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Homeschool Chemistry 101 – Day 2

March 13, 2014

Introduction to Chemistry

By Daniel H. Vestal, AmeriCorps Museum Investigate Lab Educator

Wednesday, March 12, 2014, was the second day of our Chemistry series. Our returning young chemists revisited the structure of an atom and practiced guessing elements. They used element boards to simulate different atomic electron configurations. Holly, our chemist/volunteer, explained how electrons are transferred and shared.

We learned how ionic and covalent bonds are formed from these shared or transferred electrons. Ionic bonding is the transfer of electrons and covalent bonding is the sharing of electrons. For instance, hydrogen is too small to be on its own, so it “wants” to share electrons with a partner. So for H2O or water, two hydrogen atoms will share their single electron with one oxygen atom. Because this creates polarity in the molecule, water is able to stick together. This led to our first experiment dealing with surface tension!

Mr. Bob, the staff educator, explained how insects such as water striders and whirligig beetles make a living using water tension to glide across the surface to catch prey. As an activity to understand the power of water tension, the homeschooled chemists inverted cups of blue tinted water, covered only with a screen, and a rubber band. To their amazement, the water stayed in the cup!

A young chemist surprised by a meniscus discovery.

A young chemist surprised by a meniscus discovery.

Another experiment allowed the scientists to use milk and food dye to demonstrate what happens when water tension fails. They poured 100 milliliters of milk into a large Petri dish while the room assistants placed a drop of food color: red, green, blue and yellow into the milk. Next, a cotton swab was dipped in liquid dish detergent. They gently touched the detergent to each drop of food color on the surface of the milk. They watched as the colors “exploded” away in different directions! This created some beautiful, liquid tie-dye creations that were preserved by placing a pre-cut piece of paper on top of the milk. The dye soaked the paper and was later moved to a spot to dry.

Food dye and milk mixture creates a tie-dye appearance.

Food dye and milk mixture creates a tie-dye appearance.

The last topic covered was phase changes in the states of matter, which are solids, liquids, and gases. A triangle is used to illustrate how solids can melt into liquids, and liquids can evaporate into a gas. When cooled the gas becomes liquid again, and with further cooling may freeze back into a solid.

What is undetectable to the human eye are the molecules bouncing around fast or slow depending on the state of matter. Gas molecules are moving around the fastest while solid molecules are moving the slowest. With gas being the fastest, the last experiment left an impact on the students.

Each student held a nearly empty soda can over a burner. When steam was seen billowing from the opening, they quickly overturned the can into an ice bath. With the rapid cooling of the less dense air inside, the much denser outside air pressing in, the can immediately and loudly imploded, much to the delight of everyone.

Class number 2 was a success due to the covalent bond between the students and instructors teaching them. It was apparent that students had become positively charged about Chemistry!  Join us for one of these classes in the Natural World Investigate lab by pre-registering on our website.

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One Comment leave one →
  1. March 20, 2014 9:46 am

    You gotta love those water striders and whirligig beetles. It’s so cool to walk on water.

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