A pattern is a repeating sequence of a common variable often in an expected manner, but sometimes unexpected. In dealing with the mole in chemistry, we often have many calculations – calculating the molar mass of a substance, converting between mass and moles, and calculating the heat of enthalpy of a reaction – just to name a few. For this exercise of patterning, I will use the calculation of molar mass as my example.

Calculating the molar mass of a substance follows a particular pattern or method. Once they students learn the pattern of calculation, most of my students report enjoying this type of chemistry calculation. As indicated by the diagram below, you can calculate the molar mass of any substance as long as you know the composition of elements. The pattern is the following: multiply the number behind the element symbol (the subscript) by the atomic mass from the periodic table. Do that for each element given for the compound then add up all of the masses together. Written out...

Atomic mass x number + atomic mass x number + atomic mass x number …. etc... The pattern that some students have difficulty learning is when to multiply and when to add. Sometimes they do the opposite order or they may simply multiply all the numbers together.

Calculating the molar mass of a substance follows a particular pattern or method. Once they students learn the pattern of calculation, most of my students report enjoying this type of chemistry calculation. As indicated by the diagram below, you can calculate the molar mass of any substance as long as you know the composition of elements. The pattern is the following: multiply the number behind the element symbol (the subscript) by the atomic mass from the periodic table. Do that for each element given for the compound then add up all of the masses together. Written out...

Atomic mass x number + atomic mass x number + atomic mass x number …. etc... The pattern that some students have difficulty learning is when to multiply and when to add. Sometimes they do the opposite order or they may simply multiply all the numbers together.

In brainstorming for new patterns with this calculation, I noticed that we always use the addition symbol (+) between different elements. I've never specifically told the students that connecting pattern. When drawing out the calculation, it looked like a cross or a bridge – perhaps a bridge from one element to another! This could be an important memory cue for students to remember to use addition when going between elements. Switching to a different element, they need to make a bridge first! That's a pattern they can remember every time they do a molar mass calculation.