Introduction to chemistry

Introduction to Chemistry in Biology

  • Importance of Chemistry in Understanding Living Organisms

    • Chemical reactions are essential for physiological processes.

    • Bonding is fundamental for forming larger structures from smaller components.

    • Examples of hierarchy in biological organization:

    • Atoms → Molecules → Macromolecules → Organelles → Cells → Tissues → Organs

    • Highly organized nature of living organisms emphasizes the significance of bonding and reactions.

Bonding and Reactions

  • Importance of Bonding

    • Atoms interact to form molecules through bonding.

    • These molecular structures enable the formation of larger biological components like cells and tissues.

  • Chemical Reactions

    • Breakdown of substances to release energy (catabolic) and the construction of large molecules (anabolic) requires energy input.

    • Metabolism encompasses both types of reactions.

    • General chemistry will focus on atomic structure rather than detailed balancing equations.

Atomic Structure Fundamentals

  • Atoms as Stable Structures

    • Atoms are the most stable unit; they are foundational for all living organisms.

  • Hierarchy of Complexity

    • Understanding of atoms and their interactions is crucial for comprehending physiological processes.

  • Types of Subatomic Particles

    • Nucleus: Contains protons and neutrons.

    • Protons: Positively charged particles.

    • Neutrons: Neutral particles with no charge, contribute to mass.

    • Electrons: Negatively charged particles that orbit the nucleus, involved in bonding.

Periodic Table and Atom Information

  • Use of the Periodic Table

    • The periodic table provides vital information for chemical elements:

    • Element names, symbols, and atomic numbers.

    • Atomic number indicates the number of protons in the nucleus.

      • Example: Hydrogen (H) has an atomic number of 1, indicating one proton and one electron.

    • Atomic mass indicates the total weight of protons and neutrons and calculates the number of neutrons.

  • Calculation of Neutrons

    • Atomic mass = Number of Protons + Number of Neutrons

    • For hydrogen (mass = 1.008):

    • Protons = 1, Neutrons = 0 (since atomic mass is approximately 1).

The Octet Rule

  • Definition of the Octet Rule

    • Atoms gain, lose, or share electrons to fill their outermost electron shell, aiming for stability.

  • Shell Capacity

    • First shell: Holds a maximum of 2 electrons.

    • Second shell and subsequent shells: Hold a maximum of 8 electrons.

  • Importance of Valence Electrons

    • Electrons in the outermost shell (valence electrons) determine how atoms interact chemically.

    • Atoms with unfilled valence shells are unstable and will participate in chemical bonding to achieve stability.

Isotopes and Their Clinical Relevance

  • Definition of Isotopes

    • Atoms of the same element can have different numbers of neutrons, leading to variations in mass but similar chemical properties.

    • Example:

    • Hydrogen-1: 1 proton, 0 neutrons.

    • Hydrogen-2: 1 proton, 1 neutron.

    • Hydrogen-3: 1 proton, 2 neutrons.

  • Applications of Radioisotopes

    • Used in medical technology such as PET scans and X-rays due to their unstable nature and radiation emission.

Drawing and Understanding Atomic Structures

  • Example Atom: Carbon

    • Atomic Number: 6 ; Atomic Mass: 12

    • Protons: 6

    • Electrons: 6

    • Neutrons: 6 (12 - 6 = 6)

  • Example Atom: Sodium

    • Atomic Number: 11 ; Atomic Mass: 23

    • Protons: 11

    • Electrons: 11

    • Neutrons: 12 (23 - 11 = 12)

Definitions of Ions

  • Definition of Ions

    • Charged particles that result from an unequal number of protons and electrons.

    • Ions can be:

    • Anions: Negatively charged ions, formed by gaining electrons (more electrons than protons).

    • Cations: Positively charged ions, formed by losing electrons (more protons than electrons).

Ionization Process and Examples

  • Ionization

    • The process of transferring electrons from one atom to another to achieve stability, leading to the formation of ions.

  • Example of Sodium and Chlorine Ionization

    • Sodium (11 protons, 11 electrons): loses one electron → becomes a cation (Na+).

    • Chlorine (17 protons, 17 electrons): gains one electron → becomes an anion (Cl-).

    • Resultant charge states:

    • Na+: 11 protons, 10 electrons = positive charge.

    • Cl-: 17 protons, 18 electrons = negative charge.

Summary of Elements

  • Definition of Elements

    • Substances that consist of only one type of atom.

    • Principal elements (abundant) vs. trace elements (less abundant).

  • Chart of Principal and Trace Elements

    • Include abundant elements such as Carbon, Oxygen, and Hydrogen, and a list of trace elements for reference.