Definition of Chemistry
Deals with chemical and physical interactions of matter.
Composed of about 100 different atoms.
Atoms
Basic unit of an element for chemical combinations.
Most atoms originated from the universe's birth.
Composition of Atoms
Nucleus at the center with surrounding electrons.
Nucleus contains protons (positive) and neutrons (neutral).
Electrons (negative) reside outside the nucleus.
Electron Movement
Electrons are much smaller than protons/neutrons and are in constant motion.
Chemical properties depend on the number and arrangement of electrons.
Particle Characteristics
Electrons: mass of 9.10 x 10^-28 grams, charge of -1.602 x 10^-19 coulombs.
Protons determine chemical identity; electrons determine behavior.
Neutrons provide mass and stability.
Atomic Number (Z)
Number of protons in an atom.
Mass Number (A)
Total of protons and neutrons.
Neutral Atoms
Equal number of protons and electrons.
Definition
Same atomic number, different mass numbers (different neutrons).
Examples
Hydrogen isotopes: Protium, Deuterium, Tritium.
Iron isotopes: Iron-56, Iron-55.
Classification
Core electrons: inner electrons.
Valence electrons: outermost electrons, involved in bonding.
Definition of Compounds
Formed when two or more elements combine in definite proportions.
Types of Compounds
Molecular Compounds: Atoms share electrons (e.g., ammonia).
Ionic Compounds: Formed from ions in a 3D network (e.g., sodium chloride).
van der Waals Forces
Weak interactions due to electron movement.
Water Molecules
Polar nature due to charge separation.
Hydrogen Bonds
Attractive interactions between polar molecules.
Cohesion and Adhesion
Cohesion: attraction between same molecules (surface tension).
Adhesion: attraction between different substances.
Heat Capacity
Water can absorb/release energy with minimal temperature change.
Types of Mixtures
Mixtures retain distinct identities; solutions are evenly distributed.
Ionization of Water
Water can ionize into hydroxide (OH-) and hydrogen ions (H+).
pH Scale
Indicates H+ concentration; critical for homeostasis.
Organic Chemistry
Study of carbon-containing compounds.
Macromolecules
Formed via polymerization; four types: carbohydrates, lipids, nucleic acids, proteins.
Carbohydrates
Sugars/starches; energy source and structure.
Lipids
Fats/oils; energy storage and membrane formation.
Nucleic Acids
RNA/DNA; hereditary information storage.
Proteins
Enzymes and structural components; formed from amino acids.
Amino Acids
Building blocks of proteins; variable side chains.
Peptide Bonds
Covalent bonds between amino acids.
Chemical Reactions
Rearrangement of substances; bonds broken and formed.
Chemical Equations
Represent reactions with reactants and products.
Energy Dynamics
Energy is conserved; breaking bonds requires energy, forming bonds releases energy.
Enzymes
Specific catalysts that lower activation energy and enhance reaction rates.