Hydrocarbon Chains and Rings (samples)

In Hydrocarbon Chains and Rings:

Students learn about:

electronic structure of atoms (review)
building wooden models of H2O (review)
hydrocarbons
building wooden models of CH4 (methane)
3D structure of hydrocarbons
isomers
hydrocarbon stick diagrams
hydrocarbon rings
polyethylene
polypropylene

Equipment provided:

1. eight 1 ½” balls (2 holes (oxygen), seven with 4 holes (carbon))
2. sixteen 1” balls with bonds attached (glued) (hydrogens)
3. seven long bonds (dowels)

Atomic Chart
Electron Diagrams for Atoms worksheet

Excerpts from Hydrocarbon Chains and Rings:

What is a hydrocarbon?

A hydrocarbon is a molecule made from combining two different elements. Can you guess from its name which elements those might be?

Yes, hydrocarbons are molecules made from the elements: hydrogen and carbon.

Why is it important to know about hydrocarbon chains and rings?

Our bodies and most of the substances around us have hydrocarbon chains and rings as their basic skeleton: – fats, sugars, proteins, DNA, the membranes of our cells, cholesterol, rubber soles and tires, medicines, the colors and scents of flowers, the flavors of lemons and limes and vanilla, motor oil, gasoline, diesel, plastics, … The list is endless.

Let’s look more closely at chains and rings of carbon atoms. Carbon is one of the rare atoms that can bind to each other to form chains:

or rings:


A Brief Review of Electronic Structure

Those who studied the Atoms and Molecules units in this series know about the electronic structure of atoms.
The nuclei of atoms are important, of course, but chemistry depends upon the electrons. Electrons are arranged in layers which chemists call shells:


Neon Atom

Neon, for example, has 10 electrons and they are arranged in two shells – 2 electrons in the first shell and 8 electrons in the second shell. As you’ll see shortly, neon has both electron shells filled, but most atoms don’t have filled shells. These are the atoms that form molecules and are much more important in chemistry. We’ll build a few of these atoms and molecules and then concentrate on hydrocarbon chains and rings.

First we will build atomic models on paper using the Atomic Chart and the Electron Diagrams for Atoms worksheet. After we understand the paper models we’ll study the wooden 3D models of the same atoms and use these models to build molecules.

I know you want to start building things immediately, but before we can make models, we need to review the rules for building atoms.

The Atom Rules:

Rule 1: Each atom has an atomic number which is equal to the number of protons in its nucleus. Atoms usually have the same number of electrons as protons. For example, an atom with 2 protons in its nucleus will also have 2 electrons.

Rule 2: The simple atoms we will study have their electrons in two shells. The innermost shell of an atom can contain no more than 2 electrons. The next shell of an atom can contain no more than 8 electrons.

Rule 3: Electrons don’t like to be crowded together. Whenever possible, they must be separated within a shell. If there are more than 4 in the shell, some will pair up.

Rule 4: Atoms like to have their outer shells filled with electrons. As you saw when you studied Molecules, atoms make sure their outer shells are filled by sharing, taking, or giving away a few electrons.