Chemical Stability

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