Eleven elements-hydrogen, nitrogen, oxygen, fluorine, chlorine, helium, neon, argon, krypton, xenon, and radon-exist as a gas under standard pressure and temperature. Depending on the element, when the temperature or pressure is raised or lowered, then they will shift into another state.
Elemental Gases
- Hydrogen (H)
- Nitrogen (N)
- Oxygen (O)
- Fluorine (F)
- Chlorine (Cl)
- Helium (He)
- Neon (Ne)
- Argon (Ar)
Liquid oxygen - Wikipedia; compare to oxygen gas, in the ampule. You can't see the blue color in the gas sample. And even if our eyes could see that kind of light, there wouldn't be any for use to see oxygen with. Therefore, we cannot see oxygen.
Fire is made up of many different substances, so it is not an element. For the most part, fire is a mixture of hot gases. Flames are the result of a chemical reaction, primarily between oxygen in the air and a fuel, such as wood or propane. Or, you can say it's mostly gas, with a smaller amount of plasma.
Gases are air-like substances that can move around freely or they might flow to fit a container. They don't have a shape either.
All gases are transparent, and most are colorless.
Tell students that gases are made of molecules but that the molecules are much further apart than the molecules in liquids or solids. Since the molecules of a gas have mass and take up space, gas is matter. Students may have difficulty imagining that gases have mass.
Examples of Gas to Liquid (Condensation)
Water vapor to dew - Water vapor turns from a gas into a liquid, such as dew on the morning grass. Water vapor to liquid water - Water vapor forms water droplets on the glass of a cold beverage.Report: The World Will Run out of Breathable Air Unless Carbon Is Cut. A new study finds that unabated greenhouse gas emissions will cripple ocean phytoplankton's ability to produce oxygen.
Layers of Earth's Atmosphere. Layers of the atmosphere: troposphere, stratosphere, mesosphere and thermosphere. Earth's atmosphere has a series of layers, each with its own specific traits. Moving upward from ground level, these layers are named the troposphere, stratosphere, mesosphere, thermosphere and exosphere.
Gases in Earth's Atmosphere
Nitrogen and oxygen are by far the most common; dry air is composed of about 78% nitrogen (N2) and about 21% oxygen (O2). Argon, carbon dioxide (CO2), and many other gases are also present in much lower amounts; each makes up less than 1% of the atmosphere's mixture of gases.Blue light is scattered in all directions by the tiny molecules of air in Earth's atmosphere. Blue is scattered more than other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time. Closer to the horizon, the sky fades to a lighter blue or white.
According to NASA, the gases in Earth's atmosphere include:
- Nitrogen — 78 percent.
- Oxygen — 21 percent.
- Argon — 0.93 percent.
- Carbon dioxide — 0.04 percent.
- Trace amounts of neon, helium, methane, krypton and hydrogen, as well as water vapor.
Specific gases
| Gas | Colour |
|---|
| Chlorine | yellow shoulder |
| Helium | brown shoulder |
| Hydrogen | red shoulder |
| Nitrous oxide | blue shoulder |
Nitrogen and oxygen are by far the most common; dry air is composed of about 78% nitrogen (N2) and about 21% oxygen (O2). Argon, carbon dioxide (CO2), and many other gases are also present in much lower amounts; each makes up less than 1% of the atmosphere's mixture of gases. The atmosphere also includes water vapor.
Wind is caused by differences in the atmospheric pressure. When a difference in atmospheric pressure exists, air moves from the higher to the lower pressure area, resulting in winds of various speeds. On a rotating planet, air will also be deflected by the Coriolis effect, except exactly on the equator.
Air is a mixture of gases, 78% nitrogen and 21% oxygen with traces of water vapor, carbon dioxide, argon, and various other components. We usually model air as a uniform (no variation or fluctuation) gas with properties that are averaged from all the individual components.
Red-green and yellow-blue are the so-called "forbidden colors." Composed of pairs of hues whose light frequencies automatically cancel each other out in the human eye, they're supposed to be impossible to see simultaneously.
The human eye can only see visible light, but light comes in many other "colors"—radio, infrared, ultraviolet, X-ray, and gamma-ray—that are invisible to the naked eye. On one end of the spectrum there is infrared light, which, while too red for humans to see, is all around us and even emitted from our bodies.
