General Chemistry and Basic Biology: Key Concepts and Terminology

General Chemistry and Basic Biology Concepts

Chemical Bonds and Atomic Structure

This section covers the types of chemical bonds, atomic structure, and the nature of subatomic particles, which are foundational topics in general chemistry.

• Chemical Bonds: Chemical bonds are forces that hold atoms together in compounds. The main types include:

  • Covalent bonds: Atoms share electron pairs.

  • Ionic bonds: Atoms transfer electrons, resulting in oppositely charged ions that attract each other.

  • Hydrogen bonds: Weak attractions between a hydrogen atom and an electronegative atom (often oxygen or nitrogen).

  • Polar covalent bonds: Electrons are shared unequally between atoms, creating partial charges.

• Weakest Bond: Hydrogen bonds are generally considered the weakest among these types.

• Atomic Mass: The atomic mass of an atom is calculated as the sum of the number of protons and neutrons in its nucleus.

• Subatomic Particles: The three main subatomic particles are:

  • Protons: Positively charged, found in the nucleus.

  • Neutrons: Neutral, found in the nucleus.

  • Electrons: Negatively charged, orbit the nucleus.

• Ions: Atoms or molecules that have gained or lost electrons, resulting in a net charge.

Example: Sodium (Na) loses an electron to become Na+, while chlorine (Cl) gains an electron to become Cl-; they form an ionic bond in NaCl.

Chemical Symbols and Elements

Chemical symbols are one- or two-letter abbreviations for elements. Understanding these is essential for interpreting chemical formulas.

• Na: The symbol for sodium.

• N: Nitrogen

• K: Potassium

• Ni: Nickel

Acids, Bases, and the pH Scale

The pH scale measures the acidity or basicity of a solution. Acids and bases are fundamental concepts in chemistry, affecting many biological and chemical processes.

• Acid: A substance that releases H+ ions in solution.

• Base: A substance that accepts H+ ions or releases OH- ions.

• pH Scale: Ranges from 0 to 14.

  • pH 7: Neutral (pure water)

  • pH < 7: Acidic

  • pH > 7: Basic (alkaline)

Formula:

$\text{pH} = -\log_{10}[\text{H}^+]$

Example: A solution with [H+] = 1 × 10-7 M has a pH of 7 (neutral).

Organic Compounds in Biology

Organic compounds are carbon-based molecules essential for life. The four major classes are:

• Carbohydrates: Provide energy and structural support.

• Lipids: Store energy, form cell membranes.

• Proteins: Serve as enzymes, structural components, and signaling molecules.

• Nucleic Acids: Store and transmit genetic information (DNA and RNA).

Example: Glucose is a carbohydrate; DNA is a nucleic acid.

Water and Ionic Compounds

Water is a polar molecule and an excellent solvent, especially for ionic compounds.

• Solvent Properties: Water can dissolve many ionic compounds by surrounding and separating their ions.

• Hydration Shell: Water molecules form a shell around ions, stabilizing them in solution.

Example: Table salt (NaCl) dissolves in water as Na+ and Cl- ions.

Formation of Compounds

Compounds form when atoms combine through chemical bonds. The main types of bond formation include:

• Ionic Bonds: Formed when atoms gain or lose electrons.

• Covalent Bonds: Formed when atoms share electron pairs.

Biological Molecules and Energy Storage

Carbohydrates such as glycogen are important for energy storage in animals.

• Glycogen: A polysaccharide stored in liver and muscle cells as a backup fuel supply.

• Glucose: The primary energy source for cells.

DNA and Genetic Information

DNA contains genes that code for the production of proteins, which are essential for cellular function.

• Genes: Segments of DNA that provide instructions for making proteins.

Basic Anatomical Terminology (Additional info: for context)

Some questions reference anatomical terms, which are important in biology and health sciences.

• Anterior/Posterior: Front/back of the body.

• Superior/Inferior: Above/below a reference point.

• Medial/Lateral: Toward/away from the midline.

• Proximal/Distal: Closer to/farther from the trunk or point of origin.

• Buccal: Refers to the cheek area.

• Antebrachial: Refers to the forearm.

Table: Types of Chemical Bonds (Comparison)

Bond Type	How Formed	Relative Strength	Example
Covalent	Sharing of electron pairs	Strong	H2O
Ionic	Transfer of electrons	Moderate	NaCl
Hydrogen	Attraction between H and electronegative atom	Weak	Between water molecules

Table: Subatomic Particles

Particle	Charge	Location
Proton	+1	Nucleus
Neutron	0	Nucleus
Electron	-1	Electron cloud/orbitals

Additional info: Some questions reference basic anatomy and biology, which are often included in introductory chemistry courses for health sciences.