Integrated Science, Secondary Grade, Chapter 2 - Lesson 3

Integrated Science st TheII 1 Secondary Grade Chapter 2 Lesson 3 : Chemical Reactions in the Atmosphere The atmosphere is not just a shield that protects the Earth, it is the scene of complex chemical reactions t...

Integrated Science st TheII 1 Secondary Grade Chapter 2 Lesson 3 : Chemical Reactions in the Atmosphere The atmosphere is not just a shield that protects the Earth, it is the scene of complex chemical reactions that play a crucial role in our daily lives. From the formation of ozone that protects the Earth from ultraviolet radiation to air pollution that threatens the health of humans and other living things. These chemical reactions in the atmosphere affect air quality, climate, and public health. In this lesson, we will learn about how these reactions occur and their effects on the environment and humans. Chemical in the atmosphere : 1. Ozone Formation : The ozone molecule (O₃) consists of three oxygen atoms. Ozone is formed in the stratosphere of the atmosphere through the action of ultraviolet (UV) radiation from the sun on oxygen molecules (O₂) as follows: 1. Photo dissociation: UV radiation with a wavelength less than 240 nm breaks the covalent bond in the oxygen molecule (O₂), resulting in the production of two individual oxygen atoms (O). 2. Ozone Formation: An individual oxygen atom then reacts with an oxygen molecule (O₂) to form an ozone molecule (O₃). The importance of ozone: Ozone acts as a shield that protects the Earth from harmful ultraviolet radiation. Without this layer, life on Earth would be severely damaged by these rays. 01063200774 50 ENG / Mahmoud FATHY  Integrated Science st TheII 1 Secondary Grade The negative impact of ozone in the troposphere: Air pollution: Ozone gas in the troposphere forms part of smog. Smog is formed when ozone, nitrogen oxides (NOₓ), sulfur dioxide (SO₂), and fine particles react in the presence of sunlight. Health issues: Ozone can cause health issues such as eye, nose, and throat irritation, breathing issues, asthma, and damage to the lungs. Environmental effects: Ozone can cause damage to plants and agricultural crops, affecting their growth and quality. It can also cause corrosion of materials such as plastics and rubber. Greenhouse gas effect: Ozone is one of the greenhouse gases in the troposphere that contribute to the greenhouse effect. This can lead to climate changes such as rising temperatures and changes in weather patterns. 2. Air Pollution Air pollution can originate from natural sources, such as volcanoes and wildfires, or from human activities, such as factory smoke and vehicle emissions. Air Pollution and Climate Change Some air pollutants, like carbon dioxide (CO₂) and other greenhouse gases, contribute to global warming, leading to significant climate changes such as polar ice melting and rising sea levels. Air Pollution and Human Health 1. Respiratory Diseases: Air pollution is linked to various respiratory diseases, including asthma, bronchitis, and allergies, as well as cardiovascular diseases like heart disease and stroke. 2. Child Development: Exposure to air pollution can negatively affect brain development and overall growth in children. 3. Cancer Risk: Some pollutants, such as benzene and arsenic, are associated with an increased risk of certain types of cancer. 01063200774 51 ENG / Mahmoud FATHY  Integrated Science st TheII 1 Secondary Grade Air Pollution and Ecosystems Air pollution can lead to a loss of biodiversity in ecosystems. 1.Effect on Plants: Tropospheric ozone can damage plant leaves, reducing their ability to perform photosynthesis. This negatively affects plant growth and productivity. 2. Effect on Animals: Birds and insects are also affected by air pollution, influencing their behavior and reproduction. For example, declining bee populations due to air pollution impact the pollination rates of plants. Strategies to Reduce Pollution 1. Public Transportation: Using public transport can help to reduce vehicle emissions. 2. improvement of Energy Efficiency: using Implementing energy-efficient technologies in homes and industries. Example: Using LED bulbs and high-efficiency appliances. 3. Increasing Green Spaces: Planting trees and creating public gardens to help improve air quality. 01063200774 52 ENG / Mahmoud FATHY