Purpose of Token System

• Flexibility: Allows for managing deadlines and additional attempts.

• Encouragement of Responsibility: Promotes self-regulation and strategic planning among students.

• Stress Reduction: Aims to lessen deadline-related stress while fostering a growth-oriented learning environment.

How Tokens Work

• Management Tool: Tokens assist students in navigating unexpected circumstances or planning.

• Limited Resource: Tokens are a finite resource; wise usage is encouraged.

• Redemption Options: Tokens can exclusively be used for extensions or additional attempts on Real Chem Assignments.

• Request Processing: Requests to redeem tokens are processed Monday through Friday at 9:30 AM by Dr. Bass.

Token Economy in CHEM 101

• Initial Allocation: Students receive 2 tokens at the semester's start.

• Earning Additional Tokens: 6 additional tokens can be earned through participation in selected course activities.

• Redemption Values:

  • 1 token = Module Checkpoint extension or redo.

  • 2 tokens = Unit Checkpoint extension or redo, or Real Chem Exploration extension.

• Request Submission: Forms for redemption are available on Blackboard; they must be submitted for consideration.

Atomic Theory and the Periodic Table

Dalton’s Atomic Theory

• Fundamental Principle: All matter is made of indivisible atoms.

• Element Uniformity: Atoms of the same element are identical in mass and properties.

• Diversity of Elements: Atoms of different elements have distinct masses and properties.

• Compound Formation: Atoms combine in simple whole-number ratios to create compounds.

• Chemical Reactions: Atoms in reactions are combined, separated, or rearranged.

Importance of Dalton

• Foundation of Atomic Theory: Dalton's work is pivotal in progressing our understanding of atomic structure and behavior.

Law of Definite Proportions

• Constant Composition: A compound always contains the same proportion of elements by mass.

  • Example with H2O: Sample data showing consistent ratios of hydrogen to oxygen.

Law of Multiple Proportions

• Ratio of Reactants: When two elements form multiple compounds, the masses of one element that react can be expressed in simple ratios with the masses of the other.

  • Examples: Carbon monoxide (CO) versus Carbon dioxide (CO2).

History of the Atom

Significant Models and Theories

• Historical Progression: Evolution of atomic models from solid sphere to modern theories.

1. John Dalton (1803): Introduced the solid sphere model; defined the atom as indivisible.

2. J.J. Thomson (1904): Discovered the electron; proposed the 'plum pudding' model.

3. Ernest Rutherford (1911): Discovered the nucleus using gold foil experiments; recognized that most of an atom is empty space.

4. Niels Bohr (1913): Modified Rutherford's model; suggested electrons orbit the nucleus at fixed distances with quantized energy levels.

Modern Atomic Theory

• Nucleus Composition: Contains the majority of an atom's mass with protons and neutrons.

• Volume Occupation: Electrons occupy almost all of an atom’s volume.

Subatomic Particles:

Basic Concepts in Atoms

• Atomic Number (Z): Number of protons in the nucleus; defines the element.

• Mass Number (A): Total number of protons and neutrons.

Ions and Isotopes

• Defining Ions: Electrically charged atoms due to unequal numbers of protons and electrons.

  • Cations: Positively charged; e.g., sodium (Na+).

  • Anions: Negatively charged; e.g., oxide (O2-).

Isotopes

• Concept: Atoms with the same number of protons but different neutron counts.

  • Example: Magnesium isotopes 24Mg, 25Mg, and 26Mg each have 12 protons but different neutrons.

Periodic Table Understanding

• Average Atomic Mass: Calculated based on natural abundance of isotopes.

• Chemical Properties: Divided into groups based on similarities: metals, nonmetals, metalloids.

• Structure: Includes main group elements and transition metals.

  • Groups categorized by electron configurations and properties:

    • Transition Metals (Groups 3-13)

    • Main Group Elements (Groups 1, 2, 13-18)

Calculating Average Atomic Mass

• Example - Boron (B):

  • Composed of two isotopes:

    • 19.9% 10B with a mass of 10.0129 amu and 80.1% 11B with a mass of 11.0093 amu.

  • Calculation: Average mass = (0.199 × 10.0129) + (0.801 × 11.0093) = 10.81 amu.

Important Reminders

• Percent abundances of isotopes sum to 100%.

• The periodic table includes the average atomic mass of naturally occurring isotopes.

• Being able to establish relationships between different isotope masses and their abundances is critical for problem-solving.