Reading chemical names both ways

Science · Matter & Materials · ages 14-15

Name ______________________ Date ____________

In dinitrogen tetroxide, N2O4, what does tetra count?
- Four nitrogen atoms
- Four oxygen atoms
- Four ionic charges
What is the formula of potassium oxide?
- K2O
- KO2
- K2O2
Copper(II) chloride contains which copper ion?
- Cu+
- Cu2+
- Cu3+
Why is the formula of magnesium hydroxide Mg(OH)2?
- Magnesium needs two oxygen atoms
- Two hydroxide ions balance Mg2+
- Parentheses add extra charge
Magnesium forms Mg2+ and nitrogen forms N3-. What is the neutral formula?
- Mg3N2
- Mg2N3
- MgN
A student names NaCl sodium dichloride. What is wrong?
- Nothing, dichloride sounds precise
- Sodium should come second
- Ionic compounds skip counting prefixes
Iron(II) and iron(III) name the same ion.
Circle one: True False
Strontium forms Sr2+ and nitrate is NO3-. What is strontium nitrate?
- SrNO3
- Sr2NO3
- Sr(NO3)2

Answer key

For grown-ups. Fold this page away before handing over the rest.

Four oxygen atoms · Tetra means four, and it counts the four oxygen atoms.
K2O · Two potassium ions balance one oxygen ion, giving K2O.
Cu2+ · The numeral II reads as a 2+ charge on copper.
Two hydroxide ions balance Mg2+ · Two 1- hydroxide groups cancel one 2+ magnesium ion.
Mg3N2 · Three 2+ ions and two 3- ions both total six, so charges cancel.
Ionic compounds skip counting prefixes · Ionic names never use counting prefixes, so it is sodium chloride.
False · The numerals name different charges, so the ions differ.
Sr(NO3)2 · Two 1- nitrate groups balance one Sr2+, wrapped in parentheses.