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Matter: all matter is made up of
atoms.
is anything that has a
mass and a volume
all matter has a specific
density or arrangement
of atoms that can be used
to identify it.
John Dalton
(aka Jack)
1. Atoms are the smallest form of
matter
2. Atoms make up all matter
3. Atoms of the same element are
the same
4. Atoms cannot be broken down
5. Atoms combine in specific ratios
Thomson:
Discovered the electron
First model of atom
Rutherford:
Discovered presence of nucleus
And protons
Atom was mostly empty space
Chadwick:
Discovers the neutron
Bohr:
Suggested electrons move in energy
Levels
Presents model used today
(although not completely accurate)
M shell
L shell
+
n
K shell
nucleus
Electron cloud model
Electron cloud
Nucleus
Neutron
Proton
PERIODIC TABLE
Elements: roughly 88 naturally occurring
roughly 20 man made
organized arrangement
metals, nonmetals, metalloids,
noble gasses
pure substance
Protons
•Positively charged
•Found in the nucleus
•Identifies element
•Gives the element its atomic number
•Gives nucleus its positive charge
•Contributes to the atom’s reactivity
• +
Protons
•Positively charged
•Found in the nucleus
•Identifies element
•Gives the element its atomic number
•Gives nucleus its positive charge
•Contributes to the atom’s reactivity
• +
ELECTRONS
oNegatively charged
oFound on the energy shells
oDetermines the reactivity of the atom
oHas very small mass-not normally considered
when calculating mass of atom.
o e
ATOMIC MASS: no. protons + neutron
-- ATOMIC NUMBER: no. protons
_________________________________
no. neutrons
At. Mass 7
-- At. # 3
4
___________________________
Protons:
Neutrons:
Electrons:
3
4
3*
Li
*all unbonded atoms are electrically
and chemically neutral.
# of + = # of e.
Isotopes: Atoms of the same element that
Differ from each other by the number of
Neutrons.
Isotopes have the same Atomic number but
A different Atomic Mass.
45 known isotopes of iodine
I 127, 53
I 136, 53
15 known isotopes of carbon
C 12, 6
C 14, 6
Element – pure
Compound – 2 or more elements
chemically combined
homogeneous
Mixture – 2 or more elements,
compounds, or both physically
combined.
homogenous or heterogeneous
Element – pure
Compound – 2 or more elements
chemically combined
homogeneous
Mixture – 2 or more elements,
compounds, or both physically
combined.
homogenous or heterogeneous
Liquids:
indefinite shape
definite volume
MA faster than solid
*MD larger than solid
Gas: Indefinite shape
Indefinite volume
MA fast
Ma weak
MD large
MA, MD increased by increases in
Temperature = increases in energy.
Increases in MA and MD = changes
in state.
State changes are a result of increases* in thermal
energy which directly increases* MD and MA.
MA
condensation
MD
Decrease
KE dec
freezing
vaporization
melting
MA
MD
Increase
KE inc
•
Bohr model
Lithium
Atomic mass = 7
Atomic number = 3
+
=
3
n =
4
e =
3
+
3
n
4
Electron configuration:
2-1
The outer most shell is called
the valence shell and is often unstable, meaning
It does not contain the octet number of electrons
In order for the atom to become stable or
Fill the shell to the octet rule, this shell will be
The one to bond.
Li
F
Atoms that are not stable cause trouble –
they can be flammable, explosive, toxic.
These problems are what make an atom
reactive – meaning they want to become
stable.
Bonding:
Ionic loss or gain of electrons
Covalent sharing of electrons
IONIC BONDING: OCCURS BETWEENMETALS: LESS THAN 4 VALENCE ELECTRONS
AND
NONMETALS: MORE THAN 4 VALENCE ELECTRONS
***REMEMBER: ATOMS WANT TO USE LITTLE E!!
METALS WILL LOSE ELECTRONS
NONMETALS WILL GAIN THOSE ELECTRONS LOST
Ionic Bonding:
occurs between metal and nonmetal
> 4 val. e
< 4 val. E
lose e
gain e
form ions – charged atoms because
the # of protons does NOT
equal # electrons.
+ ion
- ion
Na: metal, > 4 val. e, lose e
+
F: nonmetal, < 4 val. e, gain e
NaF sodium flouride
+
+
Li2O
Bonding between atoms is a result of:
a. atoms need to be stable
b. atoms need to exist in a lower
energy state
c. attraction of positive nucleus and
negative electrons
d. size of the atom’s radius
COVALENT BONDING
SHARING OF ELECTRONS
ATOMS REMAIN NEUTRAL
OCCURS BETWEEN:
2 NONMETALS
A NONMETAL AND A METALLOID
HYDROGEN AND ALL NONMETALS
PRODUCES WEAK BONDS
PRODUCES COMPOUNDS THAT HAVE LOW
MELTING POINTS
ALL ORGANIC COMPOUNDS ARE COVALENT
COVALENT BONDS
Between hydrogen and
A nonmetal
Fluorine has 7 valence electrons
It needs 8 in order to exist in a lower
Energy state. It could bond ionically
With A metal or covalently with hydrogen
by sharing one of its valence electrons.
Hydrogen has only one
Electron and therefore will never
Lose that electron. In order for
It to become stable and exist
In a lower energy state, it will
Share its only electron with
fluorine
COVALENT BONDINGBETWEEN
2 NONMETALS
Nonmetals, because they have more than 4 valence electrons and
especially those that have small atomic radii, will bond with themselves in order to become stable and exist at a lower energy state.
These atoms will be called DIATOMS. There are 7 diatoms
That you will need to memorize. They are F, Cl, Br, I, O, N, H.
COVALENT BONDING
BETWEEN
NONMETAL AND A METALLOID
Carbon will be our only metalloid with 4 valence electrons
Fluorine is a
Nonmetal with 7
Valence electrons
The resulting stable cmpd
Contains 4 F and 1 C.
Because the atoms never
LOST E’s they remain
neutral.
Comparison of bonds
• Ionic Bonding:
• occurs between metal
and nonmetal
• lose e
gain e
• form ions – charged
atoms
• COVALENT BONDING
 SHARING OF ELECTRONS
 ATOMS REMAIN
NEUTRAL
 OCCURS BETWEEN:
 2 NONMETALS
 A NONMETAL AND A
METALLOID
 HYDROGEN AND ALL
NONMETALS
POLARITY
UNEVEN DISTRIBUTION OF CHARGES
__
+
On polar molecules, electrons are controlled by one
Of the atoms.
Chemical and physical comparison
Physical properties
• Properties that describe the
physical appearance of
matter, such as size, shape,
texture, density.
• Properties can change and
be returned to original
properties.
• Properties may be size
dependent or size
independent.
Chemical properties
• Properties describe the
chemical composition of the
matter, such as the
elements that are bonded
and the specific ratio; H2O,
Fe2O3.
• Chemical properties do not
change without changing
the composition of matter.
• Properties are not affected
by size.
Chemical and Physical changes
Physical Changes
• The changes affect the way
the matter appears; size,
color, shape.
• These changes can be
reversed.
• The properties of the new
matter are the same as the
original.
Chemical Changes
• The changes affect the
appearance of matter.
• The changes change the
chemical composition of the
matter.
• These changes cannot be
reversed.
• The properties of the new
matter are different than
the original.