAS OF
ELEMENTS
MIDDLE
AGES
Discovered
facts about:
Solids, liquids
and gases
ANCIENT
GREEKS
Invented:
- Distillation
- Filtration
- Crystallisation
Only discussed ideas
– No experiments!
Aristotle 384-322BCE
Questioned what is everything
made of?
‘Elements’ – water, air, fire and
earth
Element –
Approx. from simplest basic
form of matter
1800’s to
current
MODERN
CHEMISTRY
Understand:
Particles
Forces &
energy
Chemical
114 elements
discovered
(92 occur
naturally)
Timeline of Atom
•
•
•
•
•
•
•
Democratus and Aristole
Joseph John Thompson
Ernest Rutherford
Niels Bohr
James Chadwick
Erwin Schrödinger
Werner Heisenberg
In groups, choose one of these scientists.
Make a poster for a timeline that tells us
the following:
- YEARS
- NAME
- THEORY and/or DISCOVERY
- DRAWING OF THEIR MODEL OF
AN ATOM
Metals
Brainstorm – what properties do metals have?
Malleable, Ductile, Lustrous and Conductive (Electrical and Heat)
Prac – Metallic crystals
Research
• What are 10 uses for pure metals. Specify which metal is
used for what.
• Alloys:
•
•
•
•
What are they?
How are they made?
Why use them instead of a pure metal?
10 examples of alloys and their uses.
Plastics