5 Metallic bonding

Metallic bond

Occurs between metal atoms

Metal atoms pack close together.

Many metals have an unfilled outer orbital

In an effort to be energy stable, their outer electrons become delocalised amongst all atoms

No electron belongs to one atom

They move around throughout the piece of metal.

Metallic bonds are not ions, but nuclei with moving electrons

Metallic BondingMetallic Bonding

The chemical bonding that results from the attraction between metal cations and the surrounding sea of electrons

Vacant p and d orbitals in metal's outer energy levels overlap, and allow outer electrons to move freely throughout the metal

Valence electrons do not belong to any one atom

Physical PropertiesConductivity Delocalised electrons are free to move so when a potential

difference is applied they can carry the current along Mobile electrons also mean they can transfer heat well

Malleability The electrons are

attracted to the nuclei and are moving around constantly.

The layers of the metal atoms can easily slide past each other without the need to break the bonds in the metal

Melting/Boiling points High energy is required

for the cations and its electrons to break away so BP/MP are very high.

Shiny

Light reflected by the mobile electrons causes metals to shine.

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Impurities and Melting points

An impurity disrupts the regular lattice that its particle adopts in the solid state, so it weakens the bonding. They always LOWER melting points Its often used to check purity of a known

molecular covalent compound .

Properties of MetalsProperties of Metals

Metals are good conductors of heat and electricity

Metals are malleable

Metals are ductile

Metals have high tensile strength

Metals have luster

Modifying metals

Alloys

Alloying one metal with other metal(s) or non metal(s) often enhances its properties Steel is stronger than pure iron because the carbon

prevents the delocalised electrons to move so readily. If too much carbon is added then the metal is brittle.

They are generally less malleable and ductile Some alloys are made by melting and mixing

two or more metals Bronze = copper and zinc Steel = iron and carbon (usually)

CA StandardsCA Standards

Students know atoms combine to form molecules by sharing electrons to form covalent or metallic bonds or by exchanging electrons to form ionic bonds.

Students know atoms combine to form molecules by sharing electrons to form covalent or metallic bonds or by exchanging electrons to form ionic bonds.