5 metallic bonding. metallic bond occurs between metal atoms metal atoms pack close together
TRANSCRIPT
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.
.
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.