Understanding Material Systems, Atmosphere, and Air Composition

Understanding Material Systems and the Atmosphere

Background: A material system is a set of interrelated elements considered as a unit for study.

Homogeneous and Heterogeneous Material Systems

Material systems can be homogeneous or heterogeneous.

In a homogeneous system, different substances are not readily apparent.

A mixture is a material system (either homogeneous or heterogeneous) from which different substances can be separated by physical processes.

Solutions and Their Components

A solution is a homogeneous mixture formed by two or more substances in variable amounts, which can be separated by physical means.

In a solution, the substance present in the greater proportion is called the solvent; the others are called solutes.

Separation Techniques for Mixtures

To separate the substances composing a mixture, physical procedures that do not alter the nature of the substances are used.

Common techniques for separating mixtures include:

• Sieving
• Filtration
• Magnetic separation
• Decanting
• Crystallization
• Precipitation
• Distillation

The Atmosphere and Air Composition

The atmosphere is the outer layer of our planet. It is formed by a homogeneous mixture of gases we call air.

The most abundant gases in air are nitrogen (78%) and oxygen (21%).

Oxygen is a product of photosynthesis performed by plants and is essential for combustion and respiration.

Ozone is formed when oxygen in the air is subjected to ultraviolet rays from the sun. This gas protects living beings from the harmful effects of radiation.

Carbon dioxide is present in a small proportion in the air but is essential to life, as it is used by plants to produce organic matter in photosynthesis.

Atmospheric Layers and Functions

Three main layers can be distinguished in the atmosphere: the troposphere, the stratosphere, and the ionosphere.

The atmosphere acts as a protective filter and regulates the temperature of the Earth.

The greenhouse effect is a beneficial phenomenon that makes life possible on Earth by producing warming of the surface and allowing the planet's average temperature to reach 15 ºC.

Water vapor and carbon dioxide are the main atmospheric gases responsible for global warming.