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Ruberic for Halogens

Rubrics for assessing Class work

 

 

Criteria

Exemplary

(5 pts)

Highest category of CIE level work

Adequate

(4or 3 pts)

Acceptable to examiner

Needs improvement

(2 or 1 pts)

Require more description

No relevant answer

(0 pts)

 

Justifying the position of Halogens

Their electron configuration, properties and their non-metallic behavior in ionic and covalent bonding

Describe physical properties without reasoning their position in the periodic table

Can tell the charge on ion

Tell only as non-metals

Apprehending and exploring the reactivity of Halogens

Conceptual response to the teacher’s question regarding displacement of Halogens in a chemical reaction

Can give the answer due to their position in the Group 7

Tell only the name of reactive Halogen without reasoning

No response

Define terms   like sublimation, displacement or reactivity

All definitions and examples of the types of reactions are accurate and organized

Some definitions and examples of the types of reactions are accurate

 

 

Most definitions and examples of the types of reactions are not accurate and not organized

No relevant answer

Describing a reaction

Types of reactions are summarized with descriptions and are in detail

 

Types of reactions are summarized with descriptions and are in partial detail

 

Types of reactions are summarized  with descriptions but no detail

Types of reactions are only enumerated

 

Name of checker: _____________                                                                                                                 Total points: ________

 

Student’s name whose work is assessed: ___________                                                                               Date: ____________

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Posted by on April 3, 2014 in Uncategorized

 

Oxidation State

Rules to work out oxidation states:

ž  An atom in its elemental state has an oxidation number of 0.

ž                               Na,  H2, Cl2, S, Xe

ž  2.         An atom in a monoatomic ion has an oxidation number identical to its charge.

            Na+ , Ba+2,  Al3+  ,Br–  , S2–

ž  The oxidation number is equal to the charge on the monoatomic ion.

ž  3.         An atom in a polyatomic ion or a           molecular compound usually has the      same oxidation number it would have if    it were in a monoatomic ion.

ž  a. Elements to the left on the periodic table are “cation like” and have positive oxidation numbers

b. Elements to the right on the periodic table are “anion like” and have negative oxidation numbers.

 

c. Oxygen often has a –2 oxidation number, but can have a –1 oxidation number in the peroxide ion,

 

H2O (O –2 oxidation number)

HOOH (O –1 oxidation number)

 

d. Halogens usually have an oxidation number of –1,

 

 
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Posted by on January 22, 2014 in Uncategorized