macroeconomics

Introduction

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Key Concepts

Elements of Life

• Definition: Elements are pure substances that cannot be broken down into simpler substances.

• Essential Elements: Oxygen, carbon, hydrogen, nitrogen are essential for life.

• Trace Elements: Include iron, iodine, and copper, which are required in small amounts.

Structure of Atoms

• Attractive Forces: Atoms are the prime building blocks of matter.

• Subatomic Particles:

  • Protons: Positive charge (+)

  • Neutrons: No charge

  • Electrons: Negative charge (-)

• Isotopes: Atoms with the same number of protons but different numbers of neutrons.

Chemical Bonds

• Definition: Compounds consist of two or more elements tied together by chemical bonds.

• Types of Bonds:

  • Ionic Bonds: Formed when electrons are transferred, resulting in charged ions.

  • Covalent Bonds: Formed when electrons are shared; can be polar or non-polar based on electron sharing.

Properties of Water

• Hydrogen Bonds: Weak attractions between molecules influenced by the electrical polarity of water molecules.

  • Cohesion: Water molecules stick together, contributing to surface tension.

  • Adhesion: Water molecules adhere to other substances.

• Capillary Action: Combination of cohesion and adhesion that assists water movement in plant systems.

• Surface Tension: The strong cohesive forces allow some objects to float on the surface of water.

Conclusion

• Understanding the structure of atoms, chemical bonds, and properties of water is fundamental in the study of biological systems.