Predicting a physical state - Earth's atmosphere - GCSE Chemistry (Single Science) Revision - OCR 21st Century - BBC Bitesize (2024)

FAQs

How were oceans formed in BBC Bitesize? ›

As the Earth began to cool, water vapour condensed. formed the oceans. This process can be explained by the particle model.

The Earth's atmosphere was very different from today's - mostly carbon dioxide with very little oxygen. As plants evolved, levels of oxygen increased and carbon dioxide levels dropped. This enabled animal life to survive by using oxygen to release energy in aerobic respiration.

Through condensation the water vapor in our atmosphere was removed over time to form the oceans. Additionally, because carbon dioxide is slightly soluble in water it too was removed slowly from the atmosphere leaving the relatively scarce but unreactive nitrogen to build up to the 78% is holds today.

Its early atmosphere was probably formed from the gases given out by volcanoes. The greatest proportion of volcanic gases are made up of carbon dioxide, water vapour and ammonia. As the Earth cooled down, most of the water vapour condensed. and formed the oceans.

The Earth's atmosphere is composed of 78% nitrogen, 21% oxygen, 1% argon, and trace amounts of other gases like carbon dioxide, neon, and methane. →Why is oxygen so important in the atmosphere? Oxygen is essential for life on Earth as it is required for respiration by plants and animals.

(4.6 billion years ago)

As Earth cooled, an atmosphere formed mainly from gases spewed from volcanoes. It included hydrogen sulfide, methane, and ten to 200 times as much carbon dioxide as today's atmosphere. After about half a billion years, Earth's surface cooled and solidified enough for water to collect on it.

Steam is water vapour., which condensed. as the Earth cooled to form the oceans. Nitrogen was probably also released by volcanoes which gradually built up in the atmosphere because it is unreactive.

Developing the atmosphere - AQAHow carbon dioxide decreased. The early atmosphere was mainly carbon dioxide and water vapour. Water vapour condensed to form the oceans. Photosynthesis caused the amount of carbon dioxide to decrease and oxygen to increase.

The most abundant naturally occurring gas is nitrogen (N₂), which makes up about 78% of air. Oxygen (O₂) is the second most abundant gas at about 21%. The inert gas argon (Ar) is the third most abundant gas at 0.93%.

More than 99% of air is made of three gases: nitrogen, oxygen, and argon. Air contains other gases in very small quantities, including gaseous water, which is called water vapor. Air also contains solids and liquids. Solids in air include pollen, dust, and soot.

Which two gases make up most of the atmosphere? ›

Nitrogen and oxygen are the two main gases in our atmosphere. 78% is nitrogen and 21% is oxygen. The remaining 1% mostly contains argon, carbon dioxide, and several other gases like hydrogen, helium, neon, krypton, xenon, methane, ozone, and water vapour.

If we used a time machine to travel back to a prehistoric period, the earliest we could survive would be the Cambrian (around 541 million years ago). Any earlier than that and there wouldn't have been enough oxygen in the air to breathe.

Since the industrial revolution, humans have caused a big change in the composition of the atmosphere and significantly increased the amount of greenhouse gases in the atmosphere. These gases cause the atmosphere to trap more heat – like a greenhouse – leading to long-term changes in our climate.

Although the focus of their study was asteroid-sized bodies, the prominence of methane in particular led them to extend the work to Earth. They concluded that Earth's early atmosphere contained CH₄, H₂, H₂O, N₂, and NH₃, similar to the gas mixtures used in the Miller–Urey synthesis of organic compounds.

The atmosphere is mostly nitrogen (approximately 80%) and oxygen (approximately 20%). The remaining gases are found in much smaller proportions, such as carbon dioxide and water vapour. Oxygen in the atmosphere is essential for all living things to stay alive, and for the combustion (burning) of fuels.

The ocean formed billions of years ago.

Water remained a gas until the Earth cooled below 212 degrees Fahrenheit . At this time, about 3.8 billion years ago, the water condensed into rain which filled the basins that we now know as our world ocean.

Some scientists think that as the molten rocks on the Earth cooled off, they released steam (water vapor) into the air. This water vapor cooled off, condensed, and rained back down onto the surface of the Earth. This went on for millions of years. Scientists believe this could be one way that the oceans formed.

Volcanic eruptions spewed gases from Earth's interior to the atmosphere, a process called outgassing that continues today. Most of the gas was carbon dioxide and water vapor. The water vapor condensed to form part of Earth's oceans as the surface cooled.

Ocean Formation

The lighter rock rose and formed Earth's crust. The heavier rock sank and formed Earth's core and mantle. The ocean's water came from rocks inside the newly forming Earth. As the molten rocks cooled, they released water vapor and other gases.