Physical Science
Study of Matter
at the Atomic Scale
PHYSICS
BIOLOGY
CHEMISTRY
(central science)
EARTH SCIENCE
ENVIRONMENTAL
(APPLIED)
ENGINEERING
(APPLIED)
MEDICINE
(APPLIED)
Chemistry is the study of
CHANGE
Chemistry is the study of matter
and the changes it undergoes.
OBSERVATIONS
- the action or process of observing something or
someone carefully or in order to gain information.
Can be observed using the
sense of sight.
Can only be observed using
special equipment.
MACROSCOPIC
MICROSCOPIC
MACROSCOPIC
MICROSCOPIC
The macroscopic world is
everything observable.
The microscopic world deals
with the things that our eyes
cannot observe. This is where
the different laws in
Chemistry comes in.
A macroscopic property
describes characteristics or
behavior of a sample which
is large enough to see,
handle, manipulate, weigh,
etc.
A microscopic property
describes the behavior of a
much smaller sample of
matter, an atom or molecule
for instance.
ALCHEMY
universal
solvent that will
turn every
metal to gold
elixir of life
(immortality)
MODERN
CHEMISTRY
discovery of
elements
experimentation
Theories can help us make better
predictions.
Dmitri
Mendeleev's
Theory of the
Periodic Table
predicted
several
undiscovered
elements.
Chemistry in Daily Life
WHY ONIONS MAKE YOU CRY
• Amino acid sulfoxides form
sulfenic acids after you slice
into an onion.
• This gas reacts with the
water in your tears to
form sulfuric acid. The
sulfuric acid burns,
stimulating your eyes to
release more tears to wash
the irritant away.
WHY ICE FLOATS
• As water cools below
4 degrees C, the hydrogen
bonds adjust to hold the
negatively charged oxygen
atoms apart.
• This produces a crystal lattice,
which is commonly known as
'ice'.
• Ice floats because it is about
9% less dense than liquid
water.
WHY ICE FLOATS
BAKING SODA MAKE FOODS RISE
• Baking soda is pure sodium
bicarbonate.
• When baking soda is
combined with moisture and
an acidic ingredient, the
resulting chemical reaction
produces bubbles of carbon
dioxide that expand under
oven temperatures, causing
baked goods to expand or
rise.
CHEMISTRY OF LOVE
• The emotions that you feel are a
result of chemical messengers,
primarily neurotransmitters.
• Researchers say this is due to the
dopamine, norepinephrine and
phenylethylamine we're releasing.
• Dopamine is thought to be the
"pleasure chemical," producing a
feeling of bliss.
• Norepinephrine is similar to
adrenaline and produces the racing
heart and excitement.
USING SUNSCREEN
• Sunscreen combines
organic and inorganic
chemicals to filter the light
from the sun so that less of
it reaches the deeper
layers of your skin.
• The reflective particles in
sunblocks usually consist of
zinc oxide or titanium
oxide.
Chemists ask questions.
Chemistry is full of unanswered questions. One of
the first questions people have been asking since
ancient times is:
“What is the world made of?”
Atomic Theory and the
Basic Laws of Matter
ANCIENT IDEAS ABOUT MATTER
Greek philosopher Democritus
introduced the idea of the atom as the
basic building block matter.
atomos = indivisible
Aristotle thought that all materials on
Earth were not made of atoms, but of
the four elements, Earth, Fire, Water,
and Air. (Elements are mystical
substances).
ANCIENT IDEAS ABOUT MATTER
Robert Boyle wrote a book called the
"Skeptical Chemist”.
His book urged chemists to abandon
the view that elements are mystical
substances.
Instead he promoted a philosophy
that valued observation and
experimentation.
Dalton’s Atomic Theory (1808)
John Dalton was an English chemist,
physicist, and meteorologist. He is best
known for proposing the modern atomic
theory, and for his research into color
blindness, sometimes referred to as
Daltonism in his honor.
Dalton's atomic theory was the first
complete attempt to describe all matter
in terms of atoms and their properties.
1
Elements are
composed of
extremely small
particles called atoms.
To make diagrams
simpler we often
draw atoms as
circles.
- indivisible
- indestructible
- extremely small
- hard spheres
The atoms of one element are
different from the atoms of all other
elements.
2
All atoms of a given
element are identical,
having the same size,
mass and chemical
properties.
Gold is a yellowish solid, iron is a silvery solid, while
mercury is a silvery liquid at room temperature.
Law of Conservation of Mass
3
When matter undergoes
changes, whether
physical or chemical, the
atoms are merely
rearranged.
No atom is created nor
destroyed.
mass of the reactants = mass of the products
The reaction shown is a combustion reaction: a
compound reacts with oxygen and produces
carbon dioxide and water.
Law of Conservation of Mass
The reaction shown is for the formation of water: hydrogen and
oxygen reacts with each other to produce water.
Law of Conservation of Mass
16 X
+
8Y
8 X2Y
29
Law of Multiple Proportion
4
In any compound, the
ratio of the numbers of
atoms of any two of the
elements present is
either an integer or a
simple fraction.
Compounds are composed of atoms of
more than one element.
2 : 16
2 : 32
1:8
1 : 16
Law of Multiple Proportions
Since atoms are
indivisible, they will
always combine in
simple whole number
ratios.
Therefore, it would not make sense to
write a formula such as
Na(0.5)Cl(0.5)
because you can't have half of an atom!
Atomic Structure and Subatomic particles
Subatomic Particles
Subatomic Particles
Atoms, Molecules and
Ions
ATOMS vs MOLECULES
An atom is smallest
particle in an element
that has the properties
of the element. It is not
possible to breakdown
the atom further.
Molecules are formed by
the combination of two
or more atoms. The
atoms are bonded
together in a molecule.
Atoms and Molecules
A heteronuclear diatomic
molecule is a combination of two
atoms of different kind.
diatomic elements
HCl
CO
NaCl
A homonuclear diatomic
molecules contains only two
atoms of the same kind.
H2, N2, O2, Br2, F2, Cl2, I2
A polyatomic molecule contains
more than two atoms.
O3
H2 O
NH3 CH4
Atomic number and Mass number
Mass number (A) = number of protons + number of neutrons
= atomic number (Z) + number of neutrons
Atomic number (Z) = number of protons
Atomic number and Mass number
A
p+
e-
n
35
17
17
17
A
p+
e-
n
7
3
3
4
Exercise 1A
Use your periodic table to complete the tables below.
A
p+
e-
n
A
p+
e-
n
A
p+
e-
n
Isotopes
Isotopes are atoms
with the same number
of protons but that
have a different
number of neutrons.
We can also say that isotopes are elements with the
same atomic number but different mass numbers.
Isotopes of Carbon
Other Common Isotopes
and its Uses
A
Z
p+
e-
n
A
Z
p+
e-
n
A
Z
p+
e-
n
Examples
A
Z
p+
e-
n
A
Z
p+
e-
n
A
Z
p+
e-
n
An ion is an atom, or group of atoms, that
has a net positive or negative charge.
cation – ion with a positive charge
If a neutral atom loses one or more electrons it
becomes a cation.
Na
11 protons
11 electrons
Na+
11 protons
10 electrons
anion – ion with a negative charge
If a neutral atom gains one or more electrons it
becomes an anion.
Cl
17 protons
17 electrons
Cl-
17 protons
18 electrons
49
How many protons and electrons are
in?
protons
electrons
13
10
How many protons and electrons are
in?
protons
electrons
34
36
27
13
Al
3+
78 234Se
Exercise 1B
Use your periodic table to complete the tables below.
H+
A
Z
p+
e-
n
O-2
A
Z
p+
e-
n
Ca+2
A
Z
p+
e-
n
Mg+2
A
Z
p+
e-
n
Te-2
A
Z
p+
e-
n
Exercise 1
Use your periodic table to complete the table below.
Element
Atomic #
Mass
Protons
Neutrons
Electrons
Symbol
Iodine
53
127
53
74
54
I1-
35
17
1
1
Hydrogen
35
5
Oxygen
Cl10
45
36
B3+
11
16
8
10
Exercise 2
Directions: Fill in the missing information in the
following tables.
A. Neutral Elements
Element
Symbol
Zinc
Cobalt
Tin
(11)
(1)
Co
Sn
(12)
Atomic
Number
(2)
27
50
(13)
Mass
Number
65
(5)
(8)
85
No. of
Protons
30
(6)
(9)
37
No. of
Neutrons
(3)
32
69
(14)
No. of
Electrons
(4)
(7)
(10)
(15)
Atomic
Number
(2)
(6)
35
(13)
Mass
Number
(3)
56
(9)
27
No. of
Protons
(4)
26
(10)
(14)
No. of
Neutrons
7
(7)
45
(15)
No. of
Electrons
10
24
(11)
10
B. Ions
Element
Symbol
Nitrogen
(5)
(8)
Aluminum
(1)
Fe2+
Br(12)