Fundamental Chemistry Concepts for Anatomy & Physiology

Atoms and Atomic Structure

Definition and Components of the Atom

The atom is the smallest unit of matter that cannot be broken down further by chemical means. Understanding atomic structure is essential for grasping the chemical basis of physiological processes.

• Nucleus:

  • Contains protons (positively charged) and neutrons (neutral).

  • Responsible for most of the atom's mass.

• Electron Cloud:

  • Contains electrons (negatively charged).

  • Electrons have almost no mass compared to protons and neutrons.

Subatomic Particle	Mass (kg)	Charge		Mass	Charge
Electron (e-)	9.11 × 10-31	-1.6 × 10-19	0	-1
Proton (p+)	1.67 × 10-27	1.6 × 10-19	1	+1
Neutron (n)	1.67 × 10-27	0	1	0

The Periodic Table

Organization and Groups

The periodic table arranges elements by increasing atomic number and groups elements with similar chemical properties together.

• Period: Horizontal rows; the period number indicates the number of electron shells.

• Group: Vertical columns; the group number tells the number of valence electrons for main group elements.

• Classification: Elements are classified as metals, metalloids, and nonmetals.

Type	Properties
Metals	Good conductors, malleable, shiny
Nonmetals	Poor conductors, brittle, dull
Metalloids	Intermediate properties

Atomic Number, Mass Number, and Isotopes

Definitions and Calculations

Atomic number and mass number are fundamental for identifying elements and their isotopes.

• Atomic Number (Z): Number of protons in an atom.

• Mass Number (A): Number of protons plus neutrons.

• Isotopes: Atoms of the same element with different numbers of neutrons.

• Atomic Mass: Weighted average of all isotopes.

Example: Carbon isotopes:

• $^{12}C$: 6 protons, 6 neutrons

• $^{13}C$: 6 protons, 7 neutrons

• $^{14}C$: 6 protons, 8 neutrons

Mole Concept

Definition and Application

The mole is a standard unit for counting atoms and molecules in chemistry.

• Avogadro's Number: $6.022 \times 10^{23}$ units per mole.

• Mole: Number of atoms or molecules in a sample.

Example: If you have a dozen eggs, you have 12 eggs. If you have a mole of atoms, you have $6.022 \times 10^{23}$ atoms.

Major Elements in the Human Body

Essential Elements and Trace Elements

Certain elements are vital for life and are found in large amounts in living organisms.

• Major elements: C, H, O, N, P, S, Ca, K, Na, Cl, Mg

• Trace elements: Required in small amounts for proper physiological function.

Element	Biological Significance
Calcium (Ca)	Important for blood clotting, muscle contraction, nerve function
Sodium (Na)	Regulates fluid balance, nerve and muscle function
Magnesium (Mg)	Enzyme cofactor, muscle and nerve function
Iron (Fe)	Essential for oxygen transport (hemoglobin)
Trace elements (e.g., Iodine, Zinc)	Required for enzyme function, hormone production

Chemical Bonds

Ionic, Covalent, and Hydrogen Bonds

Chemical bonds are forces that hold atoms together in molecules and compounds.

• Ionic Bonds: Electrostatic force between oppositely charged ions formed by transfer of electrons.

  • Cation: Positive ion (e.g., Na+)

  • Anion: Negative ion (e.g., Cl-)

  • Example: NaCl = Na+ + Cl-

• Covalent Bonds: Sharing of electrons between atoms.

  • Equal sharing: Nonpolar (hydrophobic), e.g., H2

  • Unequal sharing: Polar (hydrophilic), e.g., H2O

• Hydrogen Bonds: Weak electrostatic attraction between polar molecules, especially when hydrogen is bonded to nitrogen, oxygen, or fluorine.

Water: Properties and Importance

Physical and Chemical Properties

Water is essential for life and has unique properties due to its molecular structure and hydrogen bonding.

• High boiling point

• Low vapor pressure

• High temperature of vaporization

• Makes up approximately 2/3 of body weight

Example: Hydrogen bonding keeps water molecules "stuck together," contributing to its high boiling point.

Solutions, Solvents, and Solutes

Definitions and Examples

Solutions are homogeneous mixtures of two or more substances.

• Solvent: Substance that dissolves another substance.

• Solute: Substance being dissolved.

• Solution: Solvent containing the solute.

Acids, Bases, and pH

Definitions and pH Scale

Acids and bases are substances that alter the concentration of hydrogen ions (H+) in solution. The pH scale measures the acidity or basicity of a solution.

• Acid: Gives off H+ in water (e.g., HCl → H+ + Cl-).

• Base: Gives off OH- in water (e.g., NaOH → Na+ + OH-).

• Strong Acid/Base: Complete dissociation in water.

• Weak Acid/Base: Incomplete dissociation in water.

pH Calculation:

• $\text{pH} = -\log [H^+]$

• pH 7 is neutral; pH < 7 is acidic; pH > 7 is basic.

[H+]	pH
1.0 × 10-1	1
1.0 × 10-2	2
1.0 × 10-3	3
1.0 × 10-4	4
1.0 × 10-5	5
1.0 × 10-6	6
1.0 × 10-7	7
1.0 × 10-8	8
1.0 × 10-9	9
1.0 × 10-10	10
1.0 × 10-11	11
1.0 × 10-12	12
1.0 × 10-13	13
1.0 × 10-14	14

Buffers and Homeostasis

Role of Buffers in pH Regulation

Buffers help maintain stable pH in biological systems by minimizing changes in hydrogen ion concentration.

• Composed of a weak acid and its corresponding weak base.

• Example: $\text{H}_2\text{O} + \text{CO}_2 \rightarrow \text{H}_2\text{CO}_3$ (carbonic acid) $\rightarrow \text{HCO}_3^-$ (bicarbonate) $+$ H+

• Plays a critical role in homeostasis, especially in blood pH regulation.

Additional info:

• Some context and explanations have been expanded for clarity and completeness.

• Tables have been recreated and summarized for study purposes.