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Basic Chemistry
The Nature of Matter
 Matter refers to anything that takes up
space and has mass.

Matter is composed of elements,
substances that cannot be broken down
into another substance.
There are 92 natural elements.
 Living organisms are made primarily of six
elements.

The Nature of Matter
The Nature of Matter
Elements:
 Made up of tiny particles called
atoms
 Each has its own
 name
 atomic
number
 atomic symbol
Name
Number
Symbol
Hydrogen
1
H
Aluminum
13
Al
Sodium
11
Na
Atomic Structure
Atoms have three main sub atomic
structures:
Name
Charge
Mass
Proton
+
1 amu
Electron
1/1837 amu
Neutron
o
1 amu
Location
inside nucleus
around nucleus
inside nucleus
Atomic Structure
All atoms of the same
element have the same
number of protons
It is also equal to the atomic
number
The Periodic Table

The elements are organized to form the
periodic table.
The columns in the table are groups.
 The rows in the table are periods.


Elements in groups have similar chemical
and physical characteristics.
The Periodic Table
Atomic Structure
The Atomic Mass is the number of
protons and neutrons
Mass
Number of protons:
23
Na
Atomic
Number
11
11
Number of neutrons: 12
(23 – 11)
Number of electrons
11
Composition of Matter- Elements

C
O
H
N
Symbols to know:
Carbon
Oxygen
Hydrogen
Nitrogen
Na Sodium
P Phosphorus
S Sulfur
Cl Chlorine
Mg Magnesium
Fe Iron
Ca Calcium
K Potassium
Composition of Matter- Elements
Isotopes
Many elements have isotopes.
Isotopes have the same atomic number
but a different atomic mass
(they have more or less neutrons)
Composition of Matter- Elements
Isotopes are represented differently, showing
their atomic mass.
Examples:
carbon – 14 is an isotope of carbon with a
mass of 14 (the normal mass is 12)
iodine – 131 is an isotope of iodine with a
mass of 131 (the normal mass is 127)
Composition of Matter- Elements
Certain isotopes are very unstable and
release energy as they “fall apart” or
disintegrate.
These isotopes are called radioactive
isotopes or radioisotopes.
This radiation can be detected with a
Geiger counter.
Uses of Radioactive Isotopes

Radioactive isotopes can be used as
tracers to follow the movement of that
element.

Radioactive isotopes can be used to
sterilize medical and dental instruments.

Radioactive isotopes can also be used to
kill cancer cells.
Uses of Radioactive Isotopes
Atomic Structure

Electrons are found in energy levels outside the
nucleus
The first energy level holds two electrons
 The second energy level holds eight electrons
 The third energy level holds eight electrons
 Other levels can hold more
 Octet Rule: Stable atoms have eight electrons
in their outer level

Atomic Structure
Electrons in the outermost shell are called
valence electrons
 All elements in the same column (group)
of the Periodic table have the same
number of valence electrons
 The valence electrons determine how an
element will react

Arrangements of Electrons in an
Atom
Chemical Bonds

A group of atoms bonded to one another
form a molecule.

If the molecule has more than one type of
element present it is a compound.

Different types of bonds hold molecules
and compounds together.
Chemical Formulas
Types of Formulas
Molecular formulas show the actual
composition of a compound using symbols
of elements and their proportions
Water
H 2O
Examples:
Methane
Carbon dioxide
CH4
CO2
Chemical Formulas
Structural formulas are formulas that show
the bonding of elements in a compound
and their relative positions
Examples:
Water
Methane
Carbon dioxide
H
H
O
H C H
H
O
H
C
O
Composition of Matter - Compounds
Chemical Bonds
A chemical bond is the “glue” that holds the
elements together in compounds.
The valence electrons determine how an
element will react and bond
Types of Chemical Bonds

Charged atoms, or ions, can form when atoms
lose or gain electrons.


Atoms that lose an electron become Positive
Atoms that gain electrons become Negative

Positive and negative ions are attracted to one
another and bond together in ionic bonds.

Usually between a metal and non metal that are
far apart horizontally on the periodic table.

A salt is a dry solid composed of atoms
connected by ionic bonds.
Types of Chemical Bonds
Ionic Bonds
Sodium (one valence electron)
Loses the electron
Becomes positive (+)
Chlorine (seven valence electrons)
Gains the electron
Becomes negative (-)
Opposites Attract!
Each outer shell has eight electrons
Types of Bonds
Covalent bonds
 formed when electrons are shared among
elements in a compound.
 usually formed between two non metals or
a non metal and hydrogen
 Models or diagrams can be drawn to show
the shared electrons
Types of Chemical Bonds
Chemical Equations
Equations show the:
 chemicals that are reacting
 products that are made
 amount of each chemical involved
In equations, reactants are on the left
the products are on the right.
Example:
Water produces hydrogen and oxygen
2H2O
2H2 + O2
Chemical Reactions
The chemical reaction for photosynthesis
6 CO2 + 6 H2O  C6H12O6 + 6 O2
carbon
dioxide
water
glucose
oxygen

Molecules that participate in a reaction are
reactants.

Molecules formed by a reaction are products.
Water, Acids, Bases and pH
Dissociation occurs when an ionic
compound separates into its
ions.
Example:
Salt (NaCl) breaks apart into Na+
and ClNa+
Cl-
Acids and Bases

When water dissociates, it releases an
equal number of ions.
Hydrogen ions (H+)
 Hydroxide ions (OH-)

H–O–H
H+ + OH-
Water, Acids, Bases and pH
Acids
Acids will dissociate in
water to release a
hydrogen ion (H+)
Examples:
HCl
H2SO4
HC3H5O3
(Notice the H at the front of the
formula)
Water, Acids, Bases and pH
Bases will dissociate
in water and release
OH- (hydroxyl) ions
They have a low
concentration of H+
Examples:
NaOH
KOH
(notice they end in –OH)
pH and the pH scale
The pH is a mathematical way of
indicating the number of H+ ions in a
solution.
 The lower the number, the higher the
concentration.


The pH scale is used to express acidity or
basicity (alkalinity).
Water, Acids, Bases and pH
Acids have a low pH (less than 7) and bases
have a high pH (more than 7)
1
7
14
Strong
Acid
Neutral
Strong
Base
The farther away from neutral, the stronger
the acid or base.
Water, Acids, Bases and pH










Extremely acidic:
Very strongly acid:
Strongly acid:
Moderately acid:
Slightly acid:
Neutral:
Slightly alkaline:
Moderately alkaline:
Strongly alkaline:
Very strongly alkaline:
lemon=2.5; vinegar=3.0; stomach acid=2.0
tomatoes=4.5
carrots=5.0; asparagus=5.5; cabbage=5.3
potatoes=5.6
salmon=6.2; cow's milk=6.5
saliva=6.6–7.3; blood=7.3; shrimp=7.0
eggs=7.6–7.8
sea water=8.2; sodium bicarbonate=8.4
borax=9.0
milk of magnesia=10.5, ammonia=11.1;
Water, Acids, Bases and pH
Mixing an acid with a base a chemical
reaction will change the pH of the mixture
 Hydrogen ions will react with the hydroxyl
ions and form water
H + + OHHOH
 If the ions are in equal amounts, the
mixture becomes neutral (pH 7)
 This is called a neutralization reaction.
 The remaining ions form a salt.

Buffers and pH

Within the body, the pH is kept in a narrow
range to maintain health.

A buffer is a chemical or combination of
chemicals that keeps a pH within a given
range.

Buffers resist changes in pH by taking up
+
extra H or OH from solution.
Buffers and pH