Transcript Ch. 3

Atomic Structure
every atom has two main parts:
1) nucleus- the center of the atom and is
made up off protons (+) and neutrons (0).
2) electron cloud- surrounds the nucleus and
is made up of electrons (-)
Electron Cloud
the electron cloud is organized into
energy levels
1st energy level = 2 electrons
2nd energy level = 8 electrons
valence electrons – the electrons in the
outermost energy level.
electron
cloud
1st energy
level
HYDROGEN
available space
for another
electron
0
nucleus
atomic number – number of protons in the nucleus.
balanced atom – equal number of protons and electrons; has no
charge.
CARBON
2nd energy
level
00
000
0
balanced atom
6 proton = 6 electrons
1st energy
level
LITHIUM
3+
balanced atom
3 proton = 3 electrons
FLUORINE
9+
balanced atom
9 proton = 9 electrons
Meaning of Life
balanced atoms = unhappy atoms
stable atoms = happy atoms
Atoms become stable when they complete
their outermost energy level.
2 ways to complete the outmost energy level:
1) find a home for their valence electrons
2) get electrons from other atoms.
LITHIUM
Li
FLUORINE
Fl
1 Lithium & 1 Fluorine = Lithium fluoride
structure
formula
Li
F
LiF
Carbon & Hydrogen
H
C
H
H
H
1 Carbon & 4 Hydrogen = Methane
H
structure
H
C
H
formula
CH4
H
Oxidation Numbers
The oxidations number indicates if an atom is
going to give up electrons or take in electrons
in order to become stable.
Positive oxidation numbers mean the atom is
going to give up electrons.
Negative oxidation numbers mean the atom is
going to take in electrons
LITHIUM
Li
3+
balanced but not
stable
+1
Stable
and happy
FLUORINE
9+
balanced but not
stable
F -1
Stable
and happy
H
H
C
H
C
-4
CH4
H
H +1
Element
Atomic #
Valance e-s
Oxidation #
N
7
5
-3
O
8
6
-2
K
19
1
+1
Al
13
3
+3
C
6
4
+/-4
10
8
0
Ne
ion – an atom or group of atoms that has
an electric charge.
Li+
O-2
Mg+2
F-
polyatomic ions- a group of atoms that
react as a single ion.
NH4+
NO3-
SO4-2
PO4-3
ammonium
nitrate
sulfate
phosphate
Polyatomic Ions
Acetate
Hydrogen Carbonate
Hydroxide
Ammonium
NH4 +1
C2H3O2 -1
HCO3 -1
OH -1
Nitrate
NO3 -1
Nitrite
NO2 -1
Chlorate
ClO3 -1
Carbonate
CO3 -2
Sulfate
SO4 -2
Sulfite
SO3 -2
Phosphate
PO4 -3
Chemical Formulas
Chemical formulas have positive and
negative ions when combined have their
oxidation numbers equaling zero.
+
Mg+2 + Cl-1
K+ + SO4-2
NH4+ + S-2
Zn+2 + PO4-3
Ca+2
O-2
CaO
calcium oxide
MgCl2
magnesium chloride
K2SO4
potassium sulfate
(NH4)2S ammonium sulfide
Zn3(PO4)2 zinc phosphate
Atoms become stable when they react
with other atoms.
When atoms react, they form a chemical
bond.
3 Types of Chemical Bonds:
1) Ionic
2) Covalent
3) Metallic
Ionic bonds form as a result of the attraction
between positive and negative ions.
+
Na
Cl
NaCl
sodium chloride
table salt
-
Covalent bonds form when electrons are
shared between atoms.
O
+
O
O
O
O2
being happy some of the time is better
than none of the time.
Metallic bonds form between positively
charged metal ions and the free moving
valence electrons.
-
+
-
+
-
-
+
-
+
-
-
+
-
+
-
-
-
+
-
-
-
-
+
-
+
-
+
-
-
+
-
+
-
+
-
-
A “sea” of electrons moving around
the positively charged metal ions
+
-