Entering Chemistry Expressions

There are two ways to enter chemistry expression and equations in the mathematical formula question type.

Text Mode

The system default mode is Text Mode, in which you enter symbolic or numeric math expressions in a simple keyboard notation, much like a graphing calculator.

Rule		Examples
Super Scripts and Subscripts	Enter superscripts using the caret "^" character, and subscripts using the underscore "_".	H₂O	H_2O
		H₂SO₄	H_2SO_4
Arrows in Equations	Use the text ->, <-, <=> for arrows.		->
			<-
			<=>
Other Operators	Use "*" for the center dot operator.	*	*
	Use the + sign in equations.	+	+
	No other operations are allowed in equations. You can use the "-" sign to indicate ion charges (see below).
Physical States, Ion charges, and Parentheses	Be sure to include physical states (in parentheses) if your equation requires them. Use the "+" and "-" characters for polarity and ion charges Use parentheses to clarify interpretation of groups of characters	Ca²⁺(aq) + CO₃^2-(aq) → CaCO₃ (s)
		Ca^(2+)(aq)+ (CO_3)^(2-) (aq) -> CaCO_3 (s)

Symbol Mode

For chemistry formula questions, you can also use Symbol Mode entry, which allows you to enter formulas in a WYSIWYG ("What you see is what you get") editing window. You can pick arrows, symbols or operators from a palette, and see your expressions appear as you type. Select Math Edit in the Edit Question window of the Mathematical Formula question type to display the symbol palette.

Rules for Chemistry Expressions and Equations

Spaces are ignored in expressions.
Parentheses may be used to clarify physical states, compound groupings, and application of ion charges. Use the formula preview link to preview your expressions.
In grading equations, any characters you enclose in parentheses (for example, ion charges, superscripts, subscripts, etc.) are associated with the preceding term (not the next term). Example: Pb^(2+) is Pb²⁺
For numbers that are not super or subscripted that precede a compound or element, the grader associates the number with the term that follows. Example: 2H_2O is 2H₂O