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Transcript
Atomic Structure
3.1
October 1, 2015
 Objective: Explain Dalton’s atomic theory and
describe why it was more successful than
Democritus’ atomic theory.
Do Now: Name the 3
subatomic particles found in
an atom (the 3 parts of an
atom).
Atomic History
•In 400 BC a Greek
Philosopher, Democritus
suggested the universe
was made of invisible
units--atoms.
1800’s John Dalton’s Theory
(Still Accepted)
1. Every element is made of
tiny, unique particles called
atoms
2. Atoms of different elements
can join to form molecules.
John Dalton’s Theory- Disproved
3. Atoms are the smallest
particles and cannot be
subdivided.
4. Atoms of the same
element are exactly alike
in mass
JJ Thomson
Credited with
discovering negative
charged particles
called electrons.
https://www.youtube.com/watch?v
=2xKZRpAsWL8
https://www.youtube.com/
watch?v=O9Goyscbazk
Rutherford
Credited with
discovering nucleus.
and atoms are mostly
empty space.
https://www.youtube.com/watch?v=
5pZj0u_XMbc
http://micro.magnet.fsu.edu/electromag/java/rutherford/
Further Research Finding
Later on, the discovery of protons and
neutrons were discovered in the nucleus.
And it was later concluded that all atoms
are neutral in charge.
The number of protons and electrons in
any atom are always equal.
Niels Bohr
Suggested that electrons
move around atoms in set
paths around the nucleus.
He said each path is an
energy level
See visual aid in Ch4 online txtbk
Today’s Theory
It is impossible to pinpoint an
electron’s exact position due
to its tremendous speed.
Electrons do not move around
in definite paths.
Today’s Theory
Electrons are found in
orbitals within energy levels.
(s, p, d, and f )
a region in an atom where
there is a high probability of
finding electrons.
Today’s Theory
Electrons are now
viewed as waves
vibrating on a string
rather than simple
particles.
Wave-Particle Duality
Theory
What are atoms?
The smallest part of
an element that still
has the element’s
properties.
Parts of an atom
Nucleus
Proton
Neutron
Electron
Subatomic particles
Nucleus
•center of an atom
•positively charged
•makes up 99.9% of the atom’s
mass
•contains protons and neutrons
Protons
Charge (+)
Mass is equal to 1 atomic mass
unit (amu)
Found in the nucleus
Identifies the element/atom
Neutrons
Charge (0) – neutral
Mass is equal to 1amu
Found in the nucleus
Helps determine mass
Electrons
•Charge is negative (-)
•Mass is equal to 0 amu
•Found outside the nucleus, in
the electron cloud
Energy levels
1st level holds up to 2 e2nd level holds up to 8 e3rd level holds up to 8 or 18 e4th level holds up to 8, 18, or 32 eOuter Level holds up to 8 e(called valence electrons)
Valence Electron
The number of electrons
in the outermost electron
shell.
Most important
Oct 6, 2014
 Objective: Quantify atoms and ions based on subatomic particles
 Do Now: How many valence e- will the following
elements have? (Draw out your energy orbitals with
the “nucleus” in the center to show work)
 Carbon
 Na
 Hydrogen
 Chlorine
A Guided Tour of the
Periodic Table
3.2
https://www.google.com/webhp?sourceid=chromeinstant&ion=1&espv=2&ie=UTF8#q=meet%20the%20elements Meet the Elements
Periodic Law
•Properties of elements tend to
change in a regular pattern
when elements are arranged in
order of increasing atomic
number.
Periodic Law
Periodic Table is set up
by increasing atomic
number.
Atomic Number is the #
of protons in the atom.
Average
Atomic
Mass
Atomic Number
•tells you number of protons
•Never Changes for an atom.
•Appears as a whole # on the periodic
table.
•No two elements can have same
atomic #.
Atomic Number
Atomic
Number
# of
protons
Mass Number
The mass of an atom
Total number of protons plus
neutrons in the nucleus of a single
atom.
Atoms of the same element won’t
always have the same mass number
Mass Number
# of
protons
# of
neutrons
Mass
#
Isotopes
•Any atoms having the same
number of protons but
different number of neutrons.
•So they also have different
mass numbers.
Average Atomic Mass
Average mass of all known
isotopes for an element
Found on the periodic table
as a number with a decimal
Atom’s Charge
•They are neutral.
•All atoms have the same number
of protons and electrons.
•Charges cancel each other out.
Ions
Charged particles.
Form when atoms lose or gain
electrons.
They do this so the ions have a
full outer shell
Two Types.
Cations
•Positively charged ions.
•Form when atoms lose electrons.
•Metals
•Left side of table
Cations
# of protons greater
than # of electrons
More (+) than (-)
Na Atom
+
Na
Cation
Anions
•Negatively charged ions.
•Form when atoms gain
electrons.
•Nonmetals
•Right side of table
Anions
# of protons less
than # of electrons
More (-) than (+)
Cl
Cl atom
Anion
Quantifying atoms or ions
+1
Protons = 3
Neutrons = 7-3 = 4
Electrons = 3
Electrons = 3 -1 = 2
Families of Elements
3.3
Periodic Table
Periods
-a horizontal row of
elements.
-Tells you the electrons
energy level.
Periodic Table
Groups (families)
-a vertical column of
elements.
-Tells us the # of valence
electrons and the
elements’ chemical
properties.
Types of Elements
1. Metals
2. Nonmetals
3. Semiconductors/metalloid
Transition Metals
Inner Transition Metals
Alkali Metals Group 1
Most reactive metals
one valence eFound as compounds (salts) and not
elements due to reactivity.
As elements they are soft metals and
good conductors.
fun
Alkaline-earth Metals
Group 2
Less reactive than Alkali
They are also more commonly
found as compounds
2 most common are Ca and
Mg.
Transition Metals Groups 3-12
Less reactive than groups 1
and 2
Good conductors
Transition Metals
All solids with the
exception of mercury
Valuable metals
(Ag, Au, Pt, Cu, Ni, Fe,
Co)
Non Metals
Are not able to conduct
electricity or heat very well.
Found in groups 13-18, with
the exception of hydrogen
Carbon
Found as an element (coal, diamond,
graphite)
Found in millions of different compounds
Called Organic Compounds
HYDROGEN
It is a gas/nonmetal
A very explosive gas.
It is located in group one
because it has one valence
electron
 http://www.youtube.com/watch?v=KLzY88uHFn0
Oxygen and Nitrogen
Oxygen is the most common
element found on Earth
Nitrogen most common gas
found in the atmosphere
Halogens Group 17
Most reactive nonmetals
Form salts with group 1
Used to kill bacteria
Bromine only liquid
nonmetal
Noble Gases Group 18
Stable and not reactive.
(inert)
Don’t form compounds.
They have a full valence shell.
Metalloids
(Semiconductors)
7 elements on the step
Properties of both metals and nonmetals.
Silicon the most familiar
(computer chips)
Inner Transition Metals
Two rows at the bottom
Some are Radioactive ex.
Uranium
93 and greater are all
manmade