Fundamentals of Matter and Atomic Structure in Anatomy & Physiology

Objectives

• Define chemical element and list the four elements that form the bulk of body matter.

• List the subatomic particles and describe their relative masses, charges, and positions in the atom.

• Draw the atomic structure of any given atom.

• Define atomic number, atomic mass, isotope, and radioisotope.

• Explain the role of electrons in chemical bonding and in relation to the octet rule.

• Name and describe four types of chemical bonds: ionic, polar covalent, nonpolar covalent, and hydrogen bonds.

• Distinguish between organic and inorganic compounds.

• Differentiate between acids, bases, and salts.

• Explain the importance of water to body homeostasis and provide several examples of the role water plays in the human body.

• Explain the concept of pH and state the pH of blood.

Matter

A. Definition and Properties of Matter

Matter is anything that occupies space and has mass. In anatomy and physiology, understanding matter is essential because all living and non-living things are composed of matter.

• Physical "stuff" of the universe: Includes solids, liquids, and gases.

• States of matter: Can exist as a solid, liquid, or gas.

• Weight: The measure of the amount of substance by mass, influenced by gravity. On Earth, mass and weight are often used interchangeably, but technically, weight is mass under the influence of gravity.

B. Composition of Matter

1. Elements

Elements are the fundamental units of matter. They cannot be broken down into simpler substances by ordinary chemical means.

• Definition: Pure substances consisting of only one type of atom.

• Major elements in the body: 96% of the human body is made up of four elements: Hydrogen (H), Oxygen (O), Nitrogen (N), and Carbon (C).

• Minor elements: Other elements are present in smaller amounts and are essential for life (e.g., calcium, potassium).

2. Atoms

Atoms are the smallest units of an element that retain the properties of that element. They are the building blocks of matter.

• Atomic Structure:

  • Nucleus: Central part of the atom containing protons and neutrons.

  • Protons (p+): Positively charged particles found in the nucleus.

  • Neutrons (n0): Neutral particles found in the nucleus.

  • Electrons (e-): Negatively charged particles that orbit the nucleus in electron shells.

• Outside of nucleus: Electrons are arranged in energy levels or shells around the nucleus.

Key Terms and Concepts

• Atomic Number: The number of protons in the nucleus of an atom. Determines the element's identity.

• Atomic Mass: The sum of protons and neutrons in the nucleus. Equation: $\text{Atomic Mass} = \text{Number of Protons} + \text{Number of Neutrons}$

• Isotope: Atoms of the same element with different numbers of neutrons, and thus different atomic masses.

• Radioisotope: An isotope that is unstable and emits radiation as it decays.

Example: Atomic Structure of Carbon

• Carbon (C): Atomic number 6 (6 protons), usually 6 neutrons, 6 electrons.

• Isotopes: Carbon-12, Carbon-13, Carbon-14 (used in radiometric dating).

Table: Subatomic Particles

Particle	Charge	Location	Relative Mass
Proton (p+)	+1	Nucleus	1
Neutron (n0)	0	Nucleus	1
Electron (e-)	-1	Electron shells	~1/1836

Additional info:

• Understanding atomic structure is foundational for topics such as chemical bonding, molecular interactions, and physiological processes in the human body.

• Further study will include chemical bonds, water properties, acids and bases, and pH—all crucial for anatomy and physiology.