Elementary Particles of Matter.pptx

WEEK 5: ELEMENTARY PARTICLES OF MATTER:
SUB- TOPIC:
Atoms
Molecules
Ions
Valency
Radicals
Sunday, January 15, 2023

Learning objectives
• At the end of this lesson, students should be able to:
• Define atoms with examples
• Describe the structure of atoms.
• Explain the constituents of atom and their characteristics.
• State Daltons atomic theory and its modification.
• Arrange electrons in the KLMN shells.
• Define molecules with examples
• Define atomicity
• Explain the types of atomicity
• Calculate the atomicity of elements and compounds

Learning objectives
• Define ions with examples.
• Explain the types of ions with examples.
• Define valency with examples
• Explain the classification of valency.
• Write the first twenty elements and their valencies
• Define radicals with examples.
• Write the chemical formula of various compounds via exchange of radicals

Elementary particles of matter
• Definition of matter
• Matter is anything that has mass and occupies space.
• Constituents of matter
• Matter is made up of three major discrete particles, such as:
• Atoms
• Ions
• Molecules

Atoms
• Definition of atoms
• Atoms are the smallest particle of an element that can take part in a chemical
reaction.
• Atoms can also be defined as the smallest part of an element that can ever exist and
still possess the chemical properties of that element.
• They are units which are concerned in chemical reactions.
An atom of Symbol
Oxygen O
Chlorine Cl
Silver Ag
Carbon C

Constituents of atoms
• Atoms are made up of Protons, Electrons and Neutrons (PEN)
• Discovery of Sub-atomic particles:
S/N SCIENTIST DISCOVERY EXPERIMENT
1 J.J Thompson Protons Discharge Tube Experiment
Electrons Discharge Tube Experiment
2 James Chadwick Neutrons Alpha Scattering Experiment
3 Ernest
Rutherford
Nucleus of an Atom and Planetary
Bodies
Alpha Scattering Experiment
4 Niel Bohr Energy Levels Quantization Hydrogen Spectrum

Structure of an atom

Structure of an atom: J.J Thompson’s model
• J.J Thompson described the atom as
being made up of a mixture of positive
(Protons) and negative (Electrons)
charges.
Structure of an atom: Lord Rutherford’s model
+ _ + _ +
+ _ + _ +
+ _ + _ +
He used the planetary bodies rotating around the
sun to describe the structure of atoms.
+ +
+ +
+ +
Sub-Particle Location Relative Charge Relative Mass
Proton Nucleus + 1
Electron Outside Nucleus - 1/1840 = 0.0005
Neutron Nucleus Zero 1

Daltons Atomic Theory
S/N Theory Modification Discovery that led to th
modification
1 All elements are made up of
small indivisible particles
called atoms
Elements are made up of atoms and these atoms are divisible
and made up of three main sub-atomic particles: Protons,
neutrons and electrons.
Subatomic particles
Protons, neutrons an
electrons.
2 The atom can neither be
created nor destroyed
Atoms can neither be created nor destroyed during ordinary
chemical reactions only, during nuclear reactions, atoms can
be created and destroyed.
Nuclear reaction
(Radioactivity)
3 The Atoms of the same
elements are alike in every
aspect and differ from atoms
of all other elements
Atoms of the same elements are not exactly alike because
they can possess same number of protons but different
number of neutrons.
Isotopy
4 During a chemical reaction,
There is a combination of
atoms in small whole numbers
During chemical reactions involving inorganic compounds
only, the combination of atoms is in small whole numbers
but reactions involving organic compounds can be in large
numbers, fractions etc.
Reactions involving organi
compounds
5 All chemical changes result
from the combination or the
separation of atoms
No modification None

Test
1. Name and give the symbols of the first 30 elements 30 marks.
2. state Dalton’s atomic theory and its modifications. 10marks
3. Copy and complete the table below (9marks)
4. Draw the structure of an atom according to
(a) J.J. Thompon’s model (2marks)
(b) Lord Rutherford’s model (2marks)
5. Explain how to separate a mixture of sand, iron filings, salt and iodine crystals
(10marks)
Sub-Particle Location Relative Charge Relative Mass
Proton
Electron
Neutron

1 Elements are made up of small
indivisible particles called
atoms
Atoms are divisible and made up of
Protons, neutrons and electrons.
2 Atom can neither be created
nor destroyed
During nuclear reactions, atoms can be
created and destroyed.
3 Atoms of the same elements are
alike in every aspect and differ
from atoms of all other
elements
In isotopy atoms can possess same
number of protons but different number
of neutrons.
4 Atoms combine in small whole
numbers.
Reactions involving organic compounds
can be in large numbers, fractions etc.
5 All chemical changes result
from the combination or the
separation of atoms
No modification
Sub-
Particle
Location Relative
Charge
Relative Mass
Proton Nucleus + 1
Electron Outside
Nucleus
- 1/1840 = 0.0005
Neutron Nucleus Zero 1
1
3
2

4. J.J. Thompon’s model • Lord Rutherford Atomic Model
+ _ + _ +
+ _ + _ +
+ _ + _ +
+ +
+ +
+ +
5
I. Remove iron filings from the mixture with a magnet.
II. Heat for iodine to sublime.
III. Take the remaining mixture and add water. The salt dissolves in water
and everything else does not. Filter the mixture into a beaker
IV. Evaporate the water to give salt in the beaker.

Molecules
• Definition of molecules:
• A molecule is the smallest particle of a substance that can normally exist alone and still
retain the chemical properties of that substance, be it an element or a compound.
• Some molecules can exist independently as single atoms e.g. He, Na, Ca, Mg etc.
• Some molecules may be made up of atoms of the same element e.g. a molecule of hydrogen is
H2, that of chlorine is Cl2, oxygen is O2, phosphorus is P4, sulphur is S8.
• Some molecules may be made up of different elements e.g. a molecule of water is H2O,
methane is CH4, ammonia is NH3, carbon (iv) oxide is CO2 etc.

Elements
• Definition of elements:
• An element is a substance that cannot be broken down into simpler units by ordinary chemical
process.
• Atomicity of Elements
• Atomicity of an element is the number of atoms in each molecule of an element.
• Monoatomic:
An element is said to be Monoatomic if it contains on atom in its molecule e.g Helium (He), Neon
(Ne), Sodium (Na), Argon (Ar) each have atomicity of 1.
Note: Metals are generally monoatomic (i.e they have atomicity of 1). Noble gases are also
monoatomic.
• Diatomic:
An element is said to be diatomic if it contains two atoms in its molecule e.g Oxygen (O2),
Chlorine (Cl2), Nitrogen (N2), Fluorine (F2).
• Triatomic:
An element is said to be triatomic if it contains three atoms in its molecule e.g. Ozone (O3).

Determination of the atomicity of an element or compound
• The atomicity of an element can be determined by:
1. Counting the number of atoms present in the element or compound
2. Calculating the atomicity using the formula below:
(a) Relative molecular mass (R.M.M)/ Relative atomic mass (R.A.M)
(b) (Vapour density x 2)/Relative atomic mass (R.A.M).
Examples:
Determine the atomicity of compounds listed below:
(a) H2O:
Solution:
H2O = 2 hydrogen + 1 oxygen
= 2H + 1O = 2+1 = 3.
Therefore the compound, H2O is triatomic (it contains three atoms).

More Examples:
• Na2CO3.10H2O
Solution:
Note: Whenever there is a number in front of the chemical formula of the compound
i.e 10H2O, that number as infront multiplies the numbers below each of the atoms (i.e
10H2O = [10x2)H + (10x1)O] as shown below:
Na2CO3.10H2O can also be written as Na2C1O3.10H2O1 (Only for the purpose of
calculation)
Na2C1O3.10H2O1 = [2 Sodium + 1 carbon + 3 Oxygen] + [(10 x 2) Hydrogen
+ (10 x 1) oxygen]
= [2 Na + 1C + 3O] + [(10 x 2) H + (10 x 1) O]
= [2 Na + 1C + 3O] + [(20) H + (10) O]
= 2+ 1 + 3 + 20 + 10
= 36.
Therefore the compound, Na2CO3.10H2O has an atomicity of 36.

More Examples:
• Determine the atomicity of each of the following elements:
(a) An element with relative molecular mass of 160 and relative atomic mass of 80.
Solution:
Parameters: Relative molecular mass (RMM) = 160
Relative atomic mass (RAM) = 80
Using the formula: Relative molecular mass (R.M.M)/ Relative atomic mass (R.A.M)
= 160/80 = 2 (Diatomic, Atomicity is 2).
(b) An element with vapour density of 62 and relative atomic mass of 31.
Solution:
Parameters: Vapour density (V.D) = 32
Relative atomic mass (RAM) = 31
Using the formula: (Vapour density x 2)/Relative atomic mass (R.A.M).
= (32 x 2) / 31
= 64/31
= 2.06 (Diatomic, Atomicity is 2).

Class Activity
• Calculate the atomicity of each of the following elements:
• Determine the atomicity of the following:
(a) Na2SO4.10H2O
(b) Fe3
(c) Ca(HCO3)2.
Elements Relative Molecular Mass Relative Atomic mass
W 124 31
X 254 127
Y 80 20
Z 24 12
Elements Relative Vapour Density Relative Atomic mass
A 10 20
B 42 84
C 54 27
D 2 4

Ions
• Definition of Ions:
• An ion is any atom or group of atoms which possess an electric charge.
• Types of Ions
• CATIONS: These are positively charged ions. E.g. Na+, K+, Ca2+, Mg2+, Zn2+ etc.
• ANIONS: These are negatively charged ions e.g. Cl-, S2-, O2-, F-, Br- etc.
• NOTE: An ionic substance has the same number of positive and negative ions, so that it is
electrically neutral.

Valency
• Definition of Valency:
• Valency is the combining power of an element or radical. It is actually the oxidation umber
assigned to the element or group of elements without charge.
• Classification of Valencies
• Monovalent or univalent: this refers to elements with only one valency e.g. Na+, K+, F- etc.
• Divalent – This refers to elements with two valencies e.g. Cu2+, Ca2+, Pb2+, Zn2+, Mg2+, O2-,
Trivalent: This refers to elements with three valencies e.g. Al3+, Fe3+, etc.
• Tetravalent: This refers to elements with four valencies e.g. carbon, silicon etc.
• Variable valencies – This refer to some elements having more than one valency.
• Examples are:
Copper has a valency of 1 or 2; Iron has a valency of 2 or 3; Carbon has a valency of 2 or 4 or
6; Lead has a valency of 2 or 4
• As a result of these variable valencies, they form more than one compounds, e.g. copper
can form copper (i)oxide, CuO and copper (ii)oxide, CuO2. Carbon is also able to form
carbon(ii)oxide, CO and carbon(iv)oxide, CO2.

Four Ways to Determine Valency of an Element
1. From electronic configuration of the element.
2. The group the element belong to on the periodic table.
3. The number of electrons required by the element (non-
metal) to acquire a filled electronic configuration.
4. Determination of Valency from molecular formulae

1. From electronic configuration of the element
• .Electrons of elements are grouped using shells.
• The shells include K, L, M, N, O, P and Q.
• Each shell has its maximum number of electrons it can take determined using the
formula: 2n2.
• The value of n for each shell includes K (1), L(2), M(3), N(4), O(5), P(6) and Q(7).
• Based on the formula 2n2 the maximum number of electrons in K is 2, L is 8 and M is 18.
• Note that the maximum number of electrons that can be outermost shell of an element is
8. Having 8 electrons in outermost shell gives stability to elements and makes them less
reactive, e.g. noble gases. In fact most elements undergo reaction in order to have 8
electrons in their outermost shells.

Electron Configuration of the First 20 Elements
.
Element Symbo
l
Number of Protons (or
atomic number)
Number of Electrons and their Distribution in the Shells
K L M N
Hydrogen H 1 1
Helium He 2 2
Lithium Li 3 2 1
Beryllium Be 4 2 2
Boron B 5 2 3
Carbon C 6 2 4
Nitrogen N 7 2 5
Oxygen O 8 2 6
Fluorine F 9 2 7
Neon Ne 10 2 8
Sodium Na 11 2 8 1
Magnesium Mg 12 2 8 2
Aluminium Al 13 2 8 3
Silicon Si 14 2 8 4
Phosphorus P 15 2 8 5
Sulphur S 16 2 8 6
Chlorine Cl 17 2 8 7
Argon Ar 18 2 8 8
Potassium K 19 2 8 8 1
Calcium Ca 20 2 8 8 2

Difference between Valency and Oxidation Number
• The Combining capacity of an atom is called valency. Thus, it is the number of valence
electron an atom has to gain or lose from its outermost orbit. The oxidation number is the
charge an atom can carry.
• For instance, nitrogen has valency 3 but its oxidation number can range from -3 to +5.
Oxidation number is an assumed charge of a particular atom in a molecule or ion. It
helps to determine the capacity of an atom to gain or lose electrons within a particular
species.

How to Determine Valency From electronic configuration of the element
• Write the electronic configuration of the element and then note the outermost electron of
the element which can then be taken as its valence.
Element Symbol
Atomic
Number
Electronic
Configuration
Valency
Oxidation
number
Carbon C 6 2, 4 2 or 4 +2 or +4
Oxygen O 8 2, 6 2 -2
Neon Ne 10 2, 8 Nil Nil
Sodium Na 11 2, 8, 1 1 +1
Chlorine Cl 17 2, 8, 7 1 -1
Calcium Ca 20 2, 8, 2 2 +2

How to Determine Valency Based on The group the element belongs to.
• In this method, valency is calculated by referring to the periodic table chart. For example,
all the metals, be it hydrogen, lithium, sodium and so on, present in column 1 have
valency +1. Similarly, all the elements present in column 7/17 have valency -1 such as
fluorine, chlorine, and so on. Excemption is elements ith variable oxidation numbers
Group 1 2 3 4 5 6 7 8
Alkali
metals
Alkaline-
earth
metals
Metals Carbon
family
Pnictogen
s
Chalcoge
ns
Halogens Noble
gases
Valencies 1 2 3 2 or 4 3 or 5 2 or 6 1 0
Oxidation
number
+1 +2 +3 +2,+4 -3,-5 -2,+6 -1 0
Elements H H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca

3. From Electron Giving/Taking
The number of electrons required by the element (non-metal) to acquire a filled electronic
configuration or number of electron given before octet state can be attained.

4. Determination of Valency from molecular formulae
The valency of elements and radicals can be determined from the molecular formulae of the
compound in which the element exists. Example if the molecular formula of a compound is
X2Y3;
Therefore, The valency of X = 3
The Valency of Y = 2

Radicals
• A radical is a group of atoms that functions as a single unit in chemical reactions.
Radical Formula Charge Valency
Ammonium NH4
+ +1 1
Hydroxide OH- -1 1
Trioxonitrate (v) NO3
- -1 1
Dioxonitrate (iii) NO2
- -1 1
Trioxocarbonate (iv) CO3
2- -2 2
Hydrogentrioxocarbonate (iv) HCO3
- -1 1
Tetraoxosulphate (vi) SO4
2- -2 2

Chemical Formula
• Chemical formula is the representation of a molecule of a substance using their symbols.
• When an element exists as a molecule, a number representing its atomicity is written as a subscript,
after the symbol of that element, for example, Diatomic hydrogen is written as H2 to show that it
contains two atoms of hydrogen;
• .Writing Formulae from Valencies
Formulae of compounds can be deduced from the valencies of the component elements or
radicals.
• Rules for Writing Chemical Formulae
• Write down the symbol of elements or radicals.
• Write down the positive value of charge elements or radicals.
• Exchange the charges by cross-multiplying
• Write down the chemical formula of the compound.
• NOTE: The subscript 1 is not normally written. Sunday, January 15, 2023

Examples:
• Sodium trioxonitrate (v)
Solution:
Step 1: Write out the symbols of the elements or radicals
Sodium = Na
Trioxonitrate (v) = NO3
Step 2: Write down the valency plus charge of the elements or radicals
Na = +1
NO3 = -1
Step 3: Exchange the valencies of the elements or radicals (the element or valency
with a positive charge should be written first) as shown below:
NaNO3

Examples:
• Ammonium tetraoxosulphate (vi)
Solution:
Step 1: Write out the symbols of the elements or radicals
Ammonium = NH4
Tetraoxosulphate (vi) = SO4
Step 2: Write down the valency plus charge of the elements or radicals
NH4 = +1
SO4 = -2
Step 3: Exchange the valencies of the elements or radicals (the element or valency
with a positive charge should be written first) as shown below:
(NH4)2 SO4
Class Activity:
1. Calcium trioxocarbonate (iv)
2. Copper (ii) tetraoxosulphate (iv). Sunday, January 15, 2023

Evaluation
• Define atom with examples
• Define atomicity with examples
• Define ions with examples
• List and explain the types of ions
• Define molecules with examples
• Explain valency and its classification with examples
• Explain radicals with examples

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