1103 1-3 Atoms & Molecules
Page 1: Introduction to Atoms & Molecules
Course: Biology 1103
Topic Focus: Understanding of atoms and molecules as fundamental elements of life.
Page 2: Objectives
Chemical Element: Substance that cannot be broken down into simpler substances.
Common elements in the human body:
Oxygen (O): Essential for cellular respiration.
Carbon (C): Backbone of organic molecules, forming complex structures.
Hydrogen (H): Integral in water and organic compounds.
Nitrogen (N): Key component of amino acids and nucleic acids.
Atom: Smallest unit of an element that retains its properties.
Structure: Composed of protons (+), neutrons (0), and electrons (-).
Molecule: Two or more atoms bonded together.
Compound: Molecule composed of two or more different elements.
Ions: Formed through loss/gain of electrons, creating positively charged cations or negatively charged anions.
Covalent Bonds: Formed by sharing electrons between atoms.
Organic vs Inorganic Molecules:
Organic: Contain carbon and typically hydrogen.
Inorganic: Generally do not contain both, e.g., water, salts.
Characteristics of Organic Molecules:
Useful in living organisms due to metabolism energy release and complexity.
Examples: Carbohydrates, proteins, lipids, nucleic acids.
Page 3: Matter & Elements
Matter: Composed of elements in pure form and various combinations.
Element Definition: Cannot be chemically broken down further.
Page 4: Structure of an Atom
Subatomic Particles:
Nucleus: Houses protons (+) and neutrons (0).
Electron Shell: Contains electrons (-).
Atomic Models: Helium (He) simplifies atomic structure understanding.
Page 5: Elements in Detail
Element Information:
Includes common elements and their atomic properties.
Atomic symbol, atomic mass, and atomic number which equate to the number of protons and typically electrons.
Page 6: Isotopes
Isotopes Variations: Atoms differing by neutrons but identical in electrons and protons.
Behavior in reactions is similar regardless of isotopes.
Page 7: Chemical Behavior of Atoms
Chemical Behavior: Determined primarily by electron distribution in shells.
Valence Shell Importance: Incomplete shells lead to reactivity; complete shells (octet rule) yield stability.
Page 8: Valence Shells & Chemical Bonding
Valence Shells: Incomplete shells lead to bond formation through electron sharing (covalent) or gaining/loss (ionic).
Page 9: Molecules vs Compounds
Molecules: Two or more atoms.
Compounds: Molecule that includes at least two different elements.
Examples: N2, O2 as pure molecules vs. H2O as a compound.
Page 10: Ionic Bonds
Ionic Bonds: Formed when atoms lose or gain electrons, changing their charge and forming ions.
Example: Sodium (Na) loses an electron to chlorine (Cl) forming Na+ (cation) and Cl- (anion).
Page 11: Ionic Bonds Continuation
Ion Properties: Describe the charge changes and how opposite charges attract to form ionic bonds.
Page 12: Covalent Bonds
Covalent Bonds: Electrons shared between atoms.
Strongest type of bond, requiring energy to break.
Example: Molecular oxygen (O2).
Page 13: Polar and Nonpolar Covalent Bonds
Bond Types: Nonpolar bonds share electrons equally; while polar bonds share them unequally, leading to partial charges.
Page 14: Organic vs Inorganic Molecules
Organic Molecules: Always contain carbon and usually involve C-H bonds, complex structures, and release energy for metabolic activities (e.g., fats, sugars, proteins).
Inorganic Molecules: Generally simpler, lack C-H bonds (e.g., H2O, NaCl).
Page 15: Biological Importance of Water
Objectives: Understanding water's role in biological systems, its proportion in body weight, and distribution across tissues.
Page 16: Structure of Water
Molecule Composition: 2 hydrogen atoms bonded to one oxygen atom via polar covalent bonds, imparting polarity.
Page 17: Hydrogen Bonds in Water
Bonding Mechanics: Water molecules are held together through hydrogen bonds formed due to polarity.
Page 18: Water's Biological Importance
Cushing and Lubrication: Water serves as a lubricant and cushion (e.g., in joints).
Heat Sink: Acts to moderate temperature, absorbing heat with minimal temperature change, aiding evaporative cooling.
Page 19: Solvent Versatility of Water
Solvent Properties: Polarity makes water an excellent solvent.
Hydrophilic substances dissolve easily (e.g., sugars, salts).
Hydrophobic substances do not (e.g., lipids).
Amphipathic: Substances like phospholipids have hydrophilic and hydrophobic properties.
Page 20: Water Reactivity
Chemical Reactivity: Participates in biochemical reactions, such as dehydration synthesis and hydrolysis.
Page 21: Distribution of Body Water
Body weight percentages of water vary, with most body fluids being affected by age and body type.
Infants: 75-80%, Males: 60%, Females: 55%, Seniors: as low as 45%.
Page 22: Water Content Across Organs
Organ Water Contents: Brain (80-85%), Blood (80%), Heart (75-80%), Skin (70-75%), etc.
Page 23: Biochemistry Objectives
Goals include understanding carbon chemistry, carbohydrate structure/function, lipid roles, protein functions, and nucleic acid roles.
Page 24: Carbon & Organic Compounds
Carbon's Importance: Forms diverse structures due to its tetravalent nature and ability to form covalent bonds.
Page 25: Four Major Biological Macromolecules
Essential macromolecules include carbohydrates, lipids, proteins, and nucleotides pertinent to human functions.
Page 26: Macromolecules Overview
Composition: Comprised of smaller units (monomers).
Polymers formed via dehydration synthesis.
Page 27: Functional Groups
Definition: Chemical groups that participate in reactions, providing consistent behavior across organic molecules.
Page 28: Carbohydrates
Molecule Components: Composed of C, H, O; include simple and complex sugar forms (monosaccharides and polysaccharides).
Common