Lesson 2.1: CHEMISTRY OF LIFE


MATTER AND ITS CLASSIFICATIONS

  • Definition: Matter is anything that takes up space and has mass.

  • Examples: Rocks, metals, oils, gases, and living organisms.

ELEMENTS OF LIFE

  • Essential Elements: 20–25% of the 92 natural elements are essential for life.

    • Humans: Need 25 elements.

    • Plants: Require 17 elements.

TRACE ELEMENTS

  • Required by organisms in minute quantities.

  • Examples:

    • Iron (Fe): Needed by all life.

    • Iodine (I): Essential for thyroid hormone in vertebrates.

ELEMENTS IN LIVING SYSTEMS AND THEIR FUNCTIONS

  • C (Carbon): Main component of organic compounds.

  • H (Hydrogen): Major fuel source for energy production.

  • O (Oxygen): Essential for water molecules and organic compounds.

  • N (Nitrogen): Key element in proteins.

  • P (Phosphorus): Major component of nucleic acids and energy-rich compounds.

  • S (Sulfur): Part of some amino acids and vitamins.

  • Ca (Calcium): Major component of bones and biological signals in the body.

SUBATOMIC PARTICLES

  • Definition: Protons and electrons are charged while neutrons are neutral.

  • Operation: Protons and neutrons are located in the atomic nucleus; electrons form a cloud around the nucleus due to charge attraction.

VALENCE ELECTRONS

  • Valence: Electrons that determine an atom’s chemical properties.

  • Definition: Electrons in the outer shells that are not filled.

INTRAMOLECULAR FORCES

  • Relevant for understanding bonds within molecules.

IONIC BOND

  • Formed when one atom strips an electron from another due to unequal attraction.

  • Results: Formation of cations (positive ions) and anions (negative ions) which attract each other.

COVALENT BOND

  • Formed from shared pairs of valence electrons between two nonmetals.

  • Types:

    • Single Bond: 1 pair of electrons shared.

    • Double Bond: 2 pairs of electrons shared.

    • Triple Bond: 3 pairs of electrons shared.

POLAR VS NON-POLAR

  • Electronegativity: Measure of an atom’s attraction for electrons in a bond.

  • Polar Molecules: Unequal electron distribution leading to dipoles.

  • Nonpolar Molecules: Equal distribution or cancellation of dipoles.

INTERMOLECULAR FORCES

  • Forces that occur between molecules, significant for chemical properties.

HYDROGEN BONDING

  • A weak bond between a covalently bonded hydrogen atom and an electronegative atom (O, N, F).

  • Contributes to the unique properties of water and biomolecules.

CHEMICAL REACTIONS

  • Definition: Involves making and breaking of chemical bonds.

  • Example: Reaction between hydrogen and oxygen to form water.

  • Reactants and Products: Reactants turn into products during a reaction, measured by coefficients in chemical equations.

LAW OF CONSERVATION OF MASS

  • Matter cannot be created or destroyed, only transformed.

  • Total mass remains constant during any physical or chemical process.

  • Example: Photosynthesis rearranges matter in green plants.