11. patterns in the periodic table v1.0

2 of 44 © Boardworks Ltd 2007

© Boardworks Ltd 20073 of 44
• The atomic model has
changed throughout the
centuries, starting in 400
BC, when it looked like a
billiard ball →

Who are these men?
In this lesson, we’ll learn about
the men whose quests for
knowledge about the
fundamental nature of the
universe helped define our
views.

Democritus
• This is the Greek philosopher
Democritus who began the
search for a description of matter
more than 2400 years ago.
He asked: Could matter be
divided into smaller and smaller
pieces forever, or was there a
limit to the number of times a
piece of matter could be divided?
400 BC

Atomos
• His theory: Matter could not be
divided into smaller and smaller
pieces forever, eventually the
smallest possible piece would be
obtained.
• This piece would be indivisible.
• He named the smallest piece of
matter “atomos,” meaning “not to
be cut.”

Atomos
 To Democritus, atoms
were small, hard particles
that were all made of the
same material but were
different shapes and sizes.
 Atoms were infinite in
number, always moving
and capable of joining
together.

This theory was ignored and
forgotten for more than 2000
years!

Why?
• The eminent
philosophers of the
time, Aristotle and
Plato, had a more
respected, (and
ultimately wrong)
theory. Aristotle and Plato favored the
earth, fire, air and water
approach to the nature of
matter. Their ideas held sway
because of their eminence as
philosophers. The atomos idea

Dalton’s Model
• In the early 1800s,
the English
Chemist John
Dalton performed a
number of
experiments that
eventually led to
the acceptance of
the idea of atoms.

Dalton’s Theory
• He deduced that all
elements are composed of
atoms. Atoms are
indivisible and
indestructible particles.
• Atoms of the same element
are exactly alike.
• Atoms of different elements
are different.
• Compounds are formed by
the joining of atoms of two
or more elements.

.
• This theory
became one
of the
foundations
of modern
chemistry.

Thomson’s Plum Pudding Model
• In 1897, the
English scientist
J.J. Thomson
provided the first
hint that an atom
is made of even
smaller particles.

Thomson Model
• He proposed a model of the
atom that is sometimes called
the “Plum Pudding” model.
• Atoms were made from a
positively charged substance
with negatively charged
electrons scattered about,
like raisins in a pudding.

Thomson Model
• Thomson studied
the passage of an
electric current
through a gas.
• As the current
passed through the
gas, it gave off rays
of negatively
charged particles.

Thomson Model
• This surprised
Thomson,
because the
atoms of the gas
were uncharged.
Where had the
negative charges
come from?
Where did
they come
from?

Thomson concluded that the
negative charges came from
within the atom.
A particle smaller than an atom
had to exist.
The atom was divisible!
Thomson called the negatively
charged “corpuscles,” today
known as electrons.
Since the gas was known to be
neutral, having no charge, he
reasoned that there must be
positively charged particles in
the atom.
But he could never find them.

Rutherford’s Gold Foil Experiment
• In 1908, the
English physicist
Ernest Rutherford
was hard at work
on an experiment
that seemed to
have little to do
with unraveling the
mysteries of the
atomic structure.

• Rutherford’s experiment Involved
firing a stream of tiny positively
charged particles at a thin sheet of
gold foil (2000 atoms thick)

Most of the positively
charged “bullets” passed
right through the gold
atoms in the sheet of gold
foil without changing
course at all.
Some of the positively
charged “bullets,” however,
did bounce away from the
gold sheet as if they had
hit something solid. He
knew that positive charges
repel positive charges.

• This could only mean that the gold atoms in the
sheet were mostly open space. Atoms were not a
pudding filled with a positively charged material.
• Rutherford concluded that an atom had a small,
dense, positively charged center that repelled his
positively charged “bullets.”
• He called the center of the atom the “nucleus”
• The nucleus is tiny compared to the atom as a
whole.

Rutherford
• Rutherford reasoned
that all of an atom’s
positively charged
particles were
contained in the
nucleus. The
negatively charged
particles were
scattered outside the
nucleus around the
atom’s edge.

Bohr Model
• In 1913, the
Danish scientist
Niels Bohr
proposed an
improvement. In
his model, he
placed each
electron in a
specific energy
level.

Bohr Model
• According to Bohr’s
atomic model,
electrons move in
definite orbits around
the nucleus, much like
planets circle the sun.
These orbits, or
energy levels, are
located at certain
distances from the
nucleus.

Wave Model

The Wave Model
• Today’s atomic model is based
on the principles of wave
mechanics.
• According to the theory of
wave mechanics, electrons do
not move about an atom in a
definite path, like the planets
around the sun.

The Wave Model
• In fact, it is impossible to determine the exact
location of an electron. The probable location of
an electron is based on how much energy the
electron has.
• According to the modern atomic model, at atom
has a small positively charged nucleus
surrounded by a large region in which there are
enough electrons to make an atom neutral.

Electron Cloud:
• A space in which
electrons are likely to be
found.
• Electrons whirl about the
nucleus billions of times
in one second
• They are not moving
around in random
patterns.
• Location of electrons
depends upon how much
energy the electron has.

Electron Cloud:
• Depending on their energy they are locked
into a certain area in the cloud.
• Electrons with the lowest energy are found
in the energy level closest to the nucleus
• Electrons with the highest energy are
found in the outermost energy levels,
farther from the nucleus.

IndivisibleIndivisible ElectronElectron NucleusNucleus OrbitOrbit ElectronElectron
CloudCloud
GreekGreek XX
DaltonDalton XX
ThomsonThomson XX
RutherfordRutherford XX XX
BohrBohr XX XX XX
WaveWave XX XX XX

What is the periodic table?
Mendeleev created the first modern periodic table.
What does it show and why is it always in the same order?

What is an element?

Where were the elements made?
There are 92 naturally-occurring elements and about 15
artificially-produced elements.
Elements were originally made in
stars. In the early stages of a star’s
life, light elements, such as
hydrogen and helium, are formed.
These fused together to make
heavier elements such as carbon.
Some of the even heavier elements
were produced deep within stars
and were sent out into the Universe
when the stars exploded.
Most of the artificially-produced elements have only been
made in nuclear reactors or particle accelerators.

What is the atomic number?
Every element has a unique atomic number. This is the
number of protons in the nucleus of each atom.
What is the atomic number of
this helium atom?
A neutral atom must have equal numbers of protons and
electrons, so the atomic number of an element also gives
the number of electrons.
Helium has 2 protons, so its
atomic number is 2.
Atoms are neutrally charged,
so what links atomic number
and the number of electrons?
electron
proton
neutron

What are the properties of elements?
A property is any characteristic feature of a substance.
Properties of sodium include:
The chemical properties of an element are
determined by its atomic number.
Are there any patterns in the properties of the elements?
 highly reactive
 solid but melts easily
 feels light (low density).
Can you name any properties
of the element sodium?
A property is any characteristic feature of a substance.

How was the periodic table developed?

How are the elements arranged?

The periodic table
Arranging all the elements by their atomic number and their
properties led to the creation of…
…the periodic table
Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg ? ? ? ? ? ? ?
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Na Mg Al Si P S Cl Ar
Li Be B C N O F Ne
H He

Missing elements!
In this periodic table the symbols are replaced by atomic
numbers. Some of the numbers are missing – where?
87 88 89 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118
55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
37 38 39 40 41 42 43 44 45 46 47 38 49 50 51 52 53 54
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
11 12 13 14 15 16 17 18
3 4 5 6 7 8 9 10
1 2
Two more rows of elements fit here.
They are called the lanthanides
and actinides.

The elements in the periodic table

Columns of elements
What are columns of elements called?
groups1 2 43 5 6 07

Rows of elements
periods
What are rows of elements called?
1
2
3
4
5
6
7

Patterns: metals and non-metals
on the right (except hydrogen)
Where are these different types of elements grouped
together in the periodic table?
metals
non-metals
between metals and non-metalssemi-metals
on the left and centre
Can you name a semi-metal element?
Semi-metals have some properties similar to metals and
other properties similar to non-metals.

Metals to non-metals, solids to gases

Patterns: reactivity of metals
Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po
Rb Sr Y Zr NbMo Tc Ru Rh Pd Ag Cd In Sn
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga
Na Mg Al
Li Be
What happens to the reactivity of metals down a group?
Which is the most reactive metal?
increase in reactivity
increaseinreactivity
What happens to the reactivity of metals along a period?

Which metal is more reactive?

Patterns: reactivity of non-metals
increase in reactivity
Group 0 elements are the most unreactive of all elements.
For the remaining non-
metals and semi-metals,
reactivity increases up a
group and along a period
from left to right.
Which is the most reactive
non-metal/semi-metal?
At Rn
Sb Te I Xe
Ge As Se Br Kr
Si P S Cl Ar
B C N O F Ne
He
increaseinreactivity
unreactive

Which non-metal is more reactive?

Patterns, atomic number and electrons
What links atomic number and the properties of elements?
The periodic table shows that patterns in the properties of
elements are linked to atomic number.
atomic number = number of protons
atomic number = number of electrons
number of protons = number of electrons
Electrons!
As atomic number increases by one, the number of electrons
also increases by one.
This means that the elements in the periodic table are
also arranged in order of the number of electrons.

How are electrons arranged?
Electrons are arranged in shells around an atom’s nucleus.
(The shells can also be called energy levels).
This electron arrangement is written as 2,8,8.
1st
shell holds
a maximum of
2 electrons
2nd
shell holds
a maximum of
8 electrons
3rd
shell holds
a maximum of
8 electrons
Each shell has a maximum number of electrons that it can
hold. Electrons will fill the shells nearest the nucleus first.

Electron trends in the periodic table
Trends down a group:
The point at which a new period starts is the point at
which electrons begin to fill a new shell.
The number of a group is the same as the number of
electrons in the outer shell of elements in that group,
except for group 0.
 the number of outer shell electrons is the same;
 the number of complete electron shells increases by one.
 the number of outer shell electrons increases by one;
Trends across a period:
 the number of complete electron shells stays the same.

Periodic table and electron structure

Electrons and groups

Groups and periods

What’s the electron arrangement?

Names of groups in the periodic table

Trends in group 1 (Alkali metals)
Element Atomic
number
Mass number Melting
point / C⁰
Boiling
point / C⁰
Li 3 7 180 1360
Na 11 23 93 900
K 19 39 63 777
- The elements in group 1 are called the alkali metals. They
belong to the left-hand column in the periodic table.
-They are very reactive and must be stored in oil to avoid
contact with air or water.
-The alkali metals all have low melting points and boiling
points compared to other metals. The melting points and
boiling points decrease as you go down the group.

Trends in group 7 (THE HALOGENS)
The halogens have low melting points and low boiling points.
This is a typical property of non-metals. Fluorine has the
lowest melting and boiling points. The melting and boiling
points then increase as you go down the group.

Trends in group 0 (noble gases)
Element Atomic
number
Electronic
structure
Mass
number
Melting
point / C⁰
Boiling
point / C⁰
He 2 2 4 -270 - 269
Ne 10 2, 8 20 -249 - 246
Ar 18 2, 8, 8 40 -189 - 186
- Includes the elements helium, neon and argon.
- They are all gases and most are inert (unreactive) and do
not form compounds. They are called noble gases.

Metals and their reaction with oxygen
Metals react with oxygen in the air to produce metal
oxides.
For example, magnesium reacts with oxygen to
produce magnesium oxide when it is heated in air:
Magnesium + oxygen → Magnesium oxide

Reaction of group 1 metals with oxygen
• When pieces of Lithium, Sodium or potassium are take out of
their containers they are dull.
• When they are cut, the surface is shiny.
• They shiny surface soon becomes dull because the metal
reacts with the oxygen in the air (without heating)
• The surface is now covered with
the metal oxide.
• Metal + oxygen → Metal oxide

Reaction of metals with water
• All the alkali metals react vigorously with cold water.
• In each reaction, hydrogen gas is given off and the metal
hydroxide is produced.
• The speed and violence of the reaction increases as you go
down the group. This shows that the reactivity of the alkali
metals increases as you go down Group 1.
• Metal + water → Metal hydroxide + hydrogen
• Group 1 metals react vigorously with water.

• Other metals like calcium and magnesium react much slower.
• The gas (hydrogen) produced can be collected by
displacement of water (apparatus shown below).
• The gas can then be tested to prove it is hydrogen with a lit
splint (a pop sound is heard)

• Magnesium will react faster with steam than water (heated)
• Magnesium oxide and hydrogen are formed.

Reaction of metals with dilute acid
• Magnesium will react with dilute hydrochloric acid to give a
salt and hydrogen
• Magnesium + Hydrochloric acid → Magnesium chloride+ hydrogen
• In your copybook
• Write the word equation for the reaction of the following:
(a)Magnesium and sulphuric acid
(b)Zinc and nitric acid
(c)Calcium and hydrochloric acid

The reactivity series
• In a reactivity series, the most reactive element is placed
at the top and the least reactive element at the bottom.
• More reactive metals have a greater tendency to
lose electrons.

Mnemonic to help you remember the reactivity series:
"Please Sam send Caught Monkeys And Zebras In Lead
Cage with Security Guards."
1. Potassium - K
2. Sodium - Na
3. Calcium - Ca
4. Magnesium - Mg
5. Aluminium - Al
6. Zinc - Zn
7. Iron - Fe
8. Lead - Pb
9. Copper - Cu
10. Silver - Ag
11. Gold - Au

Metal Reaction with oxygen Reaction with water Reaction with acid
Potassium Burns brightly when heated to
form an oxide.
Very vigorous reaction in cold
water. The hydroxide is formed.
Violent reaction and very
dangerous.
Sodium
Calcium Burns brightly in air when
heated to form an oxide.
Slow reaction in cold water to
form the hydroxide.
Magnesium Reaction, which becomes
less vigorous as you go
down the list.
Aluminium
Slow reaction when heated to
form an oxide.
Reacts with steam but not water
to form an oxide.
Zinc
Iron
Lead
No reaction with steam or
water.
Copper
No reaction.
Silver No reaction.
Gold

Displacement reactions
• A more reactive metal will displace a less reactive metal
from a compound.
• More reactive metals have a greater tendency to
lose electrons.
• A more reactive metal will displace a less reactive metal
from a solution of one of its salts. For example:
magnesium + copper sulfate → copper + magnesium sulfate

Using Displacement reactions
Thermite Welding
•A mixture of Aluminium and Iron oxide reacts to produce
molten iron that is used to join railway rails together.
•Aluminium + Iron oxide → Aluminium oxide + Iron
•Aluminium replaces (displaces Iron) in Iron oxide to form
Aluminium oxide.

Extraction of metals
Most metals are found as compounds. These compounds in the
mining industry are called ores.
Ores are usually oxides, carbonates or sulphides of the metal,
mixed with sandy impurities.
Some metals can be extracted from their ores by displacement
reactions.
For example, iron can be extracted from its ore, haematite,
(iron oxide) by heating with carbon at high temperatures. An
industrial scale of extraction of iron is done in a giant blast
furnace.
Iron oxide + carbon → iron + carbon dioxide

1. Potassium - K
2. Sodium - Na
3. Calcium - Ca
4. Magnesium - Mg
5. Aluminium - Al
6. Zinc - Zn
7. Iron - Fe
8. Lead - Pb
9. Copper - Cu
10. Silver - Ag
11. Gold - Au
Carbon
can
displace
elements
below
Aluminium
Hydrogen
can
displace
elements
below Lead
Please Stop Calling Me A Cute Zebra I Like Her Call
Smart Goat

What is a salt?

• Many methods for making salts start with acids.
• The table below gives the formulae of the three common acids
that we can find in the laboratory.
Acids and salts
Name of acid Salts formed from the acid
Hydrochloric acid Chloride
Sulphuric acid Sulphate
Nitric acid Nitrate
Carbonic acid (CO₂ +H₂O) Carbonate
Citric acid (citrus fruits) Citrate

• Reaction of metals with dilute acids produces a salt.
Metal + acid → Salt + Hydrogen
• Example:
Zinc + hydrochloric acid → Zinc chloride + hydrogen
• In your copybook write the word equations for:
(a)Magnesium with Nitric acid
(b)Zinc with Nitric acid
(c)Zinc with sulphuric acid
(d)Aluminium with Hydrochloric acid
Preparing salts using Acids and metal

• Some metals do not react with metals (copper, gold and
silver). They cannot displace hydrogen in the acid.
• So we use their metal oxides instead.
Metal oxide + acid → Salt + Water
• Example:
Copper oxide + hydrochloric acid → Copper chloride + water
(a)Silver with Nitric acid
(b)Copper with Nitric acid
(c)Copper with sulphuric acid
(d)Silver with sulphuric acid
Preparing salts using Acids and metal oxide

• Some metals react with carbonic acid
carbonate + acid → Salt + Water + Carbon dioxide
• Example:
Calcium carbonate + hydrochloric acid →Calcium chloride + water + carbon dioxide
(a)Calcium carbonate with Nitric acid
(b)Calcium carbonate with sulphuric acid
(c)Copper carbonate with Hydrochloric acid
carbonates

• Some metals react with carbonic acid
carbonate + acid → Salt + Water + Carbon dioxide
• Example:
Calcium carbonate + hydrochloric acid →Calcium chloride + water + carbon dioxide
(a)Calcium carbonate with Nitric acid
(b)Calcium carbonate with sulphuric acid
(c)Copper carbonate with Hydrochloric acid
(d)Copper carbonate with Nitric acid
carbonates

• When an acid is neutralized by an alkali, a salt is produced.
Acid + Alkali → Salt + water
• Example:
Sodium hydroxide + hydrochloric acid → Sodium chloride + water
(a)Calcium Hydroxide with Nitric acid
(b)Lead Hydroxide with sulphuric acid
(c)Magnesium Hydroxide with Hydrochloric acid
(d)Iron Hydroxide with Nitric acid
Forming salts by neutralisation

• When soluble metal oxides dissolve in water.
• Example:
Sodium oxide + water→ Sodium hydroxide
• Sodium oxide is a base. Sodium hydroxide is an alkali.
Alkalis and bases

11. patterns in the periodic table v1.0

More Related Content

What's hot

Viewers also liked

Similar to 11. patterns in the periodic table v1.0

More from Reem Bakr

Recently uploaded

11. patterns in the periodic table v1.0

Editor's Notes