BEFORE YOU START

You are expected to KNOW the ATOMIC

NUMBER of the FIRST 20 ELEMENTS.
This WILL NOT be provided to you.

Introduction to Chemistry
Definition Of Chemistry
-​ A branch of science that studies the substances that
everything is made up of. Investigate the properties of
matter, the atoms they are composed of and how
these atoms react to make new substances.

**Matter is anything that has mass and takes up space

(volume).
Main Branches of Chemistry
Physical Chemistry
-​ The branch of chemistry dealing with the relations
between the physical properties of substances
and their chemical composition and
transformations.
-​ Investigate how atoms come together to create
compounds and molecules as well as the energy
changes that occur during a chemical reaction.
-​ A physical chemist may study the rates of chemical
reactions, the energy transfers that occur in reactions,
or the physical structure of materials at the molecular
level.

Organic Chemistry
-​ Organic chemistry is the study of the structure,
properties, composition, reactions, and preparation of
carbon-containing compounds.

Inorganic Chemistry
-​ Inorganic chemistry is concerned with the properties
and behavior of inorganic compounds (substances
that are not carbon-based), which include metals,
minerals, and salts.
-​ They are commonly found in rocks and minerals.
Analytical Chemistry
-​ It is the study of the chemical composition of
matter.
-​ It focuses on the separation, identification and
quantification of specific compounds (chemicals)
in samples of matter.
-​ An analytical chemist may use complex instruments
to analyze an unknown material, in order to
determine its various components.

Biochemistry
-​ It is the study of chemical processes that occur in
living things.

Summary of the Branches of Chemistry

ACTIVITY: Match the project with the correct
chemistry discipline (homework)

Project Branches of Chemistry

Activity
List 5 things at home that shows chemistry in your
everyday life
1
2
3
4
5

Answer
Chemistry In Our Everyday Lives
Examples include:
-​ Cooking - e.g baking, frying, boiling etc.
-​ Cleaning solutions e.g bleach, soap etc
-​ Medicines
 -​ Global Warming

Other Areas of Science That Overlaps With Chemistry

Examples include:
-​ Biology
-​ Physics
-​ Forensics
-​ Agriculture

Chemists And Their Contributions/Achievements in

Chemistry (Student Activity - Homework)- P. 193 in text
book (Grade 9 Sciences for Jamaica)
1.​
2.​
3.​
4.​
5.​

Careers That Requires Chemistry

Examples include:
-​ Quality control chemist
-​ Lab technician
-​ Researcher
-​ Educator
Know Lab Rules
1.​Do not eat in the lab
2.​ Do not drink in the lab
3.​ Do not play in the lab
4.​ Do not taste any substance seen in the lab
5.​ Do not conduct unsupervised experiments in the lab
6.​ Do not Run about in the lab
7.​ Do not turn the gas tap
8.​ Never enter the preparation (prep) room without
permission
9.​ Never throw solids down the drain (e.g. paper)
10.​ Never hold hot containers with the bare hands
11.​ Never enter the lab unless a teacher is present
12.​ Never put bags or books in the work area
13.​ Never push anything into the electrical outlet
14.​ Always pay attention to all instructions given
15.​ Always report all accidents no matter how small
they may seem.
16.​ Always hold containers by the neck and the bottom
17.​ Report all chemical spills and laboratory accidents
to your teacher immediately.
18.​ Always clean up spillages promptly.
19.​ Wear long hair tied back to avoid catching fire or
other accidents.
 20.​ Wear safety gear when working in the lab e.g. lab
coat, safety goggles and enclosed shoes
21.​ Do not taste or smell chemicals unless instructed
to do so by your teacher.
22.​ Keep work station clean and uncluttered.

YouTube Video On Safety Gear (Goggles, Lab Coat, and

Gloves)
https://youtu.be/KIqH3oqJk0M

Know Apparatus and Materials

-​ Identify/ name it
-​ Its use
-​ Draw it

YouTube Video On Some of the Laboratory Equipment

https://www.youtube.com/watch?v=Bp2DI32X4wE

COMMON LABORATORY EQUIPMENT

NAME Description and/or use Picture

 Glass container, most are pyrex; common sizes are
100 ml, 25 ml, 400 ml; it can be used as a
BEAKER
container, shows approximate volume, and may
be heated

A metal heating device connected to a gas outlet

with rubber tubing; used to heat chemicals in
BUNSEN BURNER
beakers or test tubes; has adjustable air-hole
allowing some control of temperature

It is marked with a milliliter scale and fitted with a

BURETTE stopcock; can be used to withdraw and measure
accurate volumes of solutions in titrations

Metal with rubber ends; used to handle hot

BEAKER TONGS
beakers

Chemical resistant rubberized apron used to

CHEMICAL APRON
protect clothing

Made of porcelain; used to heat small amounts of

CRUCIBLE & COVER solid substances that are being heated strongly at
high temperatures

Metal utility tongs used for hot crucibles;

CRUCIBLE TONGS
spring-like jaws with a jaw opening

Glass tip with a rubber bulb; used to transfer

DROPPER
small amounts of liquids
ELECTRONIC
Used for quick, accurate massing
BALANCE

Container; common sizes are 125 ml, 250 ml, 500

ERLENMEYER FLASK / ml; may be heated; it has a thin neck and a wide
Conical Flask base; used to hold liquids when carrying out
reactions and preparing solutions

Porcelain dish; used to hold a solution whose

EVAPORATING DISH solvent is being separated from the solvent by
evaporation (often using heat)

Used to hold liquids when carrying out reactions

FLORENCE FLASK (no heat use flat-bottomed; even heating required
use round-bottomed)

Metal or plastic, straight-tipped instrument used

FORCEPS
to isolate and remove small particles

Made of glass or plastic; used to hold a filter

FUNNEL
paper and can be used in pouring (to avoid spills)

GOGGLES Used to protect eyes

GRADUATED Marked with milliliter (ml) scale and is used to
CYLINDER measure volume

HEAT RESISTANT Used to handle hot glassware or other hot lab

GLOVES equipment

Heavy porcelain dish with grinder; used to grind

MORTAR & PESTLE chemicals to a powder

PIPESTEM TRIANGLE Triangular wire frame with clay material coverings;

(CLAY TRIANGLE) used to support a crucible

DROPPING
Used to transfer small amounts of liquid
PIPETTE

PLASTIC WASH Squeezable plastic bottle; used to dispense

BOTTLE distilled water

Iron ring with screw fastener; comes in several

RING CLAMP (IRON
sizes; used to fasten to the ring stand as a support
RING)
for an apparatus
RING STAND Metal rod that is upright and sits on a heavy base;
(SUPPORT STAND) used as a support and has many uses

Used to cap the openings of glassware such as

RUBBER STOPPER
test tubes or Erlenmeyer flasks

Made of metal; has a flat rounded end and a

SPATULA
rectangular end; used to transfer solid chemicals

Made of glass; used to stir combinations of

STIRRING ROD
materials

Made of metal and has a flint; used to ignite the

STRIKER
Bunsen burner

Glassware that comes in many sizes; it has many

TEST TUBE
uses and can be heated

Brush with wire handle; used to scrub thin

TEST TUBE BRUSH
glassware

Metal clamp with a screw fastener, a swivel and

lock nut, an adjusting screw, and a curved clamp;
TEST TUBE CLAMP
used to hold an apparatus (test tube or burette)
to the ring stand
 Made of metal; has a clamp with a spring handle;
TEST TUBE HOLDER
used to hold a test tube

May be made of wood, metal, or plastic; used to

TEST TUBE RACK
hold test tubes in an upright position

Made of glass and filled with a red or blue liquid

THERMOMETER
(usually alcohol); used to determine temperature

TRIPLE BEAM Used for determining the mass, in grams, of a

BALANCE chemical or object

Used when mixing accurate concentrations of

VOLUMETRIC FLASK solutions. Each flask has a volume marking which
is very exact and can be stoppered.

Curved glass; may be used as a beaker cover or for

WATCH GLASS
evaporating very small amounts of liquid

Small plate with several wells; used for reacting

WELL PLATE
small amounts of chemicals
 Wire screen with ceramic fibered center; used to
WIRE GAUZE
spread the heat of a flame

THE HISTORY OF THE ATOM:

Theories and Models

YT Video: The History Of The Atom

-​ https://youtu.be/v48u8hjqNBU

(you can watch the whole video if you want)

Watch Time Stamp: 1:33 - 3:55
-​ https://youtu.be/pmUhkQjHr3A
Dalton’s Atomic Theory

1.​All matter consists of indivisible particles called

atoms.
2.​Atoms of the same element are identical in shape,
mass and properties but differ from the atoms of
other elements.
3.​Atoms cannot be created or destroyed (the law of
conservation of mass).
4.​Atoms of different elements may combine with
each other in a fixed, simple, whole number ratios
to form compounds (e.g. H2O).
5.​The atom is the smallest unit of matter (cannot be
divided into smaller particles) that can take part in
a chemical reaction.
6.​Atoms can be separated, rearranged and combined
in a chemical reaction.

YT Video: Atomic Theory

https://youtu.be/syi3pXJNe58
Definition of An Atom
-​ The smallest particle of an element that can exist on
its own and still have the properties of that element.

Definition of Element
-​ An element is a pure substance made up of one
type of atom. All atoms of any one element are the
same. E.g He, Au (an element that can exist as an
individual atom) N2 (element that exist as a molecule)

Definition of Compound
-​ A pure substance that contains two or more
different types of element which are chemically
bonded in such a way that their properties change.
-​ Compounds are composed of more than one kind of
atom which will always be in the same proportion by
mass. (e.g water H2O)

Definition of Molecules
-​ A molecule is a group of two or more atoms which
are covalently bonded together strongly enough to
behave as a single unit in a chemical reaction e.g
H2O (e.g. of a compound that’s a molecule) , O2 (e.g
of an element that’s a molecule)
Atomic structure
Matter is anything that has mass and occupies space.

All matter is composed of tiny particles. Atoms are the

most basic (smallest) particles.

Definition of An Atom
-​ The smallest particle of an element that can exist on
its own and still have the properties of that element.

General diagram of an atom

What is the mass # and the atomic number of the atom
above?

What is the mass # and the atomic number of the atom

above?

Subatomic particles (smaller than an atom)

1. Protons (p)
2. Neutrons (n)
3. Electrons (e)
 Comparing protons, neutrons and electrons
subatomic relative mass relative location
particle (a.m.u. - atomic charge
mass unit)
Proton 1 1+ nucleus
Neutron 1 0 nucleus
Electron **1/ 1840 = 0 1- Shells/ energy
levels
**mass of an electron is considered negligible

*The nucleus is positively charged and the electrons are

negatively charged therefore there's an attraction between
the two.
Notation of an Atom (Basic)

Calculations
1.​ Mass# (nucleon #) = # of protons + # of neutrons

2.​ Atomic # (Proton #) = # of protons

3.​# of protons = # of electrons

(applies only to atoms)

*all atoms are neutral (they carry no charge/ no net

charge/ no overall charge) because they have equal
number of protons as electrons

4.​ # of neutrons = mass# - # of protons

YouTube Video on Atomic Structure & Atomic Mass

 1.​https://youtu.be/8NuSzMIsir0

2.​https://youtu.be/fN8kH9Vvqo0

Example: Helium Atom

Calculate the number of protons (p), neutrons (n),

electrons (e) & overall charge/ net charge for the
helium atom
Element(s) # of sub atomic Overall
Mass Atomic particles charge
# # #p - #e
Name Symbol p n e
Helium He 4 2 2 4-2=2 2 2-2=0

Example
Calcium: mass# = 40 atomic # = 20
P = 20
N = 40 - 20 = 20
E = 20

Example
Potassium: mass# = 39 atomic# = 19
P = 19
N = 39 - 19 = 20
E = 19

Example
Fluorine: mass# = 19 atomic# = 9
P=9
N = 19-9=10
E=9
Shells/ Energy levels
-​ electrons orbit the nucleus at fixed distances from the
center of the atom in areas called shells
-​ each shell has a fixed number of electrons
-​ The last shell (outermost shell) of an atom is called
the valence shell. The electrons on this shell are
called valence electrons.

Electronic configuration
-​ The arrangement of electrons on the shells of an
atom.
Link between an electron shell and the maximum
number of electrons it can hold

DO NOT NEED TO KNOW

Electron Shell Maximum number of
electrons it holds
1 (innermost shell/ closest 2
to the nucleus)
2 8
3 18 (8 then 10)
4 32 (8 then 10 then 14)

THIS IS WHAT YOU NEED TO KNOW

Electron Shell Maximum number of
electrons it holds
1 (innermost shell/ closest 2
to the nucleus)
2 8
3 8
4 8
 -​ The shell closer to the nucleus (inner shell) must
contain the maximum number of 2 electrons
before filling the next energy level.

Steps on How to Draw Atom

-​ DO NOT PUT ELECTRONS ON THE NUCLEUS.
-​ When putting on electrons START with the shell
CLOSEST to the nucleus
-​ Add electrons one at a time before pairing them up.
-​ Electrons are represented with a dot (・) or a cross (╳).
-​ Protons (P), neutrons (N) and electrons (E) must
always be rounded up or down to the nearest whole
number (there is no such as a piece of a proton,
electron or neutron)

Examples of Drawing Atoms

Example 1: Sodium Atom (TEACHER’S)
Example 2: Oxygen Atom (TEACHER”S)
(- Green tick: shows the RIGHT way to put on electrons -
Single then pair them.
-​ Red cross shows: shows the WRONG way to put
electrons on.)
Example 3: Sulphur Atom (STUDENT)
Example 4: Argon Atom (STUDENT)

Isotopes
Definition:
-​ Different atoms of the same element which have the
same number of protons but different number of
neutrons. (They have the same atomic number but
different mass number)
 -​ Notes: they have the same number of electrons.

Examples of Isotopes
DO NOT NEED TO KNOW HOW CALCULATE
Calculate the relative atomic mass of chlorine, if 75%
exists as chlorine-35 and 25% exists as 37Cl.

[(75/100) x 35] + [(25/100) x 37]

= 26.25 + 9.25

= 35.5
YouTube Atomic Mass & Isotopes
https://youtu.be/8NuSzMIsir0

YT Video: Isotopes & Isobars (DO NOT LOOK AT

ISOBARS)
https://youtu.be/qgJW1g0nCxQ
Watch from 0:00 - 2:44

Periodic Table

YT VIDEO: History of The Periodic Table

https://youtu.be/ogpWoB4m-Ns

History of the Periodic Table

Johann Dobereiner (1780-1849) – The Law of Triads
Dobereiner’s Triads - groups of three elements
eg Li Na K, Cl Br I
Rule: the atomic mass of the middle element is the
average atomic mass of the other two elements.
Since all triads did not obey this rule, they decided it was
not useful.

John Newlands (1837-1898) – Law of Octaves

Placed elements in order of increasing atomic mass.
​ Rule: The 8th element, starting from a given one, is a
kind of repetition of the first, like the 8th note in an octave
of music
​ Found the pattern of periodicity but it only worked for
the first 16 elements. Did not account for elements not
discovered yet.
​ Still needs improvement.

Dmitri Mendeleev (1834-1907) – The Periodic Table

- Greatest credit to the design of the periodic table
- Increasing atomic mass
- Regularly repeating pattern of properties
- Left spaces in table for unknown elements

Periodic Table
Periodic - recurrence at regular intervals

-​ The arrangement of all the known / discovered

elements in the table according to their increasing
atomic numbers (by 1) and in relation to their
electronic configuration.

-​ The elements are arranged / classified according to

the similarities in their chemical properties (Metals
vs. Non-metals)

-​ Each square contains the element’s name, symbol,

and two numbers (mass number and atomic number)
 -​ Explain to students how symbols on periodic table.
Can have one capital letter e.g. C - Carbon, N -
Nitrogen etc. or have One capital letter followed by a
common letter e.g. Au - Gold, He - helium etc.

-​ It is similar to other tables as it is read from left to

right and is made up of rows and columns.

Parts of the Periodic Table

Metals
With the exception of hydrogen, the elements on the
left-hand side (LHS) of the periodic table are metals.
Table showing GENERAL PHYSICAL PROPERTIES of metals

Physical Properties Metals

Melting & Boiling points Usually high
State at room temperature Solid (except mercury)
Appearance of the solid Shiny
Bendability of the solid Malleable & Ductile
Density Usually high
Electrical & Thermal conductivity Good

The two rows of elements below the body of the periodic

table are metals. Specifically, they are a collection of
transition metals that are called the lanthanides and
actinides or the rare earth metals. These elements are
located below the table because there wasn't a practical
way to insert them into the transition metal section without
making the table look strange.

Metalloids (or Semimetals)

There is a zig-zag line/ step-line toward the right side of
the periodic table that acts as a sort of border between
metals and non-metals. Elements on either side of this
line exhibit some properties of metals and some of the
nonmetals. These elements are the metalloids, also
called semimetals. (Can also look at the image of the
periodic table posted in google classroom to see where the
zig-zag begins and ends).

Non-metals
The elements on the right-hand side (RHS) of the
periodic table are the nonmetals.
Table showing GENERAL PHYSICAL PROPERTIES of non-metals

Physical Properties Non-metals

Melting & Boiling points Usually low
State at room temperature Can be solid, liquid or gas
Appearance of the solid Dull
Bendability of the solid Brittle
Density Usually low
Electrical & Thermal conductivity Poor (except graphite)

Groups/ Column (vertical)

-​ there are eight (8)
-​ numbered using Roman numerals (I,II, III, IV, V, VI, VII,
VIII/ 0).

Periods / Rows (horizontal)

-​ there are seven (7)
-​ numbered using cardinal numbers (1, 2, 3, 4, 5, 6, 7)

The Extended Periodic Table

-​ Transition metals
 -​ placed between group II (2A) and group III (3A)

-​ Lanthanide Series
-​ rare earth metals
-​ naturally found in Earth

-​ Actinide Series
-​ Radioactive, metallic, some are not found in
nature and are created in labs

Trends (Patterns) in the Periodic Table

Groups (going down)

-​ All the elements in a group have similar chemical
properties and are a ‘chemical family’. Members
of the family/ group are similar but not the same.

-​ Some groups have a special name.

o​ Group I – Alkali Metals
 o​ Group II – Alkaline Earth Metals
o​ Group VII – Halogens
o​ Group VIII or 0 – Noble Gases
o​Metals found between Groups IIA and
Group IIIA - Transition Metals

-​ As you go down the group, each element has one

more electron shell than the previous element. All
elements in a group have the same number of
electron(s) in its last shell (valence electrons).

E.g. All the elements in Group I have only one

electron in their outermost shell or one valence
electron. Group II elements have two valence
electrons and so on…All the elements in Group
VIII/ 0 have a full outermost shell of electrons and
are considered noble gases. Only Helium does not
have eight electrons in its outermost shell.

-​ General rule:
Elements in Groups I, II, and III are metals except
H and B.

NOTE:
**Although hydrogen, H is in group 1, it is a
non-metal
**Although Boron, B is in group 3 it is a metalloid.

Elements in Groups IV – VIII are non-metals.

Periods (going across)
-​ Elements of one period all have the same number
of electron shells.
Therefore, if an element is in period 1, it only has
one (1) electron shell
Example: H - E.C. 1 He - E.C. 2
Therefore, if an element is in period 3, it only has
three (3) electron shells
Example: Na - E.C. 2, 8, 1 Si - E.C. 2,8,4

-​ Each element has one more proton and one

more valence electron than the previous one (as
you go across the period).
Example: Li- 2,1 Be- 2,2 B- 2,3

-​ As you go across the period elements go from

metals to non-metals. Elements' chemical
properties change from metallic to non-
metallic.
 How to use the Group Number and The Period
Number to Determine the Location of the of an
Element (Similar to coordinates longitude and latitude
on a map) on their own

Group Period Electronic Element

Number Number Configuration
1A 1 1 Hydrogen, H
3A 2
2, 8, 4
Sodium, Na

Answers
Group Period Electronic Element
Number Number Configuration
1A 1 1 Hydrogen
3A 2 2,3 Boron, B
4A 3 2, 8, 4 Silicon
1A 3 2,8,1 Sodium, Na
 TRENDS
Specific observable patterns in the properties (e.g boiling point,
melting point, atomic radii etc.) of the chemical elements of the
periodic table.

-​ Periodic Table - Trends

Groups Properties
Group 1 – Alkali Metals -​ Very soft metals. Cut with knife.
*Note: Hydrogen is not metal -​ Have low densities (will float on water).
Lithium, Li -​ Very low melting points.
Sodium, Na -​ Very reactive with air and water.
Potassium, K -​ Produce salts when reacted with
Rubidium, Rb non-metals.
Caesium, Cs
-​ Reactivity increases as you go down
Francium, Fr
the group (Francium is the most
reactive metal).
-​ Melting point decreases as you go
down the group
-​ Conducts electricity
Group 2 – Alkaline Earth Metals -​ Have low densities but do not float on
Beryllium, Be water.
Magnesium, Mg -​ Easily tarnished in air but not as
Calcium, Ca reactive as group 1 metals.
Strontium, Sr -​ Harder than group 1 metals.
Barium, Ba -​ Not strong, but forms alloy with other
metals which increases their strength.
-​ Produce brilliant colours when heated.
-​ React with non-metals to form salts.
-​ Have higher melting points than group
1 metals.
-​ Conduct electricity
Group 7 - Halogens -​ Elements change from being gas to
Fluorine, F solid as you go down the group.
Chlorine, Cl -​ Fluorine – pale yellow - gas
Bromine, Br -​ Chlorine – yellow-green - gas
Iodine, I -​ Bromine – red-brown - Liquid
-​ Iodine – black - solid
-​ Exist as diatomic molecules e.g. Cl2, I2
-​ They are poisonous and have a sharp
smell
-​ The melting point and boiling point
increases as you go down the group
-​ Density increases as you go down the
group
-​ Reactivity increases as you go up the
group (fluorine is the most reactive) -
e.g displacement reactions (explain
how this works to students)
Group 8 – Noble Gases/ Inert Gases -​ Colourless, odorless gases found in
Helium, He air.
Neon, Ne -​ Unreactive (inert) because they have a
Argon, Ar full valence shell
Krypton, Kr -​ Low densities
-​ Low boiling points
-​ Do not burn (non-flammable)
Transition Metals -​ High melting point but mercury is a
Examples: liquid at room temperature
Copper, Cu -​ Very dense (high densities)
Iron, Fe -​ Shiny
Gold, Au -​ Malleable (can be hammered into
sheets)
-​ Ductile (can be drawn out into wires)
-​ Good conductors of electricity and
heat
-​ Less reactive than alkali metals
-​ Usually hard
-​ form coloured compounds
-​ display multiple oxidation states e.g.
Cu+ or Cu2+ or Fe2+ or Fe3+
Explanation for Increase in Reactivity (ease of
ionization - lose valence electrons) as you Go Down
Group 1 (Alkali Metals). (This explanation also applies to Group 2
(Alkaline earth metals)). ***However, out of all the metals, Francium is the most
reactive metal. ***Group two metals are less reactive than group 1 metals.
Explanation for Increase in Reactivity (ease of
ionization - gain electrons) as you Go Up Group 7
(Halogens)
Activity associated with:
Trends in Group 2, 7 and Period 3.
INSTRUCTIONS
1.​Fill out the missing information in the table.
2.​Observe and describe the trends in each property as
you go down the Alkali earth metal group, Halogens
and as you go across Period 3.
3.​Write out each of the statements written on the
opposite side, completing each statement with the
observed trend (increase or decrease)

Definition of terms:
Atomic radius - measures size of atom, distance from
nucleus to the energy shells.
Electronegativity - tendency of an atom to attract a
bonding pair of electrons.
Ionization - Atoms can lose or gain electrons to form
charged particles called ions (cations or anions). When
they lose or gain electrons, they are said to have been
ionized.
**The easier an element ionizes (become a cation or
 anion), the more reactive it is.**

First Ionization energy - amount of energy required to

remove the most loosely held electron from an atom to
form corresponding ions with a 1+ charge (atoms and ions
are to be in a gaseous state).
**ALL elements have a first ionization energy**

Group 2 Elements
Symbol Atomic Number of Atomic First Electronegativity Melting
number shells radii/p Ionization Point/0C
m Energy/kJ
mol-1
Be 112 899 1.57 1280
Mg 160 738 1.31 651
Ca 197 590 1.0 851
Sr 215 549 0.95 800
Ba 217 503 0.89 850
Ra 283 509 0.89 960

Down a group atomic radius tends to _____________________.

Down a group first ionization energy tends to _______________.
Down a group electronegativity tends to ________________.
Down a group melting point tends to _________________.
Down a group reactivity (based on first ionization energy) tends to
____________________
 Group 7 Elements
Symbol State Colour Atomic Number Atomic First Ionization Electronegativit Melting
number of radii/pm Energy/kJmol-1 y Point/0C
shells
F gas 42 1681.0 4 -220
Cl gas yellow- 79 1251.2 3.2 -101.5
green
Br liquid Red- 94 1139.9 3 -7.35
brown
I solid black 115 1008.4 2.7 113.7

Down a group atomic radius tends to _____________________.

Down a group first ionization energy tends to _______________.
Down a group electronegativity tends to ________________.
Down a group melting point tends to _________________.
Down a group reactivity (based on first ionization energy) tends to
____________________

Period 3 Elements
Symbol Na Mg Al Si P S Cl Ar
EC
Metal/non-metal
Atomic 166 141 121 111 107 105 102 106
radius/pm
First Ionization 496 738 578 787 1012 1000 1251 1521
-1
energy/ kJmol
Melting Point/0C

Across a period atomic radius tends to _______________.

Across a period first ionization energy tends to _________________.
Across a period electronegativity tends to ___________________.
Across a period reactivity tends to ___________________.

Pure Substances & Mixtures

Matter can be classified into two main groups:
(i)​ pure substances
(ii)​ Mixtures (impure substances)

Pure Substances
-​ Are composed/ consists of one type of material.
-​ They have the following properties:
​ Fixed/ constant melting, boiling and freezing point
(impurities lower the melting point and raises
the boiling point of a pure substance).
​Constant density
-​ Can be further classified into elements and
compounds.

Elements
-​ A pure substance that cannot be broken down into
any simpler substance by any chemical or physical
means.
-​ They are composed of only one kind of atom.
​Individual atoms (smallest particles into which an
element can be divided) e.g. Argon, Ar or Gold,
Au
 ​Molecules (groups of atoms bonded together)
e.g. Oxygen, O2

Compounds
-​ A pure substance that contains two or more different
types of element which are chemically combined
(bonded) in such a way that their properties change.
-​ Composed of more than one kind of atom, which will
always be the same (fixed) proportions by mass.
e.g. water, H2O (a covalent compound which is a
molecule); sodium chloride, NaCl (an ionic
compound)

(not true
structure of NaCl. simplified version)
 -​ Introduce to students what formula writing is about.
E.g. H2O - 2 hydrogens, 1 oxygen

How to Make a Compound from Different Elements

e.g. Magnesium + oxygen 🡪 magnesium oxide
(element) (element) (compound)
2 Mg(s) + O2(g) → 2MgO(s)

Mixtures
Definition:
A type of matter where components are not chemically
combined and can be separated by physical means.

-​ The component parts are not in a fixed ratio and they

retain their physical properties.
-​ Consists of two or more substances (elements/
compounds) combined together in varying
 proportions. Each component retains its own
independent properties and has undergone no
chemical reactions with any other substance in the
mixture.
-​ Can have a mixture of: (i) elements (ii) compounds
(iii) mixture of elements and compounds.

Homogeneous Mixtures e.g. a solution of sodium

chloride in water
-​ The properties and composition are uniform
throughout the sample

Heterogeneous Mixtures e.g. mixture of sand and

water
-​ A non-uniform mixture. This includes suspension and
colloids.
-​ The components do not dissolve into each other.

Solutions, Suspensions, Colloids

Solution e.g. a mixture of salt (solute) and water
(solvent)

Definition:
A solution is a homogeneous mixture of two or more
substances; one substance is usually a liquid.
 -​ A homogeneous mixture containing one or more
solute dissolved in a solvent.
-​ a mixture that is uniform and has the same
composition throughout.
-​ It Is formed when one substance called a solute
dissolves in another called a solvent.
-​ Light can pass through them.
-​ Have two components:

1. Solute - minor component of a solution

-​ the substance which dissolves and
its presence in a lower
concentration
2. Solvent - major component of a solution
​ ​ ​ ​ - does the dissolving and present in
highest concentration

** The solute and solvent can either be gases, liquids or

solids.

**All gaseous mixtures are solutions.

** When a gas or a solid dissolves in a liquid, the liquid is

always the solvent.
** Solutions in which water is the solvent are called
aqueous solutions. Solvents other than water are called
non-aqueous solvents ( usually organic).

Suspension
-​ A heterogeneous mixture where minute but visible (to
the naked eye) particles are dispersed in another
substance, usually a liquid. If left undisturbed, the
particles eventually settle.
-​ It appears cloudy.
-​ The particles cannot pass through filter paper.
-​ e.g. muddy water

Colloid
-​ Heterogeneous mixtures which have properties
somewhere between that of a solution and a
suspension.
-​ A mixture containing particles intermediate in size
between those of a solution and a suspension. The
particles of a colloid cannot be seen with the naked
eye and if left undisturbed they will not settle.
-​ A colloid scatters light.
-​ E.g. toothpaste, milk

Size of Particles Increasing

Solution → colloid → suspension

Class Activity
Students are to Identify which drawings are element,
compound, mixture of elements, mixture of compounds,
mixture of elements and compounds.

Answer to the questions above

A - Mixture of elements
B - One compound only - a pure substance
C - One compound only - a pure substance
D - One element only (a molecule) - a pure substance
E - One element only (an individual atom e.g. He gas) - a
pure substance
F - mixture of compounds
G-
H - One element only (pure substance e.g. Au metal)
I-

Pure Substance and Mixtures, Elements &

Compounds
https://www.youtube.com/watch?v=OHhnm2p5G3o
Time Stamps to watch this video:
1.​ 0:00 to 9:47
2.​ 11:48 to End

You Tube Video: Mixtures and solutions (everyday

examples)
https://youtu.be/7Vh_tL67FLY
Chemical Bonding
-​ A linkage formed between two or more atoms which results in each
atom acquiring a more stable state.

Types of Bonding:
1.​ Ionic Bonding (metal + non-metal) - transfer of electrons
2.​ Covalent Bonding (non-metal + non-metal) - sharing of electrons
3.​ *Metallic bonding (pure metal OR metal + metal)

Octet rule
-​ Many elements tend to gain, lose or share electrons until they have
achieved a valence shell that contains 8 electrons like noble
gases.
*Noble gases are very stable.
Ionic Bonding
Ion Formation (Ionization)
-​ Atoms are neutral
-​ Ions are charged particles.
An atom loses or gains electrons.
-​ Cations are positively charged ions
-​ Metals become cations when they lose electrons
-​ Anions are negatively charged ions
-​ Non-metals gain electrons and become anions

YouTube Video on ATOMS / IONS

1.​https://youtu.be/fN8kH9Vvqo0
Formation of Ions (Ionization)
CATIONS
Example: Magnesium (TEACHER)
EQUATION: Mg - 2e- → Mg2+
Example: Sodium (STUDENT)
EQUATION: Na - 1e- → Na+
 ANIONS
Example: Oxygen (TEACHER)
EQUATION: O + 2e- → O2-
Example: Chlorine (STUDENT)
EQUATION: Cl + 1e- → Cl-