Characteristics and Roles of Air 3rd Grade Science

Air refers to the mixture of gases in the earth's atmosphere, so air belongs to the mixture, which is mainly made up of nitrogen.

Oxygen, noble gases (helium, neon, argon, krypton, xenon, radon, gas O, carbon dioxide.

and other substances (such as water vapor, impurities, etc.). Among them, the volume fraction of nitrogen is about 78%, the volume fraction of oxygen is about 21%, the volume fraction of noble gases (helium, neon, argon, krypton, xenon, radon) is about, the volume fraction of carbon dioxide is about the latest data), and the volume fraction of other substances (such as water vapor, impurities, etc.) is about.

The composition of air is not fixed, and as the altitude changes, the air pressure changes, and the proportion of air composition also changes. But air was long thought to be a single substance, until later the French scientist Lavoisier.

Experiments first led to the conclusion that air is composed of oxygen and nitrogen. At the end of the 19th century, scientists discovered through a large number of experiments that there were rare gases such as helium, argon, and xenon in the air.

The characteristics and effects of air are in the third-grade textbook, so you have to think about it first. The air of the air is a colorless, odorless, transparent gas, which has the effect of fueling combustion. If the air is removed, the object cannot burn, and at the same time it can.

It contains other substances such as nitrogen, oxygen, and carbon dioxide, which need to be broken down by the children. Or it's a PPT presentation.

Characteristics and functions of air Air is a colorless and odorless gas, and its function is to enable the survival of people, animals and things.

The air goose is colorless and odorless, and its role is to maintain ecological balance!

The characteristics and functions of air in the third grade are generally mainly to tell him that the air can transmit a substance and that there is some oxygen in the air, mainly according to the curriculum standards and lesson plans.

Air, it's the colorless and odorless gas, and then we have to be indispensable.

Joon 3rd grade science advice etc give me the official air, I'll consult the characteristics of the air again, 3rd grade.

Characteristics of air: it occupies space, has no fixed shape, is fluid, is easily compressed, and has weight. The air is transparent, colorless and odorless, it is mainly composed of nitrogen and oxygen, which has an important impact on human survival and production.

Air is a colorless, odorless, and transparent gas that is directly invisible, intangible, and odorless. An ordinary plastic bag can be prepared. Tie the bag tightly with your hand. You can see the pockets bulging. It's air.

Occupy space. Place a plain napkin in a beaker.

Middle. Then place the beaker upside down in the sink and submerge it all. Take it out, why this paper is not wet, it turns out that the beaker is filled with air, and the air occupies the space, providing a dry environment for this paper.

will flow, one beaker is filled with air, and the other beaker is filled with water. When we tilt the beaker filled with air, since the air is lighter than the water, the air will flow upwards into the water-filled beaker above, and the water will be driven out. Air flows upwards in water.

The air is easily compressed with a regular syringe.

Pump in air and water separately, then plug the nozzle with your fingers, press the piston with the same size and pull the piston upwards. The space occupied by air can be compressed or enlarged, it has no fixed shape and volume.

The characteristics of the 3rd grade science air are as follows:

1. In its natural state, the air is colorless and odorless. It is mainly composed of nitrogen and oxygen, which has an important impact on the survival and production of human beings.

2. Due to the strong attraction of the earth, 80% of the air is concentrated in an average range of 15 kilometers above the ground. This layer of air has a great impact on human life and production activities. What people often refer to as air pollution refers to air pollution in this range.

3. Air is a necessary condition for the survival of animals and plants on the earth, and animal respiration and plant photosynthesis are inseparable from air; The atmosphere can keep the temperature on Earth relatively stable, and without an atmosphere, the temperature would be high during the day and low at night.

4. The ozone layer can absorb ultraviolet rays from the sun and protect life on the earth from harm; The atmosphere can prevent high-energy particles from space from entering the Earth too much, preventing meteorites from hitting the Earth, because meteorites can both slow down and burn when they rub against the atmosphere.

5. Air is a mixture, which is mainly composed of nitrogen, oxygen, rare gases (helium, neon, argon, krypton, xenon, radon, gas Ao), carbon dioxide and other substances (such as water vapor, impurities, etc.).

The role of air:

1. Air can support combustion (because there is oxygen in the air).

2. Air is a necessary condition for the survival of animals and plants on the earth, and animal respiration and plant photosynthesis are inseparable from air for respiration.

3. The air is under pressure, and the production and life of human beings under pressure play an important role.

4. The air is buoyant, and it depends on his birds and airplanes to fly in the air.

5. The atmosphere can block all kinds of rays from the universe and protect the creatures on the earth from them.

Composition of air:

Air is a mixture of many gases. Its constant components are oxygen, nitrogen, and noble gases, and its variable components are carbon dioxide and water vapor, and their levels in the air vary slightly depending on geography and temperature.

As for the indefinite components of the air, it varies from region to region, for example, sulfur dioxide is contained near metallurgical plants, chlorine is found near chlor-alkali plants, and so on. In addition, there are trace amounts of hydrogen, ozone, nitrous oxide, methane and, to a lesser extent, dust in the air.

Experiments have shown that the percentage of constant components in the air is almost constant up to 100 km above the ground. In terms of volume content, oxygen accounts for about it, nitrogen accounts for about it, and noble gases about it.

The above content reference: Encyclopedia - Air.

The knowledge points of water and air in the third grade science are as follows:1. Water can be touched, but air can't.

2. Water is a liquid and air is a gas.

3. Water is one of the most common substances on earth. 72% of the Earth's surface is covered by water. It is an important resource for the survival of all life, including inorganic chemistry and human beings, and it is also the most important component of living organisms.

4. Air is layered on the surface of the earth, transparent, colorless and odorless, it is mainly composed of nitrogen and oxygen, which has an important impact on the survival and production of human beings.

5. Oxygen in the air is necessary for all aerobic organisms. All animals need to breathe oxygen, as do the respiration of green plants. In addition, green plants use carbon dioxide from the air for photosynthesis, and air is almost the only carbon dioxide required by all plants**.

Air has mass.

Science Experiments for Elementary Schools:

Adjust the scales; Blow two balloons of the same size on either side of the scale and let them balance; Puncture one with a needle and tilt the scales to the other side; Prove that the air has quality.

Air stratified over the earth's surface, transparent, colorless and odorless, it is mainly composed of nitrogen and oxygen, which has an important impact on human survival and production.

Air refers to the mixture of gases in the earth's atmosphere, so air is a mixture, which is mainly composed of nitrogen, oxygen, noble gases (helium, neon, argon, krypton, xenon, radon), carbon dioxide and other substances (such as water vapor, impurities, etc.).

Air quality is judged by the concentration of pollutants in the air, and its quality reflects the level of air pollution.

Air pollution is a complex phenomenon, and the concentration of air pollutants at a given time and place is affected by many factors. Urban development density, topography and meteorology are also important factors affecting air quality.

The concentration of negative oxygen ions is one of the signs that the air is bad. According to the standards of the World Health Organization, when the concentration of negative oxygen ions in the air is higher than 1000-1500 per cubic centimeter, it can be called "fresh air".

Air pollution sources can also be divided into two categories: natural and man-made. Natural pollution sources are formed due to natural causes (such as volcanic eruptions, forest fires, etc.), and man-made pollution sources are formed due to people's production and living activities.