Arrival Craft: Dotty pictures of atoms (sticking on big red protons and small blue electrons). atomssheet
Introduction: We’re going to look at batteries today.
Does anyone know what batteries have inside?
Lots of batteries have acid inside them. That’s the kind that we’re going to be looking at today.
Acids have easily detached hydrogen ions. When the the zinc is in the acid, some of the zinc nuclei are attracted to the positively charged hydrogen ions. So, they leave the zinc strip.
The zinc strip now has extra electrons (which are negatively charged) so the entire strip becomes negatively charged.
Copper holds on more tightly to its electrons than zinc does, so the zinc strip becomes more negative than the copper strip does. If we connect the two metal strips together, then electrons can flow from the more negative zinc strip to the less negative copper strip, making an electrical current.
There won’t be enough electrical energy to power a lightbulb, but we should be able to get enough to see on our multimeters.
Individual Task: Using zinc and copper nails and lemon juice, make simple batteries, and read the currents using multimeters. batteries
Second Part: Batteries are a way of storing energy. We call this type of energy Chemical Potential Energy.
Strictly speaking, what we have each made so far is called a cell. A battery is a row of cells connected together. Let’s connect all our cells together to make a big battery and see how much power we generate.
Break for snack
Gather Together: It was Allesandro Volta who made the first chemical batteries, he used discs of copper and zinc, with brine as an electrolyte. But, there were batteries before this.
The first batteries, which were made by Ewald Georg von Kleist and by Dutch scientist Pieter van Musschenbroek of Leiden (Leyden), were charged by static electricity.
We’re going to finish today with a quick look at static electricity.
It follows the same principle as the chemically induced electric current we made with acid: you knock off electrons and create an object with a positive charge. But, it’s very easy and doesn’t require any acid!
Show static electricity model and hand out bits and pieces so children can make their own.