Marshmallow Molecules
Concepts and skills: Chemistry, covalent bonding, fine motor skills, scientific modeling
Recommended ages: 6 and up for the activity, 10 and up for the content
Materials:
Mini marshmallows
Markers
Toothpicks
What to do: Use the molecule cards to help you make a molecule model using marshmallows and toothpicks. The toothpicks represent the covalent bonds between the atoms, and the marshmallows represent the atoms! As you are making, label each marshmallow with the correct abbreviation for the atom it represents.
More Info: All atoms are made up of three parts: protons, neutrons, and electrons. Protons and neutrons are clumped together in the atom's nucleus as the positively and neutrally charged particles, respectively. Electrons are the particles in atoms that carry a negative charge. They exist in a cloud around the nucleus separated by different layers. The larger an atom, the more layers it has. The outermost layer of an atom is its valence shell. The electrons that inhabit this outermost shell are called valence electrons. Any atom is most stable when its valence shell is full, so most atoms bond with other atoms (including those of other elements) in order to satisfy the capacity of their valence shells.
Hydrogen atoms are the smallest of all elements - they only have one layer. The hydrogen atom's valence shell can house a maximum of two electrons, but by itself it only has one valence electron. Therefore, in order to be stable, it needs one more electron.
An oxygen atom is a little bit bigger than hydrogen - it has two layers. The outermost layer has six electrons naturally, but has the capacity for eight. Therefore, in order to be stable, it needs two more valence electrons.
Atoms bond with other atoms based on the needs of their valence shells. There are three main types of chemical bonds between atoms: ionic, metallic, and covalent - the latter of which we are focusing on here. Covalent bonds occur when atoms share valence electrons in order to get their valence shells to their maximum capacities. In water, an oxygen atom (has six valence electrons, needs eight) bonds with two hydrogen atoms (each has one valence electron, needs two) to create water molecules!
