6. Classification of Solids by Type of Attraction of Units
7. Crystalline Solids; Crystal Lattices and Unit Cells
8. Structures of Some Crystalline Solids
9. Calculations Involving Unit-Cell Dimensions
10. Determining Crystal Structure by X-Ra
When resonance structures are required for the electron-dot diagram,
you may choose any one to determine the electron-pair arrangement
and the molecular geometry.
Predicting Molecular Geometry Using VSEPR
Write the electron-dot formula from the form
Second Period Homonuclear Diatomic Molecules
In Li2, the two 1s atomic orbitals combine to form two s molecular
orbitals: s1s and s*1s.
The two 2s atomic orbitals combine to form two s molecular orbitals:
s2s and s*2s.
Six electrons occupy the orbitals in
a. Describe the process of boiling.
b. Define freezing point and melting point.
c. Define heat (enthalpy) of fusion and heat (enthalpy) of
d. Calculate the heat required for a phase change of a given
mass of substance.
Delocalized bonding is a type of bonding in which a bonding pair of
electrons is spread over a number of atoms rather than being
localized between two atoms.
A single electron-dot diagram cannot properly describe delocalized
Molecular orbitals concentrated in regions between nuclei are called
bonding orbitals. They are obtained by adding atomic orbitals.
Molecular orbitals having zero values in regions between nuclei (and
are in other regions) are called
Lets look at the methane molecule, CH4. Simply using the atomic
orbital diagram, it is difficult to explain its four identical CH bonds.
The valence bond theory allows us to explain this in two steps:
promotion and hybridization.
An ionic bond is a chemical bond formed by the electrostatic
attraction between positive and negative ions.
An ionic bond forms when one or more electrons are transferred from
the valence shell of one atom to the valence shell of another
Bonding Between Atoms
A number of compounds of the nitrosonium ion, NO +, are known,
including nitrosonium hydrogen sulfate, (NO +)(HSO4-). Use the
molecular orbitals similar to those of homonuclear diatomic molecules
and obtain the orbital diagram, elect
Electron affinity (E.A.)
The energy change for the process of adding an electron to a neutral
atom in the gaseous state to form a negative ion.
A negative energy change (exothermic) indicates a stable anion is
formed. The larger the negative number, the m
The sum of A and B is equal to the group number.
So, for an element in Group VA of the third period, the valence
Write the complete electron configuration of the arsenic atom, As,
using the building-up principle.