Beaker BreakerDraw the Lewis structure of

the following polyatomic ions:• nitrite ion

• sulfite ion

Metallic Bonding

6-4

Do metals have “few” or “many” valence electrons?

• How do they achieve “stability” ?

Metallic Bond Model

• metals have very few electrons in their highest E level

• metals frequently have many vacant d-orbitals just below the outer level

• vacant orbitals of adjacent atoms overlap which allows these loosely held e-s to roam freely

Metallic Bond Model (con’t)

• “delocalized electrons” - e-s don’t stay in one locality like…– covalent bonding: stay in the overlapping of the

shared orbitals– ionic bonding: e-s are bound to an ion within a

crystal lattice

• mobile electrons form a “sea of electrons”

Metallic Bonding

• the chemical bonding that results from the attraction between metal atoms and the surrounding sea of electrons

• mutual sharing of many e-s where each atom contributes its valence e-s which are then free to move about the mostly vacant outer orbitals of all the metal atoms

So…why are metals….

• good electrical conductors?

• good thermal conductors?

• shiny?

• malleable/ductile?

Metallic Properties

• High electrical & thermal conductivity – due to high mobility and delocalization of e-s

• Luster (shine)– metals absorb E and become “excited” very

easily because many of their orbitals are separated by extremely small ∆E…shine occurs when photons are emitted when excited e-s

return to ground state

Metallic Prop. (con’t)

• Malleability (ability to be hammered/beaten into thin sheets) and ductility (ability to be drawn, pulled, or extruded to produce wire) because metallic bonding is the same in all directions and a shift in layers of atoms is inconsequential

What determines if a metal is “strong” or not?

Metallic Bond Strength

• Expressed in the heat of vaporization value where the bonded atoms in the metallic solid state are converted into indiv. metal atoms in the gaseous state (usually↑heat of vap, the ↑ the bond strength)

• Determined by – strength of nuclear charge & # delocal. e-s

What is the difference between…- Bond energy ??- Lattice energy ??- Heat of vaporization ??

Hint:

• What kind of bonding is generally involved when this term is used?

• Is energy being added or taken away?

What is the difference between…- Bond energy ??- Lattice energy ??- Heat of vaporization ??

• Bond energy: E added to break a covalent bond• Lattice energy: E released when ionic cmpds

are broken down into atoms• Heat of vaporization: E added when bonded,

metallic, solid atoms are broken into indiv gaseous atoms