I. Electronegativity and Bonding
 Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons .
 No electronegativity difference (0) between two atoms leads to a pure non-polar covalent bond.
 A small electronegativity difference (0-2.0) leads to a polar covalent bond.
 A large electronegativity difference leads to (2.0 or more) an ionic bond.

I. Electronegativity and Bonding
Which type of bond will be formed by Au and O?___________
Which type of bond will be formed by F and Cl? ____________

II. Intramolecular
Intramolecular bonds:
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Intramolecular bonds are those within a molecule or compound.
These bonds are relatively strong
Methane
Intramolecular bond

II. Intramolecular (Within a molecule
– strong forces)
Intramolecular bond

Ionic Bonds
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Between metal (cation) and nonmetal (anion) that transfer valence electrons in order to gain octets/be more stable
Attraction between positive and negative ions results in the formation of crystalline structures with high melting points
Picture:

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Ionic solids break apart into positive and negative ions when in solution (known as electrolytes) these solutions conduct electricity

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Many batteries contain two metals with different electronegativities and some sort of electrolyte solution.

(This simple voltaic cell contains an acid as the electrolyte)

Picture:
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Between 2 or more nonmetals that share valence electrons to gain an octet
Sharing of electrons results in the formation of molecular compounds with low melting points
Molecules do not break apart in solution, so do not conduct electricity (nonelectrolytes)


Can be polar 
uneven sharing of electrons leads to partial charges

Or, nonpolar  even
sharing of electrons leads to no partial charges
Water: A polar covalent molecule

Polar (partially charged)
Nonpolar (no charges)


“Like dissolves like” – Polar substances will only dissolve in polar
substances. Water is polar.
Oil is nonpolar. They do not dissolve in one another!

By the way,
 Sometimes nonmetals form network solids
 For example, carbon atoms can arrange themselves into solids such as diamonds or graphite


Ionic and covalent bonding

Which solution contains a salt (ionic compound)?
Which solution contains a nonpolar covalent compound?

Picture:
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Between metal ions (cations) that have loosely-held electrons called a
“sea of electrons”
Freely-flowing electrons create metallic solids that are malleable and conductive

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Metallic bonding

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Most metals used in daily life are alloys
- combinations of elements that contain one or more metal

III. Intermolecular Bonds
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Intermolecular forces are between separate molecules
These bonds are relatively weak

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Between polar covalent molecules or any molecule with a permanent dipole (partial charge)
Partial positive charges are attracted to partial negative charges - creates weak bond between molecules
Picture:

Hydrogen Bonds (a type of dipole-dipole bond)
Hydrogen Bond:

A hydrogen bond is a special dipole-dipole interaction between molecules with a hydrogen atom bonded to another atom with a relatively high electronegativity like O,
N, or F

Hydrogen has a lower electronegativity, so it is partially positive (  +)

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Partially positive hydrogens are attracted to partially negative ends of other molecules – creates weak bond between water molecules that makes water “sticky”

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Occurs due to random movement of electrons and occasional “pile-ups” of electrons on one side of atom
Temporary dipoles
(charged areas) can be created very briefly and cause atoms to be very weakly attracted to each other
Picture:

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London dispersion forces

Geckos use London dispersion forces to climb up surfaces

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Dispersion forces are greater for larger atoms
Why?____________________________
________________________________

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Use 20-25 words to summarize the main points from these notes.

Partner 2 tell partner 1 your gist
Partner 1 repeat what your partner said back to them
Both partners praise each other after talking
(Good job. Thank you.)