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Chemical Bonding

A mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together.

Atoms combine to minimize potential energy, which makes them more stable.

It is in the breaking and forming of chemical bonds that the vast majority of Chemistry takes place.

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Types of Chemical Bonds

Metallic Bonds Metal bonded with metal Valence electrons are shared in an electron sea

Ionic Bonds Metal bonded with nonmetal Valence electrons are transferred from positive

ions to negative ions Covalent Bonds

Nonmetal bonded with a nonmetal Valence electrons are shared in electron pairs

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Ionic Bonding The chemical bonding between metals and

nonmetals   Ionic compound – composed of positive

and negative ions that are combined so that the numbers of positive and negative charges are equal.

Bonding between atoms with an electronegativity difference generally greater than 2.0

strongly attracted to each other as a result of the electrostatic forces involved.

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Let’s RememberIonic Bond = Metal + Nonmetal

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Ionic Bond Continued

In ionic bonds atoms completely give up electrons to other atoms.

There is a transfer of electrons from one atom to the other to form ionic compounds.

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Ionic Bond Example:

Lithium “gives or transfers” one electron to Fluorine! A new ionic bond is formed :

Lithium Fluoride!

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Covalent bonds

In covalent bonding, a nonmetal and a nonmetal bond together to form a compound. The compound is called a

molecule. But rather than losing or

gaining electrons, atoms now share an electron pair.

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Covalent Bonding

Covalent compound - a molecule formed by covalent bonds, in which the atoms share one or more pairs of valence electrons.

Covalent bonds have atoms with electronegativities that are about the same or with a difference that is less than 1.5.

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Octet Rule

Nonmetal atoms combine so that each atom has a total of eight valence electrons by sharing electrons.

The hydrogen atoms do not follow the octet rule. They have a total of two electrons, similar to the noble gas helium, He.

After bonding, each chlorine atom has a total of eight valence electrons surrounding it.

Cl2 PCl3 H2S

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Multiple Bonds Depending on the atoms multiple bonds between

nonmetals can form. If two atoms only share one electron pair (2 e-),

the atoms form a single bond. Ex: F2

If two atoms share two electron pairs (4 e-), the atoms form a double bond. Ex: O2

If two atoms share three electron pairs (6 e-), atoms form a triple bond. Ex: N2

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Covalent Compound Example

Carbon shares its valence electrons with oxygen’s to form two sets of double bonds

to form – Carbon Dioxide

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Metallic Properties

Electrons in metals become “delocalized electrons” from the metal atoms. The electrons move around the atoms.

This causes metal s to be good conductors of electricity.

Electricity is the flow of electrons which is already occurring in metals.

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Metallic Properties Cont.

Metals can be hammered into shape (bend) into thin sheets or other shapes. This property is called malleability.

Metals can also be drawn into wires. This is called ductility.

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Metallic Bonding

Metals hold on to their valence electrons very weakly.

Think of them as positive ions (cations) floating in a sea of electrons.