Chemical Interactions

Lesson Plan - Get It!

Audio:

Everything in the world is composed of the 118 elements found on the periodic table.

Metals are on the left-hand side of the periodic table and conduct electricity. Nonmetals are found on the right side of the periodic table and can be any phase at room temperature.

These elements are all made up of the same particles but interact very differently with other elements and substances.

As you learn about the kinds of interactions between elements, record all italicized vocabulary words in your science notebook. Be sure to include the term and the meaning for each.

Elements can chemically bond together, creating compounds. Chemical bonds occur when atoms either give up electrons to other atoms or share their electrons.

Look at two different kinds of compounds, ionic and molecular.

Ionic Compounds are made of two or more elements bonded by transferring electrons. These kinds of substances are often made by combining metals and nonmetals.

This means that one element, the metal, gives its electrons to another element, the nonmetal, to form a new substance.

When an element loses an electron, it gets a positive charge. When it loses an electron, it gets a negative charge, so the positive and negative atoms are attracted to each other.

An example of this kind of bonding is table salt. Table salt is made up of the elements sodium and chlorine bonded together.

Molecular compounds are a little different because they are two or more elements bonded by sharing electrons. Molecular compounds are made up of two or more nonmetals.

An example is methane, which bonds one carbon atom with four hydrogen atoms, but all atoms share electrons to keep the bond stable.

• Can you think of some other compounds?
• What about water, H₂O, carbon dioxide, CO₂ or glucose, C₆H₁₂O₆?

Compounds and molecules are used every day by the cells in your body and the living organisms around you.

Mixtures and Solutions

Another important concept in chemistry is mixtures. Chemical reactions like those above bind two elements together to make something new. But in a mixture, no chemical bonding takes place.

Think about a fruit salad.

• How easy would it be to pick out just the grapes?
• Could you separate the oxygen from hydrogen in a glass of water?

Chemical bonds are hard to break and are not easily separated. Mixtures are two or more substances physically combined and easy to separate.

Mixtures can be heterogeneous or homogeneous and involve liquids, solids, or gases. There are many mixtures used in the kitchen!

Heterogeneous mixtures are not evenly distributed, like a box of cereal with fruit or marshmallows, where the larger pieces settle to the bottom. They do not look uniform in texture or size.

Homogeneous mixtures have a uniform distribution like Kool-Aid, sugar, and water. These appear to be the same throughout the entire sample. Another name for homogeneous mixtures of liquids is solution.

Solutions have two parts: the solute and the solvent.

The solute is the substance that will be dissolved like the Kool-Aid powder or the sugar. The solvent is the substance in which another substance is dissolved — in the Kool-Aid example, the water.

• Can you identify the solute and solvent in the above picture?

The blue would be the solute, while the water is the solvent. Eventually, the color will dissolve evenly, leaving the solution a light blue.

You have learned the basics of chemistry through this lesson.

• So, how does this apply to cell interaction function?

Well, cells must maintain specific levels of compounds and molecules to function properly.

Plants use sunlight to create glucose, an energy-rich molecule used for food. When we eat plants, we convert glucose into adenine triphosphate, or ATP, an energy molecule our cells use to transport materials across the cell membrane.

In the Got It? section, learn more about important cellular chemical interactions that help keep your cells functioning!