TEK 8.5
Matter and energy.
The student knows that matter
is composed of atoms and has
chemical and physical
properties.
The student is expected to:
A) Describe the structure of atoms,
including the masses, electrical
charges, and locations, of protons and
neutrons in the nucleus and electrons
in the electron cloud.
B) Identify that protons determine an
element’s identity and valence
electrons determine its chemical
properties including reactivity.
C) Interpret the arrangement of the
Periodic Table, including groups and
periods, to explain how properties
are used to classify elements.
D) Recognize that chemical formulas
are used to identify substances and
determine the number of atoms of
each element in chemical formulas
containing subscripts.
E) Investigate how evidence of chemical
reactions indicate that new
substances with different properties
are formed.
F) Recognize whether a chemical
equation containing coefficients is
balanced or not and how that relates
to the law of conservation of mass.
Vocabulary
Atom
Element
Subatomic
particle
Neutron
Proton
Electron
Atomic Theory
John Dalton
JJ Thomson
Ernest
Rutherford
Neils Bohr
Erwin
Schrodinger
Louis de Broglie
Atomic Structure
Notes
Element
-substances that are the
building blocks of all matter
-made up of one kind of atom
-Ex. Carbon, Hydrogen, Oxygen
Atom
-The smallest particle into
which an element can be
divided and still maintain the
properties of the element.
-made up of sub-atomic
particles
Subatomic Particles
3 main structures
1. Protons
2. Neutrons
3. Electrons
Protons (+)
• particles found in the nucleus
of an atom.
• have a positive charge
Neutrons
• Particles found in the nucleus
of an atom.
• Have a neutral charge
Electrons
(e )
• Particles found in the
electron cloud (orbiting the
nucleus)
• Negatively charged
AMUs
-atomic mass unit aka Dalton
-used to describe the mass of
subatomic particles
-equal to 1.660538921×10−27 kg
Sizes of Subatomic
Particles
Protons
Neutrons
Electrons
.0005 AMU
1 AMU
1 AMU
Modeling Parts of an Atom
parts of an atom.
Electron
Cloud
Nucleus
Nucleus
makes up
99.99%
of atomic
mass
Atomic Theory
-a scientific theory of the
nature of matter, which states
that matter is composed of
discrete units called atoms.
Democritus
-influential
pre-Socratic
philosopher
-formulated
an atomic
theory
-400 B.C.
John Dalton
1803
Solid Ball +
JJ Thomson
1897
Plum pudding
Plum Pudding Model
Aka
Muffin Model
Aka
Arroz con Leche Model
Discovered Electrons
Ernest Rutherford
1909
Planetary Model
Discovered Protons
Neils Bohr
Electron
1913
Proton
Neutron
Nucleus
Louis de Broglie
& Erwin Schrodinger
Electron Cloud Model
1926
1927 Solvay Conference
Atoms Part II
PERIODIC TABLE
Vocabulary
Atomic Number
Atomic Mass
Atomic Symbol
Valence electron
Orbital
Electron Shell
Energy Level
Valence shell
Atomic Number
-reflects the # of protons in the
nucleus and electrons in the
electron cloud of a balanced
atom of that element.
ATOMIC NUMBER = # OF PROTONS
& ELECTRONS
Atomic Number
Atomic Mass
-the sum of the protons and the
average number of neutrons
Atomic Mass
# of Neutrons
Atomic Mass (rounded to
nearest whole number)
minus # of protons
AM -
+
p
=N
AM-P=N Example
Atomic Symbol
Putting it all together
Atomic
Number
Element
Symbol
Atomic
Mass
Electron Orbitals
aka
Electron Shells
aka
Energy Levels
-the amount of energy carried by
an electron in an atom
-determines the electron’s
average distance from the
nucleus
Energy Levels
8 e-
8 e-
Nucleus
2 e-
Nucleus
Valence Shell
-the outermost shell of an atom in
its uncombined state
-all atoms want their valence
shells filled.
Valence Electron
• electrons located in the
valence shell
• # of valence e- will determine
the reactivity of the atom.
• The more Valence e’s the
more stable and HAPPY (Nole
Gases)
• The less valence e’s the more
reactive and EXPLOSIVE or
UNHAPPY (Alkali Earth
Metals)