Chemistry of Life

  • Definition of Biology:

    • Biology is the study of life, focusing on the shared characteristics of living organisms.

    • All living things rely heavily on principles of chemistry.

Characteristics of Life

  • Living organisms share several common characteristics, including:

    • Cellular Organization

    • Homeostasis

    • Requires & Converts Energy

    • Growth & Development

    • Response to Environment

    • Ability to Adapt / Evolve

    • Reproduce / Pass on Genetic Information

Cellular Organization

  • Hierarchical structure of life:

    • Atom

    • Molecule

    • Macromolecule

    • Organelle

    • Cell

    • Tissue

    • Organ

    • Organ System

    • Organism

Matter and Its Composition

  • Definition of Matter:

    • Anything that occupies space and has mass.

    • Matter is measurable.

  • Elements:

    • Composition of matter is described in terms of elements, which are “pure” substances that cannot be broken down by chemical reactions.

    • Elements consist of only ONE type of atom.

Abundance of Elements

  • Natural Elements:

    • There are 92 naturally occurring elements, with approximately 26 synthesized in laboratories.

  • Each element has a unique symbol and a Latin or German name.

Essential Elements for Life

  • Approximately 20-25% of natural elements are necessary for life.

  • Four primary elements that make up 96% of living matter:

    • Oxygen (O)

    • Carbon (C)

    • Hydrogen (H)

    • Nitrogen (N)

  • Secondary elements that make up the remaining 4%:

    • Calcium (Ca)

    • Phosphorus (P)

    • Potassium (K)

    • Sodium (Na)

    • Sulfur (S)

    • Chlorine (Cl)

    • Magnesium (Mg)

Atomic Structure

  • Atoms:

    • Definition: The smallest unit of matter that retains the properties of an element.

    • Atoms are composed of subatomic particles:

      • Protons (+)

      • Neutrons (0)

      • Electrons (-)

Nucleus of the Atom

  • Protons:

    • Positively charged particles with a weight of 1 atomic mass unit (amu).

  • Neutrons:

    • Neutral particles with a weight of 1 amu.

Electron Configuration

  • Outer Shell / Cloud of Atom:

    • Electrons:

      • Negatively charged particles located in orbitals around the nucleus.

    • Orbital Capacity:

      • 1st shell = 2 electrons

      • 2nd shell = 8 electrons

      • 3rd shell = 18 electrons

Identifying Atoms

  • Atoms are differentiated by the number and arrangement of subatomic particles.

  • Example:

    • Fluorine: Atomic Number 9, Mass Number 19

    • Neon: Atomic Number 10, Mass Number 20

    • Sodium: Atomic Number 11, Mass Number 23

    • Magnesium: Atomic Number 12, Mass Number 24

Role of Protons and Electrons

  • Protons:

    • Determine the identity of the element.

  • Electrons:

    • Govern the atom's personality and chemistry.

Key Atomic Concepts

  • Atomic Number (Z):

    • The number of protons in the nucleus.

  • Mass Number:

    • The sum of protons and neutrons.

  • Atomic Mass:

    • The approximate weight of the nucleus, expressed in daltons (amu).

    • Electrons have negligible weight.

Isotopes

  • Some atoms can fluctuate in weight due to variations in the number of neutrons, resulting in isotopes.

  • Isotope Characteristics:

    • Different isotopes of the same element behave differently in chemical reactions.

Carbon Isotopes

  • Carbon has three natural isotopes:

    • Carbon-12: 98.9% abundance, 6 protons, 6 neutrons.

    • Carbon-13: 1.1% abundance, 6 protons, 7 neutrons.

    • Carbon-14: <0.1% abundance, 6 protons, 8 neutrons.

    • The proton number remains consistent while the neutron number varies.

Determining Atomic Behavior

  • The behavior of an atom is largely dependent on the number and arrangement of its electrons, which occupy orbitals around the nucleus.

  • Orbital Characteristics:

    • Each orbital is located at a certain distance from the nucleus and has a particular shape that influences energy levels and stability.

Electron Shell Stability

  • Electrons prefer stability in lower-energy orbitals. Electrons fill inner orbitals before moving to outer orbitals.

  • Electrons may move between orbitals when their energy levels change.

Valence Electrons and Bonding

  • Valence Orbital / Shell:

    • The outermost electrons of an atom, crucial for chemical reactions and bonding.

    • Valence electrons interact to form chemical bonds.

Bonding Characteristics

  • Atoms tend to bond to achieve a full outer shell, aiming for stability through bonding.

  • Goal of Chemical Reactions:

    • Achieve stability by completing the valence shell through reactions with other atoms.