Download Chemical Stability

Chemical Stability
Chemical Stability
• All elements want
chemical stability.
• This can happen by:
1. Forming Ions
2. Forming chemical bonds
(making compounds)
Ion
An atom (or group of atoms) that
has lost or gained e- and has a
net electric charge.
– Cation (+)
– Anion (-)
Atom vs. Ion
http://www.youtube.com/watch?v=dHZlMbBZ0UA
What is an Ion?
https://www.youtube.com/watch?v=900dXBWgx3Y
Valence Electrons
• The number of electrons in the
outer orbital of an atom.
Ionization
Atoms become ions in order to have a
complete energy level.
Fluorine Atom
Fluorine Ion
Ionization
Oxygen atoms have 6 valence electrons
Oxygen ions gain 2 e- and becomes O –2
Ionization
Magnesium atoms have 2 valence electrons
Magnesium ions lose 2 e- and become Mg +2
Oxidation Number
The ion “charge”.
Oxidation Numbers
• Oxygen ion:
O –2
[gained two e-]
• Magnesium ion:
Mg +2
[lost two e-]
Electron Dot Diagrams
Diagrams that display only the
valence electrons
Electron Dot Diagrams
Atom
Ion
Mg
loses 2e-
Mg+2
N
gains 3e-
N
-3
Li
loses 1e-
Li
+1
Polyatomic Ions
A group of atoms with a net charge.
OH -1
NO3 -1
PO4 -3
CO3 -2
Polyatomic Ions
How to Remember Certain Common Polyatomic Ions
Nick the Camel ate a Clam for
Supper in Phoenix
http://www.youtube.com/watch?v=jcKR9U4Ixlk
Compounds
• Two or more
elements chemically
bonded to form a
new substance
(with different properties).
Compounds
• Shown by:
– Chemical Formula H2O
– Structural Formula
O
H
H
Compounds
• Chemical Formula
Coefficient
3H2O
(# of Molecules)
Subscript (# of atoms)
Parentheses (OH)2 = chemical groups
Compounds
• Counting Atoms in Chemical
Formulas
3H2O
Compounds
• Counting Atoms in Chemical
Formulas
6CO2
4NaHCO3
3H3PO4
5Mg(OH)2
2Fe3Al2(SiO4)3
Chemical Bonding
• Chemical Bonding occurs to
achieve Chemical Stability.
• Atoms gain, lose or share
valence electrons.
Why do Atoms Bond?
https://www.youtube.com/watch?v=JOL-nUt_vfo&feature=youtu.be&app=desktop
Bonding Song
http://gaygeek.com.au/blog/2012/09/19/atomic-bonding-love-song-video/
Types of Bonds
• Ionic
• Covalent
• Metallic
The Type of Bonding Depends on the Difference
in the Electronegativity of the Atoms.
Ionic
Non-Polar Covalent
Polar Covalent
Ionic Bonds
• Bonds formed by
the attraction
between oppositely
charged ions.
[e- are given away
or received]
Ionic Bonding
http://www.youtube.com/watch?v=xTx_DWboEVs
Ionic Bonding Rules:
1) Metals form ionic bonds with nonmetals.
2) Metal form ionic bonds with
polyatomic ions.
3) Polyatomic ions form ionic bonds
with each other.
Ionic Bonding
Lewis Dot Diagrams show chemical
bonds resulting from interaction of
valence e- and the ion charges.
_
-
+3
-
Predicting Chemical
Formulas with Oxidation #s
Mg
+2
Ca
+2
+ Cl  MgCl2
-
+ NO3  Ca(NO3)2
-
Writing Formulas for Binary Compounds
http://www.youtube.com/watch?v=vscoYh6m46M
Polyatomic Compounds
http://www.youtube.com/watch?v=3K5V3kxxlI8&feature=related
Naming Ionic Compounds
• Names are additions of cations and
anions
• Cation (1st) is usually the name of
the element.
• Anion (next) is the 1st syllable of
the element PLUS the suffix “ide”
Examples:
Li and F = Lithium Fluoride
Mn and O = Manganese Oxide
Ionic Compounds with
Polyatomic Ions
Name the Cation, then the
Polyatomic Ion.
Ca+2 + (CO3-2 ) ions = Calcium Carbonate
Na+ + (CN- ) ions = Sodium Cyanide
Ba+2 + (SO3-2) ions = Barium Sulfite
Covalent Bonds
• Bonds formed by sharing electrons.
Ionic vs. Covalent Bonding
http://www.youtube.com/watch?v=QqjcCvzWwww
Covalent Bonding
http://www.youtube.com/watch?v=j1e-f1W-0UA
Covalent Bonding Rules:
1) Hydrogen forms covalent bonds with
metals, non-metals and polyatomic ions.
2) Nonmetals form covalent bonds with
other nonmetals.
Covalent Bonds in EDD
Diatomic Molecules
Some atoms, (mainly gases) share
their extra electrons.
Polar and Non-Polar
Covalent Molecules
• If the electronegativity
of the atoms are about
the same, they share
equally and form a
Non-Polar compound.
• If the electronegativity
of one type of atom is
greater than the other,
the electrons are not
shared equally and a
Polar compound is
formed.
Polar and Non-Polar
Covalent Molecules
Naming Covalent
Compounds
• Covalent Compounds are
molecules (not ions) bonded
together.
• Name reflects the numbers of
each element in the compound.
• Use Latin prefixes.
Latin Prefixes
•
•
•
•
•
•
•
One (1): Mono
Two (2): Di
Three (3): Tri
Four (4): Tetra or Tetr
Five (5): Pent or Penta
Six (6): Hex or Hexa
Seven (7): Hept or
Hepta
Examples
P2O5 Di = 2, Pent = 5
Diphosphorous Pentoxide
SiO2 Di = 2 Silicon Dioxide
There’s always an
Exception
• If the first letter of the atom
is a vowel, drop the “a”.
• Examples:
– Dinitrogen Tetroxide
– Carbon Tetrafluoride
Ionic vs. Covalent Molecules
• Ionic compounds form a
network of ions.
• Covalent compounds form
individual molecules.
Ionic vs. Covalent Molecules
Properties of Ionic Compounds
•
•
•
•
High Melting / Boiling Points
Brittle
Many are Water Soluble
When dissolved in
water, conduct
electricity because
they are charged
particles [Electrolytes].
Properties of Ionic Compounds
http://www.youtube.com/watch?v=c546LZPgYwA&safe=active
http://www.youtube.com/watch?v=kgiwdaVMax8&safe=active
How water Dissolves Salt
http://www.youtube.com/watch?v=xdedxfhcpWo
Ionic vs. Covalent Molecules
Properties of Covalent Compounds
•
•
•
•
Low Melting / Boiling Points
Usually Liquid or Gas
“Like Dissolves Like”
Since they are neutral
molecules, they do not
conduct electricity when
dissolved in water.
Properties of Covalent Molecules
http://www.youtube.com/watch?v=OQ-pcxo-Q5c&safe=active
Like Dissolves Like
http://www.youtube.com/watch?v=7OuJ6ierB9s&safe=active