High School Chemistry Unit 2 Study Notes

Objective: Deeper understanding of elements and atomic structure through analysis of the periodic table and prediction of trends.
Lessons:
- Lesson 1: Explore patterns in the periodic table to predict properties of elements.
- Lesson 2: Analyze trends in atomic radius and ionization energy across periods and groups.
- Lesson 3: Draw and interpret Lewis diagrams of atoms and ions based on valence electrons and periodic trends.

CHEM.5: Understanding the development of the periodic table and its predictive power.
- CHEM.5A: Explain the periodic table's development with evidence from chemical and physical properties.
- CHEM.5B: Predict properties of elements in chemical families based on valence electron patterns.
- CHEM.5C: Analyze and interpret elemental data (atomic radius, atomic mass, electronegativity, ionization energy, reactivity) to identify trends.
CHEM.6: Understanding the development of atomic theory and applying it to real-world phenomena.
- CHEM.6E: Construct models expressing electron arrangements using configurations and Lewis structures.

How are elements organized in the periodic table, and why is this system useful?
How can we use patterns in the periodic table for predictions about atomic structure and elemental properties?
How do models like Lewis diagrams help us understand and predict properties of elements?

TEKS Standards: CHEM.5A, B
Objectives:
- Discuss the evolution in the organization of elements.
- Explain Mendeleev’s periodic table, comparing historical and modern versions.
- Classify elements as metals, nonmetals, or metalloids based on properties.
- Predict relative reactivity based on element positions.
- Identify characteristics and locations of chemical families: alkali metals, alkaline earth metals, halogens, noble gases.
- Determine valence electrons in neutral atoms using the periodic table.
Teaching Tips:
- Encourage exploration of periodic table versions and identify patterns.
- Ask students to explore interactive periodic tables for property patterns.
- Utilize the University of Nottingham's Periodic Table of Videos for learning about element properties.
- In group settings, develop common properties and applications of elements.
- Summarize predictions relating to properties based on periodic table positioning:
- Number of protons
- Valence levels
- Valence electrons
- Electron configurations
- Relative reactivity
- Conductivity
- Challenge students to predict properties of a hypothetical element based on its position.
- Design creative periodic tables using everyday items with relevant information.

TEKS Standards: CHEM.5B, C
Objectives:
- Analyze trends in elemental properties through data.
- Explain atomic radius and ionization energy trends across periods/groups.
- Predict comparisons of atomic radii and ionization energies based on positioning.
Teaching Tips:
- Guide students through data graphing of atomic radius and ionization energy as functions of atomic number.
- Emphasize Coulomb’s Law to explain trends in atomic radius and ionization energy:
- Attraction between nucleus and electrons impacted by charge magnitude and distance.
- Increased protons across a period leads to stronger attractive force, reducing atomic radius, raising ionization energy.
- Encourage reasoning behind trends rather than memorization; practice arranging elements by radius or energy.

TEKS Standards: CHEM.5C | CHEM.6E
Objectives:
- Create Lewis diagrams from Bohr models.
- Determine valence electrons from periodic table group numbers.
- Interpret Lewis diagrams for valence electrons identification.
Teaching Tips:
- Implement T-charts to compare Lewis diagrams with Bohr models, assessing advantages/disadvantages.
- Use periodic tables limited to symbols for adding valence electrons in diagrams.
- Reinforce understanding of ion charge behaviors in Lewis diagrams (loss/gain of electrons).
- Conduct games for practice using periodic table resources for drawing diagrams.

Background: Noble metals (gold, silver, platinum) are stable and low-reactive, unlike alkali metals (sodium, potassium) that are highly reactive.
Properties of Noble Metals: Lustrous, malleable, ductile, and resistant to oxidation. E.g., 1 ounce of gold can be hammered into a sheet 0.00018 mm thick, covering 9 square meters.
Understanding Reactivity: Alkali metals oxidize quickly and form compounds, making them undesirable for jewelry.

Critical Concept: Atomic radius decreases left to right across a period, increases down a group due to:
- Core electrons create shielding favoring larger radii.
- Valence electron energy level increases distance, weakening attractive force.
- Increased nuclear charge attracts electrons, favoring smaller radii.
Correction Approach: Connect Coulomb's Law to trends and have students annotate periodic tables based on factors impacting atomic radius.

Critical Concept: These elements are highly reactive and rarely found uncombined in nature, typically existing in compounds.
Correction Approach: Use demonstrations of element reactions, such as sodium's reaction with water, to emphasize their nature in compounds, e.g., sodium chloride.

Types of periodic tables: Explore modern and historical versions.
Royal Society of Chemistry Interactive Periodic Table: Investigate trends.
Periodic Table of Videos: Learn about element properties.
Analysis Tools: Assess periodic trends through provided articles and templates (note-taking, Venn diagrams, graph paper).
Khan Academy Resources: Planning guides, differentiation strategies for varied learning needs, hands-on activities.

Recurring Science Themes: Understanding systems, models, and patterns in science fosters predictive capability. The properties of elements arise from their atomic structures, influencing their reactivity and bonding behavior.