Chapter One Test (Wednesday October 3rd, at 1st Period)

Study-guide available online(through school’s website, under My Teacher’s page)

Nomenclature

Valence

Crossover rule

Polyatomic ions

Writing formulas

Naming compounds

Nomenclature

Valence charge:

Group I II III IV V VI VII VIII

Most Probable Ion

E+

(Li+)E2+

(Be2+)E3+

(Al3+)E4+ or E4-

(C4+ or C4-)E3-

(N3-)E2-

(O2-)E-

(F-)None

Nomenclature

Valence charge calculation examples:

Element Symbol Family Valence charge Representation

Silicon Si IV 4+ or 4- Si4+ or Si4-

Chlorine Cl VII 1- Cl-

Potassium K I 1+ K+

Phosphorous P V 3- P3-

Magnesium Mg II 2+ Mg2+

Nomenclature

Valence exceptions

Sometimes atoms will combine in ways that seem to defy the rules we have learned. Thus, usual electron acceptors (non-metals) can lose some or all of the electrons of the valence shell if they bond with a more electronegative atom

For example:P can be P3- when is bonded to Hydrogen to form PH3P can also be P3+ when bonded with Halogens or Oxygen (e.g. PCl3)

C can be C2+ (e.g. CO) or can also be C2- w(e.g. CaC)

Nomenclature

Crossover rule:

_Molecules are neutral (no charge)

_Valence charges must be balanced

_Number of bonds account for neutrality

For example:

Ammonia (NH3)

One N (3-) combines with one H (1+) and the resulting charge is (2-) Two more hydrogen atoms are needed to achieve neutrality The formula is then (NH3) for

Nomenclature

Crossover rule:

_Molecules are neutral (no charge)

_Valence charges must be balanced

_Number of bonds account for neutrality

Second example:

Dinitrogen trioxide Two N (each with 3+) combine with one O (2-) and the resulting charge is

(4+) Two more oxygen atoms are needed to achieve neutrality The formula is then (N2O3) for

Nomenclature

Learning Activity (Crossover rule)

Provide the right formula for the combination of:

1. Magnesium and Hydrogen

2. Calcium and Sulphur

3. Aluminum and Oxygen

Nomenclature

Learning Activity (Crossover rule with Polyatomic ions)

Provide the right formula for the combination of:

1. Aluminum and Carbonate

2. Potassium and Dichromate

3. Beryllium and Manganate

Closure and Assessment

1. Name the compounds in the handout

2. Provide the correct formula for the others

Nomenclature’s knowledge will be taken from granted after this lesson…

Chapter One Test (Wednesday October 3rd, at 1st Period)

Study-guide available online(through school’s website, under My Teacher’s page)