bio ch 2: Atomic Chemistry

Chapter 2: Atomic Chemistry

Introduction

  • Discussion of background noise due to roof renovations, which are a decision made by the Homeowners' Association (HOA).

Importance of Chemistry in Biology

  • Biotechnology: A nine-letter word that is fundamentally linked to chemistry.

  • Pharmacology and Biology: Both disciplines depend on chemistry.

  • Biochemistry: The study of the chemical processes within and relating to living organisms, emphasizing the chemical nature of life.

Atoms and Their Components

  • Atoms: Defined as the basic units of matter.

  • Electron: A significant part of the atom involved in bonding.

    • Importance: Electrons facilitate the joining of atoms into larger structures, forming molecules.

  • Covalent Bonding: One way atoms are joined, resulting in larger structures called molecules.

    • Covalent Bonds: Strong bonds essential in the formation of biomolecules.

Types of Bonds in Biology

  • Noncovalent Bonds: Weaker interactions compared to covalent bonds but crucial in biological processes.

  • Summary of bonding types:

    • Covalent Bonds: Strong.

    • Noncovalent Bonds: Weaker but important.

Molecular Shape and Function

  • Concept: Form begets function; the shape of biomolecules determines their function.

  • Importance in biology: Biomolecules' functions depend on their shapes.

  • Discussion of how molecular shape is determined.

Chemical Reactions and Biomolecules

  • Chemical Reactions: Essential for creating and building biomolecules, thus requiring a thorough understanding of chemistry.

Elements and Their Importance

The Periodic Table

  • Elements: Fundamental types of matter in the environment, cannot be broken down chemically.

  • Natural Occurrence: 92 elements occur naturally, while others are artificially created.

  • Essential Elements for Life: The number varies by organism:

    • Complex Organisms: Require 25 essential elements.

    • Simpler Organisms: Can survive with as few as 17 elements.

Major Elements in Living Matter

  • 96% of living matter by weight is composed of just four elements:

    • Hydrogen (H)

    • Carbon (C)

    • Nitrogen (N)

    • Oxygen (O)

    • Known as CHON for memorization.

  • The remaining 4% consists of seven additional elements:

    • Sodium (Na)

    • Magnesium (Mg)

    • Calcium (Ca)

    • Potassium (K)

    • Phosphorus (P)

    • Sulfur (S)

    • Chlorine (Cl)

  • The total for essential elements: 25 (4 major + 7 others = 11, leaving 14 essential trace elements).

Trace Elements

  • Definition: Elements required in minute quantities; they make up the remaining 14.

  • Example: Iodine - essential for thyroid function, and its deficiency can lead to goiter.

Atomic Structure

  • Definition of an Atom: The smallest unit of an element, retaining the properties of that element.

Subatomic Particles

  • Components of an Atom:

    • Proton: Positive charge, located in the nucleus.

    • Neutron: Neutral charge, also in the nucleus.

    • Electron: Negative charge, orbiting the nucleus.

Atomic Models

  • Misconception about electron movement:

    • Incorrect: Electrons move like planets orbiting the sun.

    • Correct: Electrons exist in an electron cloud, occupying different distances from the nucleus.

Atomic Representation

  • Element Symbols: Represented by one or two-letter symbols; atomic number typically displayed as a subscript.

  • Atomic Number: The number of protons in an atom defining the element.

  • Example: Hydrogen: Atomic Number 1, has 1 proton and 1 electron.

  • Helium: Atomic Number 2, has 2 protons, 2 electrons, and 2 neutrons.

Mass and Weight of Atoms

  • Majority of atomic mass derives from protons and neutrons, each weighing approximately 1.7imes10−24extgrams1.7 imes 10^{-24} ext{ grams} .

  • Dalton (Da): A unit of mass convenient for describing atomic and molecular weights. 1 Dalton is the mass of one proton or neutron.

  • Comparative Scale: Grams (large unit) vs. Dalton (small unit).

Atomic Weights

  • Hydrogen: Approximately 1 Dalton.

    • Justification: It has 1 proton, and the electron's weight is negligible.

  • Helium: Atomic Weight of about 4 Daltons (2 protons + 2 neutrons).

  • Mass Number: Defined as the total number of protons and neutrons.

    • Example: Helium's mass number = 4, represented as a superscript before the element's symbol.

Carbon Characteristics

  • Carbon: Atomic Number 6, Atomic Weight approximately 12.

  • Neutral carbon has:

    • 6 protons

    • 6 electrons

    • Varied number of neutrons (6, 7, or 8).

  • Isotopes of Carbon:

    • Carbon-12 (C-12): 6 Neutrons, most abundant.

    • Carbon-13 (C-13): 7 Neutrons, about 1% presence.

    • Carbon-14 (C-14): 8 Neutrons, less than 1%, unstable.

  • Defining Isotopes: Variations of an element with differing neutrons.

  • Stability: Most isotopes are stable; C-14 is an exception that decays.

Isotope Behavior and Decay

  • Radioactive Decay: Process where unstable isotopes like C-14 release energy as a neutron converts into a proton and an electron.