Dichotomous key essay sample

Your task is to create a dichotomous key to help students WRITE FORMULAE for all the different types of compounds that we have learnt this unit. Your audience will be students beginning their grade ten who have minimal knowledge on writing chemical formulas. They are able to: • Read the periodic table and identify metals, metalloids, and non‐metals • Identify polyatomic, but don’t have them memorized • Read the oxidation states (charges) on the periodic table However, you should assume that they have no knowledge on ionic and covalent bonds, criss‐cross rule, prefixes, acids, and adding or subtracting oxygen atoms from polyatomic ions.

Instructions: • Use only yes/no type of question (there must be two answers‐ yes or no). • • • • • Questions must relate to the compound name Start by asking a single general question that divides the compounds into two categories Continue questioning and dividing until each type of compound is by itself Then state the rules and instructions of how to write the formula from the name You may reconnect branches if rules are similar

Look on angel for examples of compounds that you should be able to successfully write formula for using your dichotomous key.

Criteria 1) Classification of compounds (Thinking) ‐ All types of compounds are represented /4 ‐ Classifications are correct and logical /5 ‐ Questions are effective in separating chemical names, use the least repetition possible, and contains yes/no answers only /4 2) Instructions (Communication) ‐ Clear, concise and accurate /4 ‐ Provides clear legend where necessary /2 3) Appearance (Communication) ‐ legible, neat and visually appealing /1 Total : T: /13 C: /7