Chemical Stability• All elements want chemical stability.• This can happen by:
1. Forming Ions2. Forming chemical bonds
(making compounds)
IonAn atom (or group of atoms) that has lost or gained e- and has a net electric charge.
– Cation (+)– Anion (-)
Atom vs. Ionhttp://www.youtube.com/watch?v=dHZlMbBZ0UAWhat is an Ion?https://www.youtube.com/watch?v=900dXBWgx3Y
Valence Electrons• The number of electrons in the
outer orbital of an atom.
IonizationAtoms become ions in order to have a complete energy level.
Fluorine Atom Fluorine Ion
IonizationOxygen atoms have 6 valence electronsOxygen ions gain 2 e- and becomes O –2
IonizationMagnesium atoms have 2 valence electronsMagnesium ions lose 2 e- and become Mg +2
Oxidation NumberOxidation NumberThe ion “charge”.The ion “charge”.
Oxidation Numbers• Oxygen ion:
O –2
[gained two e-]
• Magnesium ion: Mg +2
[lost two e-]
Electron Dot DiagramsDiagrams that display only the valence electrons
Electron Dot DiagramsAtom Ion
Mgloses 2e- Mg+2
N gains 3e- N -3
Liloses 1e- Li +1
Polyatomic IonsA group of atoms with a net charge.
OH -1
NO3 -1
PO4 -3
CO3 -2
Polyatomic IonsHow 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
OH 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 BondingChemical Bonding• Chemical Bonding occurs to Chemical Bonding occurs to
achieve Chemical Stability.achieve Chemical Stability.• Atoms gain, lose or share Atoms gain, lose or share
valence electrons.valence electrons.Why do Atoms Bond?Why do Atoms Bond?https://www.youtube.com/watch?v=JOL-nUt_vfo&feature=youtu.be&app=desktop
Bonding SongBonding Songhttp://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 Bondinghttp://www.youtube.com/watch?v=xTx_DWboEVs
Ionic Bonding Rules:1) Metals form ionic bonds with non-
metals.2) Metal form ionic bonds with
polyatomic ions.3) Polyatomic ions form ionic bonds
with each other.
Ionic BondingLewis Dot Diagrams show chemical bonds resulting from interaction of valence e- and the ion charges.
_
- +3 -
Predicting Chemical Formulas with Oxidation #s
Mg +2 + Cl - MgCl2
Ca+2 + NO3- Ca(NO3)2
Writing Formulas for Binary Compounds
http://www.youtube.com/watch?v=vscoYh6m46M
Polyatomic Compoundshttp://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 FluorideMn and O = Manganese Oxide
Ionic Compounds withPolyatomic Ions
Name the Cation, then the Polyatomic Ion.
Ca+2 + (CO3-2
) ions = Calcium CarbonateNa+ + (CN- ) ions = Sodium CyanideBa+2 + (SO3
-2) ions = Barium Sulfite
Covalent Bonds• Bonds formed by sharing electrons.
Ionic vs. Covalent Bondinghttp://www.youtube.com/watch?v=QqjcCvzWwww
Covalent Bondinghttp://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 MoleculesSome 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
ExamplesP2O5 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 MoleculesProperties of Ionic Compounds• High Melting / Boiling Points• Brittle• Many are Water Soluble• When dissolved in
water, conductelectricity becausethey are chargedparticles [Electrolytes].
Properties of Ionic Compoundshttp://www.youtube.com/watch?v=c546LZPgYwA&safe=activehttp://www.youtube.com/watch?v=kgiwdaVMax8&safe=active
How water Dissolves Salthttp://www.youtube.com/watch?v=xdedxfhcpWo
Ionic vs. Covalent MoleculesProperties of Covalent Compounds• Low Melting / Boiling Points• Usually Liquid or Gas• “Like Dissolves Like”• Since they are neutral
molecules, they do notconduct electricity whendissolved in water.
Properties of Covalent Moleculeshttp://www.youtube.com/watch?v=OQ-pcxo-Q5c&safe=active
Like Dissolves Likehttp://www.youtube.com/watch?v=7OuJ6ierB9s&safe=active
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