Crystalline solids

What are ionic solids made of

Positive and negative ions held together in a crystal lattice strucutre

How does an ionic bond

The electrostatic attraction between positive and negative ions ioccurs when eectrons are tranferred from 1 atom to another

2 factors affecting the strength of an ionic bond

Known as charge density
1)interionic distance - smaller distance = stronger bond
2) ionic charge

Macroscopic properties of ionic solids

High mp and bp
Brittle
Dont conduct current when solid bcelectrons are held firmly to ions
In liquid and dissolved state, current can flow bc ions are free to move
soluble in water bc water is polar so separates ions

WHy are ionic solids brittle

when ions of the same charge are forced into positions opposite each toher, their repulsion causes splitting

What are the lattice points and bonds in an ionic solid

Latice points are occupied by ions and the bonds conecting htem are ionic

WHat are the lattice points and bonds in molecular and atomic solids

Crystals whos lattice points are occupied by neutral molecules held togethr by weak intermolecular forces
Molecules or atoms int eh crystal can by non-polar or polar

Intramolecular forces of molecular and atomic solids

colvalentbonds withint he moleculare very strong

Intermolecular forces of molecular and atomic solids

forces between molecules, holding them together in the crystal, are very weak

Macroscopic properties of molecular and atomic solids

Low melting points
poor conductors of electricity or heat- e- not free

2 factors affecting te strength of intermolecular forces in molecular and atomic solids

1) molecular mass

• Greater mass= larger #of e- = stronger disperison
  2) polarity of molecule
• polar molecules have similar dispersion forces with additional dipole forces

BOnds and lattice points of netwrok solids

Lattice points are occupied by atoms held together by single covalent bonds

3D network solids

Diamond consists of C atoms connected tetrahedraly by covalent bonds
ex. SiO2, SiC, Cdiamond, Cgraphite, Si

Macroscopic properties of diamond

very hard
high melting point
non-conductor of electricity

2D network solids

Graphite consists of C atoms connected by covalent bonds in 2D sheets or layers
ex. mica

Types of bonding in 2D network solids

-Strong covalent bonds with each layer lead to high melting point
-weak disperiosn forces between layers
-Conducts electricity

1D network solids

-Form long chains with strong covalent bonds within a chain leading to high mp and strong along its length
-Weak dispersion forces between chains leading to fibrous and easily peeled

Metalic structure lattice points and bonds

Lattice points occupied by metal and held together by metalllic bonds

What are metallic bonds

In metals, the valence electrons arent held storngly to the nucleas so they are delocalized and move easily through the outer shell regions of the atom

• the atoms is now a metallic ion
  The attraction between the + charged metallic ions and the movild delocalized valence electrons is now a bond

Electron sea model

Metallic bonding is represented by the electron sea model bc electrons move continuously from one metallic ion to another

Strength of metallic bonds in transition metals

have additional delocalized electrons(highest mp and strongest bonds) available for even stronger bonds

Strength of metallic bonds

increases iwth the number of valence electirons
bc there are more mobile elctrons and the nuclei have greater charges

Macroscopic properties of metallic solids

-good electrical and thermal ocnductivity
-ductile
-malleable
-lustrous
-photoemission

Conductivity of metallic solids

Due to the high mobility of valence electrons

Malleability and ductility of metallic solids

Can be drawn out as a wire and can be lattened into sheets because atoms are not restricted to one position by a fixed bond so the electrons are free to move with the atoms under stress

Lustrousness of metallic solids

Reflects all original light because the high mobility of valence electrons permits them to oscillate iwth and re-emit the same frquency as the incident radiation

Photoemission of metallic solids

light can eject electrons from soem metal surfaces tdue to low ionization energy of some metals and high mobility of electrons