Elements

Lesson Plan - Get It!

Audio:

Colors are defined by the wavelength of light moving through the air.

The wavelength is the distance between waves, kind of like the distance between two waves on a slinky.

Waves that are closer together produce colors like violet, whereas waves that are further apart produce colors like red. Each color has a unique wavelength.

Chemical elements are very similar, because each element is unique, but they are made of the same stuff.

We know that atoms are the building blocks of our world, and each atom can be identified as a specific element based on the number of protons found in the atom. An element is defined as a substance that cannot be simplified and retains unique characteristics.

For example, while we know that atoms are made up of subatomic particles, and all of these particles function the same way, each element has a unique combination of particles.

Every atom of sodium will have 11 protons, which is also the atomic number of sodium. As you can see in the periodical table above, the atomic number is listed in the upper left-hand corner of the box.

There are, as of 2017, 118 elements in our world, and they make up everything around us. Most of these elements are naturally-occurring, but some have only been made in a laboratory setting. These elements can combine to make familiar substances.

For example, water is made up of hydrogen and oxygen, while sugar contains carbon, hydrogen, and oxygen.

The most common elements in the entire universe are hydrogen and helium, because they comprise stars! On the earth, oxygen and silicon are most abundant in the crust, while our bodies are made of hydrogen, carbon, nitrogen, oxygen, phosphorus, and calcium.

Scientists have even compared atoms found on other planets. Iron atoms collected from Mars are identical to the iron atoms we have on our planet.

• Have you noticed that many elements have letter abbreviations?

We use chemical symbols to refer to elements. These symbols are based on the Latin name for the element, so they might not always make sense with the English name. Iron is a great example — its chemical symbol is Fe because the Latin name is Ferrum.

Chemical symbols can be found on the periodic table along with the atomic number and atomic mass.

Each element has particular characteristics that are based on the atomic structure. These characteristics include color, magnetism, density, freezing point, and many others.

Cobalt is an element with 27 protons, and a very beautiful blue color.

Copper has 29 protons, and is a metallic orange color. The atomic structure can really change the physical and chemical properties of an element!

The freezing point is the temperature at which the element moves from a liquid to a solid, and is different for each element. The freezing point of cobalt is 2,723 degrees Fahrenheit, while copper freezes at 1,984 degrees Fahrenheit. This difference results from forces acting on the atoms.

When considering which elements to use for a specific function, scientists take these characteristics into consideration. Some elements are radioactive and can be used in medicine to observe changes in the body. Others are used to ignite neon lights and let us know that our favorite store is open. We consume many elements, while others are considered toxic.

1. On a sheet of paper, summarize what you have learned about elements, thinking about how many elements you come into contact with each day.
2. Then, reflect on this question:

• How might changes to the atomic structure impact the characteristics of an element?

In the Got It? section, you will learn more about uses of elements in our world.