If jealousy is one of the Ten Commandments, why is God jealous?

Question from Keri's Bible class:

If envy/jealousy is one of the Ten Commandments, why does God say his name is Jealous in Exodus?

Answer from Pastor Bob:

Read Exodus 20:1-17 again. Jealousy is not one of the Ten Commandments. When Exodus 20:5 stresses in the Second Commandment against idolatry that God is a "jealous" God, the Hebrew word used is a word only used of God. There is a different word for jealousy used in Hebrew for jealousy among people. God's "jealousy" refers to his unwillingness to share second place with anything or anyone else, because He is God and deserves to be Number One.