Did you ever hear the story of Fiona Fluorine and Henry Hydrogen?
Henry was a poor boy. He was kind and friendly, but he was sad that he only had one electron. All he wanted was one more to complete his first shell. Fiona was a rich girl, she was the prettiest atom in the whole wide world, but she too needed one more electron to complete her outer shell.
Henry couldn’t give her what she needed. If he gave away his only electron, he would have nothing left. And if Fiona gave Henry an extra electron, she wouldn’t be happy either; her valence shell would be incomplete.
For months they dated other people. There was Nicole Neon, who didn’t like to talk to anyone. There was Arthur Argon who refused to pay for dinner. And there was Cody Cobalt, the lead singer of a heavy metal band. But none of them made Henry or Fiona happy.
One day, Henry stumbled across Fiona crying. She was feeling lonely and depressed. So Henry held out his hand and said to her, “I don’t have much, only one electron. But I’d gladly share it with you.” That was the moment that Fiona and Henry fell in love. They decided to be co-owners of two little baby electrons. And they lived happily ever after.
It’s not a fairy tale, it’s what happens during covalent bonding. Both atoms need more electrons to complete their valence shells, so they share! Today, in class students practiced drawing diagrams of covalent bonds. For homework, they were given four real-world compounds and they had to figure out whether each compound is covalent or ionic.