Atomic Theory
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Transcript Atomic Theory
ATOMIC THEORY
IN THE BEGINNING
Atoms originally named by _____________
Believed the a substance could be divided over
and over again only to a point
If divided further it would not be that substance
anymore
His atoms were solid, homogeneous spheres
LAW OF CONSERVATION OF MASS
LAW OF DEFINITE PROPORTIONS
LAW OF MULTIPLE PROPORTIONS
JOHN DALTON
Proposed atomic theory in 1803
Parts of Theory
His atom is also a solid, homogeneous sphere
CATHODE RAYS
J.J. THOMSON’S MODEL
RUTHERFORD’S GOLD FOIL EXPERIMENT
RUTHERFORD’S MODEL
NIELS BOHR’S MODEL
COMPARING THE PARTICLES
In the nucleus
Protons
Charge= ________
Mass = ___________________
Neutrons
Charge= ______
Mass= ______________________
Surrounding the nucleus
Electron
Charge= ______
Mass= _______________________
ELEMENTS
Composed of only one type of _________
Identity is based on ___________ number
Atomic number (___)- number of protons found
in that atom (ID number for elements)
Elements are ordered in periodic table according to
this number
Mass Number (___)- mass of atom in atomic unit
Really the mass of the __________________________
Electrons are so tiny that they don’t count
CALCULATING PNE (GROUND STATE)
# of protons= __________________
# of electrons= _________________
# of neutrons= _______________________________
ISOTOPES
Different forms of the same atom type
Differ by number of ____________ (so therefore
differ by mass as well)
Isotope names- element name – mass number
Lithium-6
Lithium-7
Lithium-8
IONS
Atoms that lose or gain ___________ form ions
Ions have a charge
Cation- ion with a ____________ charge
Anion- ion with a _____________ charge
CATION
Forms when atoms _________ electrons
ANION
Forms when atoms __________ electrons
NAMING IONS
Cations
With one common charge
“Name of the element” ion
For example, Ca+2 is calcium ion
Multivalent
“Name of element” (charge in Roman numerals) ion
+2 is iron (II) ion
For example, Fe
Anions
“Name of the element with ending changed to –ide”
ion
For example Cl is chloride ion
CALCULATING PNE (IONS)
# of protons= atomic number
# of electrons =
atomic number – charge for cations
Atomic number + charge for anions
# of neutrons= mass number – atomic number
ATOMIC MASSES ON THE PERIODIC TABLE
Atomic masses on periodic table are an average
of all naturally occurring ___________ based on
their abundance
Calculating Atomic Mass
Need
Mass of each isotope
Fractional abundance of each isotope (must change to
fraction if given as %)
For each isotope
Multiple the mass and the fractional abundance
Add all of the answers together to get the atomic
mass
DMITRI MENDELEEV
Proposed period table (1869)
Arranged elements according
to ________________
Grouped elements by similar
properties
Left holes for undiscovered
elements and predicted their
properties
GERMANIUM PREDICTION
STRUCTURE OF MODERN PERIODIC
TABLE
Elements are arranged by
_____________________
Elements occur in rows (or
_________)- 7 periods in all
Elements occur in columns (or
___________________) with similar
chemical properties- 18 in all
______________ law- elements can
be organized into patterns in the
table based on chemical and
physical properties
PERIODIC GROUPS
OTHER PERIODIC GROUPINGS
WHERE DO THEY BELONG?
The two series actually belong in the table like
this, but we put them at the bottom to save space
METALS, NONMETALS, AND
METALLOIDS
Metal
Good conductor of electricity
Malleable
Ductile
Shiny
Nonmetal
Poor conductor of heat and
electricity
Often gas or dull, brittle
solid
Metalloid
Properties in between the
other two
NATURAL STATES OF ELEMENTS
Most occur as
solids
Br and Hg can
occur as a liquid
Other occur as gas
NATURAL STATES OF ELEMENTS
(CONT)
Many elements can exist in different forms
naturally
Carbon
Both graphite and diamond are carbon, the atoms
are just arranged differently
DIATOMIC ELEMENTS
Element occurs naturally in pairs
7 elements
Hydrogen (H2)
Nitrogen (N2)
Oxygen (O2)
Fluorine (F2)
Chlorine (Cl2)
Bromine (Br2)
Iodine (I2)