Metals

1
Metals

• Year 10

2
ATOMS
Atoms are the building blocks of all matter. An
atom is made up of smaller bits called
Name Charge Position Mass



Protons
ve
Nucleus
1
Electrons
-ve
Outside
0
Neutrons
neutral
Nucleus
1
All atoms have a defined number of protons.
3
ELEMENTS
An element is a substance made up of only 1 type
of atom. There are about 112 different atom
types therefore there are 112 elements. These are
shown on the periodic table of the elements.
On the periodic table each atom type has its
information. For example
Atomic no.
Symbol
Name
Mass no.
4
PERIODIC TABLE
Atomic no.
Any atom can be identified by the atomic no., the
symbol or by the name. For instance...
Symbol
Name
Name Symbol Atomic No.
Hydrogen
Fe
12
H
1
Iron
26
Magnesium
Mg
The information from the table can also be shown
as
5
WHAT IT MEANS
The Atomic Number number of protons number
of electrons (as an atom has the same of each)
The Mass Number number of protons neutrons -
why are electrons not included in the mass
no? They have no mass!
So for Boron Protons Electrons Neutrons
What about Phosphorus? Protons Electrons
Neutrons
15
5
15
5
5.811
16
6
Learning Check

• Select the correct symbol for each
• A. Calcium
• 1) C 2) Ca 3) CA
• B. Sulfur
• 1) S 2) Sl 3) Su
• C. Iron
• 1) Ir 2) FE 3) Fe

7
Learning Check

• Select the correct name for each
• A. N
• 1)neon 2)nitrogen 3)nickel
• B. P
• 1)potassium 2)phlogiston 3)phosphorus
• C. Ag
• 1) silver 2)agean 3)gold

8
ELECTRON ARRANGEMENT
Electrons are very fast moving. They are arranged
in shells around the nucleus. The first shell
fits The second fits The third fits So the
electron shell configuration for 12Mg would be
2 e
8 e
8 e
2, 8, 2
What is the electron configuration of Li (2,1)
Ca (2,8,8,2) P (2,8,5) What element is
represented by 2,8,7 (Cl) 2,6 (O) 2,8,1 (Na)
9
GROUPS
The columns in the periodic table are called
groups. Groups of elements share similar
reactivity. This is because they have the same
number of valence electrons. As you go down a
group the reactivity increases. Group 1 are the
alkali metals properties good
conductors solid at room temperatures can be
cut with a knife low densities and melting
points Group 17 are the Halogens
10
Periods

• The rows in the periodic table are called
  periods.
• Atoms size decreases from left to right in a
  given period

11
Learning Check

• A. Element in Group XVII, Period 4
• 1) Br 2) Cl 3) Mn
• B. Element in Group II, Period 3
• 1) beryllium 2) magnesium 3) boron

12
IONS
An ion is an atom that has gained or lost
electrons meaning it is negatively or positively
charged. Atoms do this to get a full outer
(valence) electron shell and so becomes more
stable (less reactive). The atom will get a full
outer shell the simplest way it can, e.g. for
12Mg - Electron arrangement of 2, 8, 2 - it
will LOSE 2 electrons (become 2, 8) - Now it has
10 electrons, but still has 12 protons. It has a
2 charge. The ion is called Mg2.
Superscript is used for ion charges
13
IONIC COMPOUNDS
The ions that have been formed are now attracted
to oppositely charged ions. So Mg2 will be
attracted to Cl-. This forms an ionic
compound. Naming rules - The positive ion is
first, and the negative second. - The negative
ion ends in ide, e.g. The sulfur atom becomes
the sulfide ion. Exceptions NO3-
(nitrate) SO42- (sulfate) CO32- (carbonate)
HCO3- (hydrogen carbonate)
14
Ionic Bonding

• Na Cl
• 2,8,1

2,8,7
15
IONIC FORMULAE
So Mg2 will be attracted to Cl-. Because Mg is
2 and Cl is only 1-, Mg will attract 2 Cls. The
compound formed will be MgCl2.
The subscript shows that there are 2 Cls for
each Mg.
If the starting ions were Cu2 and S2-, the 2
ions have the same charge. So each Cu will only
attract 1 S. The compound formed will be CuS.
There is never any charges on the final product -
they balance out
16
Bases that dissolve in water are called
alkalis. It is difficult to test the pH of bases
that do not dissolve in water.
17
DIFFICULT ONES
What is the formula for Magnesium Nitrate? Find
the 2 ions on your table of ions Mg2 and NO3-
This means that there are 3 oxygens attached to
the Nitrogen dont let them get lost!
So for each Mg we will need 2 NO3s
The shorthand way of writing this is Mg(NO3)2
The brackets are needed to show that we want 2 of
the whole thing you always need them if you
have 2 of an ion with more than 1 bit.
(polyatomic ions)
NH4 and S2- Fe3 and OH- Al3 and SO42-
(NH4)2S
Fe(OH)3
Al2(SO4)3
Kahoot
18
Physical Properties of Metals

• The characteristics of a substance that can be
  observed without changing the substance.
• Conductivity (thermal/electrical)
• State (melting point)
• Colour
• Malleability
• Lustre
• Density
• Ductility

19
Chemical Properties

• The characteristics of a substance that can only
  be observed during a reaction which changes the
  substance.
• Reaction with Oxygen
• Reaction with water
• Reaction with acid

The metals you need to know about
are Ca Mg Al Zn Pb Cu Fe Na and be able to
relate their chemical and physical properties to
their uses.
20
HMS Sheffield

• What can you say about the PHYSICAL properties of
  the metal this ship is made from?
• What about its CHEMICAL properties?

21
HMS Sheffield
22
METALS

• Metals can be described by their
• Electrical conductivity
• Thermal (heat) conductivity
• Density
• Lustre
• Malleability
• Colour
• State
• Ductility

they are they are they are they are when
freshly cut they are more or less silver
except Cu and Au solid except Hg varies
The metals you need to know about
are Na Ca Mg Al Zn Fe Pb Cu and be able
to relate their chemical and physical properties
to their uses.
23
Reactivity Series

• Potassium
• Sodium
• Calcium
• Magnesium
• Aluminium
• Zinc
• Iron
• Tin
• Lead
• Copper
• Silver
• Gold

Increases
Chemical reactivity generally involves atoms
gaining or losing electrons. Why?
24
Metals and Nonmetals

• Metals
• Located to the left of the heavy line
• Shiny, ductile
• Good conductors of heat and electricity
• Nonmetals
• Located to the right of the heavy line
• Dull and brittle
• Poor conductors, good insulators

25
METAL REACTIONS
1. METAL OXYGEN Metals react in air to give
metal oxides. Heating increases the rate of this
reaction. Metal oxides are Basic, but only the
first 2 groups of the periodic table are alkalis
(bases that dissolve in water). An example
Magnesium is reacted in the air (with O2) to
produce a white powder, which turns litmus paper
blue. Write the word and balanced symbol equation
for the reaction.
Magnesium
Oxygen
Magnesium oxide
Mg
O2
MgO
2
2
General eqn
26
2. METAL WATER Metals react in water to give
Hydrogen gas (H2) and a Metal Hydroxide. Reaction
speed depends on the reactivity of the metal, but
only the more reactive metals react with
water. An example Sodium reacts violently when
placed in water. The gas produced sometimes
explodes. As this occurs universal indicator
changes from green to purple.
Group 1 metal reactions
Sodium
Water
H2
Sodium Hydroxide
2
Na
H2O
H2
NaOH
2
2
General eqn
27
3. METAL ACID Metals react in acid to give
Hydrogen gas (H2) and a metal salt. Reaction
speed depends on the reactivity of the
metal. These ones react with acids. An
example Magnesium fizzes when placed in a test
tube with Hydrochloric acid. The gas produced
explodes with a squeaky pop.
Magnesium
Hydrochloric acid
H2
Magnesium Chloride
2
Mg
HCl
H2
MgCl2
General eqn
28
Metal Reactions Summary
General Equation

• Metal Oxygen ? Metal oxide
• Aluminium Oxygen ? Aluminium oxide
• 4Al 3O2 ? 2Al2O3
• Metal Water ? Metal hydroxide Hydrogen
• Aluminium Water ? Aluminium Hydroxide
  Hydrogen
• 2Al 6H2O ? 2Al(OH)3 3H2
• Metal Acid ? Metal salt Hydrogen
• Magnesium Hydrochloric acid ? Magnesium
  Chloride Hydrogen
• Mg 2HCl ? MgCl2 H2

Word Equation
Formula Equation
29
CORROSION - the consequence of oxidation
Corrosion, or tarnishing, or oxidation is the
name given to the (usually) slow reaction of
metals to give a metal oxide. Rusting is the
special name for the corrosion of iron into iron
oxide (Fe2O3), or rust. For corrosion to occur
there must be 2 other things present
Water (H2O) and Oxygen (O2)
30
Why are cars and aeroplanes needed for spare
parts are often stored in the desert?
Prevention of corosion
There is less moisture in the atmosphere,
therefore slower rusting.
31
Anchor from the Empress of Asia

• Deep water has little dissolved oxygen and is
  very cold.
• So rusting happens very slowly.
• Once iron is brought to the surface, however, it
  rusts very fast.

32
Preventing Corrosion
To prevent corrosion, the metal can be treated
by Painting Oiling Galvanising coating with Zn
so that it reacts first Adding a sacrificial
metal usually a zinc block reacts first so
the metal does not. This is used in a marine
environment.
33
ALUMINIUM
Aluminium is high on the reactivity series, but
never seems to do anything. Why? Aluminium forms
an oxide coating very quickly. Aluminum oxide is
shiny and silver so it looks like the metal but
it doesnt react. That is why aluminium is used
for many things even though it is reactive. Can
you think of some everyday objects made of
Aluminium?
34
Which is the best pot for cooking?

• Copper, Iron, stainless steel
• Think about the physical and chemical properties
  of each
• How will they help or hinder cooking
• Write the equations for Copper reacting with
  Hydrochloric acid and water?

35
Why is Copper used for wires?

• What is the chemical symbol?
• Give 2 physical properties that make it suitable
  for wires.
• Why is Aluminium used for overhead power lines?

Kahoot
36
THE GAS TESTS
Hydrogen gas (H2) is colourless, odourless, less
dense than air and neutral. How do we test for
it? It burns with a distinctive squeaky
pop. Try it. In a test tube add 2 mL (about 2cm)
of HCl, and 1cm of Mg ribbon. Collect under
thumb and explode!
What type of reaction is this?
Write the equation
37
(No Transcript)
38
Oxygen gas (O2) is colourless, odourless, the
same density as air and neutral. How do we test
for it? It relights a glowing splint. Try it. In
a test tube add 2 mL (about 2cm) of Hydrogen
peroxide (H2O2), and add a tiny pinch of
Manganese dioxide. Collect under thumb and see
how many times you can relight your splint.
39
Carbon Dioxide gas (CO2) is colourless,
odourless, more dense than air and basic. How do
we test for it? It turns limewater milky Try
it. In a test tube add 2 mL (about 2cm) of HCl,
and add a limestone chip (CaCO3). Bubble into
limewater using a collection tube and observe
over a couple of minutes.
What type of reaction is this?
Write the equation
40
Rates of Reaction

• Factors increasing the rate of reaction
• Surface area
• Concentration
• Temperature
• Catalyst/Enzyme
• Pressure