Basic Chemistry for Anatomy & Physiology: Study Notes

Basic Chemistry Concepts

Introduction

Chemistry is fundamental to understanding Anatomy & Physiology, as it explains the composition and behavior of matter in the body. This section covers the essential chemical principles relevant to biological systems, including matter, energy, atoms, elements, and chemical bonds.

Matter and Energy

Definitions and Properties

• Matter: Anything that has mass and occupies space. Matter can be seen, smelled, and/or felt. Weight: Mass plus the effects of gravity.

• States of Matter:

  • Solid: Definite shape and volume

  • Liquid: Changeable shape, definite volume

  • Gas: Changeable shape and volume

• Energy: The capacity to do work or put matter into motion. Energy does not have mass or take up space.

• Types of Energy:

  • Kinetic Energy: Energy in action

  • Potential Energy: Stored energy

• Energy can be transformed from potential to kinetic energy; stored energy can be released, resulting in actions.

Forms of Energy

Major Types

• Chemical Energy: Stored in bonds of chemical substances.

• Electrical Energy: Results from movement of charged particles (ions).

• Mechanical Energy: Directly involved in moving matter.

• Radiant/Electromagnetic Energy: Travels in waves (e.g., heat, visible light, ultraviolet light, x-rays).

Energy Conversion: Energy may be converted from one form to another, but some energy is lost as heat (inefficient conversion).

Atoms and Elements

Basic Definitions

• Element: Substances that cannot be broken down into simpler substances by chemical means.

• Atom: Smallest particle of an element with properties of that element.

• Four elements make up 96% of the body: Carbon, Oxygen, Hydrogen, Nitrogen.

• Periodic table lists all known elements (currently 118).

Atomic Structure

• Atoms are composed of three subatomic particles:

  • Protons: Carry a positive charge (+1), mass = 1 atomic mass unit (amu).

  • Neutrons: No charge, mass = 1 amu.

  • Electrons: Carry a negative charge (-1), virtually no mass.

• Electrons orbit the nucleus in shells; the number of protons equals the number of electrons in a neutral atom.

Atomic Number, Mass Number, Isotopes

• Atomic Number: Number of protons in nucleus.

• Mass Number: Total number of protons and neutrons.

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

• Radioisotopes: Unstable isotopes that decompose, releasing energy (radioactivity).

Table: Subatomic Particles

Particle	Charge	Mass (amu)	Location
Proton	+1	1	Nucleus
Neutron	0	1	Nucleus
Electron	-1	~0	Electron Shell

Combining Matter: Molecules and Compounds

Definitions

• Molecule: Two or more atoms bonded together (e.g., O2).

• Compound: Two or more different kinds of atoms bonded together (e.g., C6H12O6, glucose).

Mixtures and Solutions

Types of Mixtures

• Solution: Homogeneous mixture; solute particles do not settle or scatter light.

• Colloid: Larger particles than in a solution; scatter light but do not settle out.

• Suspension: Heterogeneous mixture; visible solutes settle out (e.g., blood).

Solutions: Concentration and Measurement

• Solvent: Substance present in greatest amount (usually water).

• Solute: Substance dissolved in solvent (e.g., glucose in blood).

• Concentration can be expressed as:

  • Percent of solute in total solution

  • Milligrams per deciliter (mg/dL)

  • Molarity (M): Moles of solute per liter of solvent

Avogadro's Number: $6.02 \times 10^{23}$ molecules/mole

Differences Between Mixtures and Compounds

• Mixtures do not involve chemical bonding; compounds do.

• Mixtures can be separated by physical means; compounds by breaking chemical bonds.

• Mixtures can be heterogeneous or homogeneous; compounds are only homogeneous.

Chemical Bonds

Role of Electrons

• Electrons occupy energy levels called electron shells.

• Valence shell: Outermost shell; electrons here are involved in chemical reactions.

• Octet Rule: Atoms strive for 8 electrons in their valence shell (exceptions: H and He want 2).

Types of Chemical Bonds

• Ionic Bonds:

  • Formed when atoms transfer electrons.

  • Creates ions: cations (positive) and anions (negative).

• Covalent Bonds:

  • Formed by sharing electrons between atoms.

  • Single, double, or triple bonds depending on number of shared electrons.

  • Nonpolar covalent bonds: Equal sharing.

  • Polar covalent bonds: Unequal sharing, resulting in partial charges (e.g., H2O).

• Hydrogen Bonds:

  • Attractive force between electropositive hydrogen and an electronegative atom (e.g., oxygen, nitrogen).

  • Important in water and biological molecules.

Summary Table: Types of Chemical Bonds

Bond Type	How Formed	Example
Ionic	Transfer of electrons	NaCl (sodium chloride)
Covalent	Sharing of electrons	H2O (water)
Hydrogen	Attraction between H and electronegative atom	Between water molecules

Additional info:

• Radioisotopes are used in medical imaging and cancer treatment.

• Energy conversions in the body are essential for processes such as muscle contraction and nerve impulse transmission.

• Understanding chemical bonds is crucial for grasping how molecules interact in biological systems.