Module 2

Question 1

electron affinity vs electronegativity vs ionization energy

Answer 1

EA: energy released when an electron is added to an atom.

EN: The ability of an atom (in a molecule) to attract electrons

IE: energy required to form an ion
(to remove an electron from an atom)

Question 2

Determine the common oxidation state of an element if given a periodic table

Answer 2

-charge on an ion/atom
 E.g. S2-: oxidation state is -2

 O is almost always -2
 H is almost always +1

Question 3

Determine if a bond is covalent, polar covalent or ionic based on the
electronegativity of the atoms/ions

which bonds form in crystal lattice?

Answer 3

Nonpolar Covalent Bonds
-Little/no difference in EN (0< EN <0.4)
 Electron equally shared between atoms

Polar Covalent Bonds
 Medium difference in EN
(0.5< EN <1.7)
 Electron is shared in overlapping shells, spends more time
with more electronegative atom

ionic bonds
-Large difference in EN (>1.7)
 Atom with higher electronegativity
“removes” e- from other atom

ionic and polar covalent form in crystal lattice

Question 4

polymorph vs isomorph
isomorphic substitution

Answer 4

Polymorph: same chemical composition, different structure

isomorph: different chemical composition, same structure

What is Isomorphous substitution:
Substitution of elements in a crystal without affecting crystal structure

Question 5

Determine coordination number given ionic radii (I will give you ratio ranges
on a test)

Answer 5

4 -> tetrahedral
6 -> octahedral
8-> cubic

Question 6

Determine if a given ion can substitute into a given crystal lattice

Answer 6

Goldschmidt:
< 15% diff radius, same charge will readily substitute
< 15% diff radius, charges differ by one unit, coupled substitution

when deciding which will substitute:
-same charge/different radii, smaller radius forms bond
-same radii/different charge, higher charge forms bond

Ringwoods
-likely wont substitute if
EN difference > 0.1 - 0.3

Question 7

Define and describe the various types of chemical bonding

Answer 7

metallic bonding:
 s electrons in transition metals are delocalized (loosely bound) because of high energy
 Lattice sites are occupied by small positive ionic cores surrounded by delocalized electrons that are shared equally in all directions
 Cations can “roll” over each other without breaking the lattice
 This makes metals ductile and conductive

vander waals
 Weak electrostatic bonding
Always operating between all atoms,
ions, and molecules
 Overall charge of molecule is neutral,
but one end is slightly positive, and one
is slightly negative (dipole)

hydrogen bonding
A stronger version of Van der Waals forces
bc H does not have typical octet of valence electrons
 Between H and high-electronegativity elements (O, F, N)