Transcript Metallic Bond - Chemactive Online Help

Metallic Bond
IB
Formation of metallic bond
• the metal atoms "lose" one or more of
their outer electrons
• These electrons become delocalized, and
free to move throughout the entire
metal.
• These negative delocalized
electrons hold the metal cations together
strongly.
Metallic bonding in sodium
• Each positive centre in the
diagram represents all the rest of
the atom apart from the outer
electron,
• but that electron hasn't been lost it may no longer have an
attachment to a particular atom,
but it's still there in the structure.
• Sodium metal is therefore written
as Na - not Na+ or potassium
metal is written as K but not K+.
Metallic bond definition
• It is the attraction force between
positive metal ions and the
delocalized electrons.
Metallic bond properties
• Unlike ionic bonding, distorting the atoms does not cause
repulsion so metallic substances are:
•
•
•
•
ductile (can be stretched into wires)
malleable (can be formed into shapes).
Heat and electricity conductivity.
The free moving electrons also allow for high thermal
conductivity, and the electrons can carry the heat
energy rather than it being transferred slowly through
atoms vibrating.
Electrical conductivity of metals
•Electric current is the flow of electrons in a wire.
•In metals, the outer electrons of the atoms belong to a
‘cloud’ of delocalised electrons.
• They are no longer firmly held by a specific atom, but
instead they can move freely through the lattice of
positive metal ions. Normally they move randomly.
•when the wire is connected to a cell, they are pushed
away from the negative terminal and drawn to the
positive one. The cloud of electrons drifts through the
wire