2.1 ELEMENTS OF LIFE

WHAT MAKES AN ORGANISM ALIVE?

  • BIOTIC (LIVING THINGS)

    • Plants

    • Animals

    • Protists

    • Fungus

    • Bacteria

  • ABIOTIC (NON-LIVING THINGS)

    • Water

    • Soil

    • Air

    • Light

    • Minerals



THE 8 CHARACTERISTICS OF LIFE

  1. Organization and the presence of one (unicellular) or more cells (multicellular)

  2. Response to a stimulus (stimuli)

  3. Homeostasis

  4. Metabolism: nutrients

  5. Growth & Development

  6. Reproduction

  7. Change through time

  8. Universal Genetic Code: DNA



MATTER MATTERS

In order for organisms to form, for nutrients to be available, and for biotic and abiotic factors to interact… we need to start with the chemical basics:


CHEMISTRY REVIEW

  • Atomic number: number of protons

  • Element symbol

  • Atomic mass: number of protons plus neutrons averaged over all isotopes

  • Isotopes: forms of an element with a different number of neutrons

  • Electronegativity: the measure of an atom’s ability to attract electrons to itself




BOHR MODEL

  • Show electrons orbiting on shells the nucleus of an atom

  • Each shell is a different energy level and can hold up to a certain number of electrons

    • 1st shell: 2 e-

    • 2nd shell: 8 e-

    • 3rd shell: 8e-



LEWIS DOT MODEL

  • Simplified Bohr diagrams

  • Does not show energy levels

  • Only shows electrons in the valence shell (outermost shell)

  • Electrons are placed around the element symbol



THE THREE TYPES OF BONDS

  1. COVALENT BONDS

    1. Sharing of electrons by two atoms to form molecules and compounds

      1. NON-POLAR COVALENT

        1. Electrons are shared equally between two atoms

      2. POLAR COVALENT

        1. Electrons are not shared equally between two atoms, resulting in partial charges



  1. IONIC BONDS

    1. Transfer of electrons from one atom to another atom forms ionic compounds and salts

    2. The attraction between the anion and cation forms the ionic bond

      1. CATION

        1. positively charged ion

      2. ANION

        1. negatively charged ion



  1. HYDROGEN BONDS

    1. Intermolecular bonds forms between molecules

      1. When a hydrogen atom is bonded to an electronegative atom (usually O, N, or F) the electrons are not being shared equally. Causing hydrogen to be partial positive charge

        1. The H bonds form & break frequently due to movement