Chemistry of Life: Atomic Structure and Elements

Introduction

The chemistry of life is foundational to understanding biological processes. This study guide reviews atomic structure, the periodic table, and the basic chemical principles essential for biology students.

Periodic Table of Elements

Understanding Atomic Structure

Atoms are the smallest units of matter that retain the properties of an element. Each atom consists of subatomic particles: protons, neutrons, and electrons.

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

• Atomic Weight (Mass Number): The sum of protons and neutrons in the nucleus.

• Number of Protons: Equal to the atomic number.

• Number of Neutrons: Calculated as atomic weight minus atomic number.

• Number of Electrons: In a neutral atom, equal to the number of protons.

Example: For Carbon-14 (C-14): Atomic number = 6, Atomic weight = 14, Protons = 6, Neutrons = 8, Electrons = 6.

Key Vocabulary and Definitions

Basic Terms in Chemistry of Life

• Element: A pure substance consisting of only one type of atom.

• Atom: The smallest unit of an element that retains its properties.

• Compound: A substance made of two or more elements chemically combined in fixed ratios.

• Matter: Anything that has mass and takes up space.

• Subatomic Particles:

  • Proton: Positively charged particle in the nucleus.

  • Neutron: Neutral particle in the nucleus.

  • Electron: Negatively charged particle in the electron cloud around the nucleus.

• Nucleus: The central part of an atom containing protons and neutrons.

• Electron Cloud: The region around the nucleus where electrons are likely to be found.

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

• Ion: An atom that has gained or lost electrons, acquiring a charge.

• Chemical Reaction: A process that changes one set of substances into another.

Periodic Table Organization

Structure and Use

• Atomic Number: Organizes elements in order of increasing number of protons.

• Symbol: One- or two-letter abbreviation for an element (e.g., H for hydrogen, Na for sodium).

• Atomic Weight: Average mass of an element’s atoms, accounting for isotopes.

Subatomic Particles and Atomic Structure

Properties and Roles

• Protons: Define the element; number of protons = atomic number.

• Neutrons: Affect the isotope and atomic mass; number of neutrons = atomic mass - atomic number.

• Electrons: Determine chemical behavior and bonding; in neutral atoms, electrons = protons.

Isotopes and Ions

Definitions and Examples

• Isotopes: Atoms of the same element with different numbers of neutrons. Example: Carbon-12 and Carbon-14.

• Ions: Atoms that have gained or lost electrons. Example: Na+ (sodium ion), Cl- (chloride ion).

Application and Real-Life Scenarios

Medical Imaging

• Radioactive isotopes are used in PET scans to trace biological processes. Isotopes differ from normal atoms by having different numbers of neutrons, which can make them unstable or radioactive.

Table Salt Formation

• Sodium (Na) and chlorine (Cl) combine in a chemical reaction to form NaCl (table salt), a compound. This involves the transfer of electrons and the formation of ions.

Photosynthesis

• Plants use carbon dioxide and water to form glucose and oxygen. This process involves chemical reactions and the transformation of matter.

Summary Table: Atomic Structure

Key Equations

• Number of Neutrons:

• Atomic Mass:

Additional info:

• Understanding atomic structure and the periodic table is essential for studying biological molecules and processes, as all living things are composed of atoms and compounds.