Chapter 3

Overview of Water and Atoms

  • Water Monomers and Molecules:

    • Water molecules are formed from atoms, which are combinations of different elements.

    • Each atom consists of subatomic particles: protons, neutrons, and electrons.

Subatomic Particles

  • Structure of Atoms:

    • Nucleus: Contains neutrons (neutral charge) and protons (positive charge).

    • Electrons: Negatively charged particles that orbit around the nucleus.

    • The number of protons defines the element; changes in neutron numbers create isotopes.

Elements of Life

  • Essential Elements:

    • The primary elements necessary for life include:

      • Carbon (C)

      • Hydrogen (H)

      • Oxygen (O)

      • Nitrogen (N)

      • Phosphorus (P)

      • Sulfur (S)

    • Remembered through the acronym CHONPS.

    • Each element is the same in terms of subatomic particles but varies in the number of neutrons and protons.

Chemical Bonds

  • Formation of Molecules:

    • Molecules: Formed when atoms are bonded together, often through chemical reactions.

  • Types of Chemical Bonds:

    • Covalent Bonds: Formed when atoms share electrons.

      • Example: Water (H2O) structure involves shared pairs of electrons between hydrogen and oxygen.

    • Polar vs Nonpolar Covalent Bonds:

      • Polar covalent bonds: Unequal sharing of electrons results in a partial charge difference.

      • Nonpolar covalent bonds: Equal sharing of electrons among atoms.

    • Ionic Bonds:

      • Formed by the attraction between oppositely charged ions (cations and anions).

      • Anions: negatively charged ions, Cations: positively charged ions.

  • Hydrogen Bonds:

    • Weaker bonds formed between partially charged molecules, typically involving hydrogen.

    • Examples include attraction between water molecules, making water cohesive and adhesive.

Change in State of Matter

  • Impact of Temperature on Bonds:

    • Heating can break hydrogen bonds, resulting in changes from liquid water to steam.

    • Cooling can strengthen hydrogen bonds, forming ice.

  • Ionic bonds can be easily disrupted by solvents (e.g., water), making ionic compounds soluble.

Functional Groups and Biological Molecules

  • Functional Groups: Specific groups within molecules that provide distinct chemical properties.

    • Common functional groups include amino groups and sulfhydryl groups.

  • Biological Macromolecules: Formed by bonding monomers into polymers through dehydration synthesis:

    • Polymers include carbohydrates, lipids, proteins, and nucleic acids.

Carbohydrates: An Introduction

  • Made primarily of Carbon (C), Hydrogen (H), and Oxygen (O).

    • Monosaccharides: Basic units, e.g., glucose.

    • Disaccharides: Combinations of two monosaccharides, e.g., maltose.

    • Polysaccharides: Long chains of monosaccharides, e.g., starch, glycogen, and cellulose.

Key Processes in Building Biological Structures

  • Dehydration Synthesis:

    • A chemical reaction that links monomers by removing water, forming larger polymers.

  • The significance of each type of biological macromolecule

    • Carbohydrates: Energy storage and structural components of cells.

    • Lipids: Energy storage and membrane structure.

    • Nucleic Acids: Genetic information storage and transfer.

    • Proteins: Enzymatic functions and structural roles.

Conclusion

  • Summary of Key Concepts:

    • Life is fundamentally based on the elements carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur.

    • Understanding of atomic structure is crucial for exploring biological and chemical processes.