A&P CH2 PART A

Chapter Overview

• Purpose of the chapter:

  • Introduce the language and concepts of chemistry

  • Discuss organization of matter

  • Explain formation of chemical bonds and reactions

  • Compare organic and inorganic compounds

Introduction

• Chemicals compose the body and are integral to all body activities.

Basic Principles of Chemistry

• Chemistry: Study of structure and interactions of matter.

• Matter: Anything with mass and occupies space.

  • Mass: Amount of matter (constant).

  • Weight: Force of gravity acting on mass (varies).

How Matter is Organized

• Forms of Matter:

  • Solid: Definite shape and volume (e.g., bones).

  • Liquid: Definite volume, assumes container shape (e.g., blood plasma).

  • Gas: No definite shape or volume (e.g., oxygen, carbon dioxide).

Chemical Elements

• Composed of substances that cannot be broken down chemically.

• Common elements:

  • O = Oxygen

  • C = Carbon

  • H = Hydrogen

  • N = Nitrogen

• Trace elements include Aluminum (Al), Copper (Cu), and others.

Atoms

• Atoms: Smallest units retaining element properties.

• Composed of:

  • Protons: Positively charged, found in nucleus.

  • Neutrons: Neutral, also in nucleus.

  • Electrons: Negatively charged, orbiting nucleus.

Atomic Structure

• Atoms consist of a nucleus (protons and neutrons) and electron cloud.

• Electrons reside in shells around the nucleus:

  • 1st shell: 2 electrons

  • 2nd shell: 8 electrons

  • 3rd shell: 18 electrons

Atomic Number and Mass Number

• Atomic Number: Number of protons (equals number of electrons in a neutral atom).

• Mass Number: Sum of protons and neutrons in nucleus.

Isotopes

• Variants of an element with same protons, different neutrons.

• Stable isotopes: Do not change over time.

• Radioactive isotopes: Unstable, decay over time (useful in studying tissues).

Atomic Mass

• Dalton (amu): Unit for atomic mass.

• Comparison of masses:

  • Neutron: 1.008 daltons

  • Proton: 1.007 daltons

  • Electron: 0.0005 daltons

• Atomic mass reflects relative abundance of isotopes.

Ions, Molecules, and Compounds

• Ion: Charged atom (e.g., Ca2+).

• Ionization: Gain/loss of electrons.

• Molecule: Combination of two or more atoms sharing electrons.

• Compound: Substance with two or more different elements.

Clinical Connections

• Free radicals: Charged atoms/groups with unpaired electrons, linked to diseases.

• Antioxidants: Inactivate free radicals.