Judging by the cheers and sounds of amazement coming from Pat Gaines' fourth-grade classroom, one would think they had a magician visiting for the day. But no magic was taking place, just chemistry.

Several members of Alpha Chi Sigma, Cornell's chemistry fraternity, went to Belle Sherman Elementary School, Feb. 11 and 12, to teach the children about batteries and metals, and the metals' chances of gaining or losing electrons in relation to each other.

"Since I'm an Ithaca native, I thought it would be cool to do something to give back to the Ithaca schools," said Aaron Bloomfield '08, a member of the fraternity's outreach committee. He noted that several demonstrations in his early years of schooling were very influential in his wanting to become a chemist.

Bloomfield used such simple electrochemistry experiments as showing displacement reactions -- when a neutral metal and a charged metal exchange charges -- to demonstrate how four metals -- aluminum, copper, iron and silver -- react with solutions of each other. By placing pieces of each metal in a charged solution of the others, the students could see which metals reacted with the others. Aluminum, for example, did not react with anything, but the copper solution reacted with iron and aluminum. Some reactions gave off enough heat to boil the water. Others caused the metals to visibly change.

After seeing which metals reacted, the children were able to explain which metals were more likely to gain or lose electrons in relation to the others, with aluminum being the most likely to lose electrons and silver being the least likely.

"I was very impressed with what they took away," Bloomfield said. "Some metals are stronger than others in their attraction of electrons. [I] couldn't have said it better myself."

The next day he had the children make their own batteries by using different types of metals inserted into potatoes. A battery uses a single displacement reaction that occurs "when the reacting metals are separated by a wire. So the electrons are transferred through the wire, and instead of getting heat you get electromotive force," he said.

Each group of children used a different combination of metals to make their batteries and were able to measure the voltage each battery produced. They were able to see firsthand that the voltage generated depended on which metals were used and how large a difference there was in their ability to gain or lose electrons.

While none of the potatoes reached nine volts, the amount of electricity produced by the battery, Bloomfield showed -- using a student's suggestion -- that when he joined two potato batteries together, the more "batteries" you connect, the greater the total amount of electricity produced.

"I love having Cornell students come to my classroom to share their expertise," said Gaines. "They bring an enthusiasm for the subject matter that only a specialist can create. I also appreciate their youth -- I think that it inspires the young students and opens their minds to potentialities that they had not been exposed to before."

Alpha Chi Sigma is a professional, co-ed national chemistry fraternity, said Lauren Messina '08, master alchemist of the fraternity. Members conduct volunteer demonstrations in the community and sponsor a lecture series on campus.

"We like to do outreach in the community when we can, and this seemed like a good opportunity," Messina said.

Sara Gorecki '08 is a student intern at the Cornell Chronicle.