Periodic Table of Elements - Quarter 1, Lesson 3

Essential Learning Competencies

• Differentiate between atomic number, mass number, and isotopes.
• Identify elements based on their distinguishing features.

Learning Objectives

• Understand the periodic law and element organization in the periodic table.
• Predict properties of elements based on their periodic table location.
• Classify metals, nonmetals, and metalloids by properties and placement.

Historical Context

• Early chemists grouped elements by similar behaviors; examples include:
  • Li, Na, K: reactive, shiny, good conductors.
  • Ca, Sr, Ba: less reactive, also shiny and conductive.
• Dimitri Mendeleev (1869) and Lothar Meyer (1870) organized elements by increasing atomic mass and recognized periodic relationships.
• Mendeleev predicted undiscovered elements (e.g., gallium, germanium) based on his table, gaining support for his work.

Modern Periodic Law

• Modern periodic law states that element properties are periodic functions of atomic numbers, not masses.
• The periodic table is arranged by increasing atomic numbers, grouping similar properties in vertical columns.

Understanding the Periodic Table

• Atomic Number: Number of protons in an element; unique to each element.
• Atomic Mass: Sum of protons and neutrons; represents the weight of the atom.
• Isotopes: Atoms with identical protons but differing neutrons.

Chemical Symbols

• Each element has a unique symbol, either a single capital letter or a combination of capital and lowercase letters.

States of Matter

• Most metals (except Hg) are solids; some are softer (e.g., Li, Na) while others are harder (e.g., Cu, Fe).
• Nonmetals predominantly exist as gases; exceptions include solid forms like sulfur and phosphorus.
• Metalloids exhibit properties of both metals and nonmetals.

Classification of Elements

• Metals:
  • Good conductors of heat/electricity, shiny, ductile, and malleable.
  • Reactive, especially with water.
• Nonmetals:
  • Poor conductors, brittle if solid, dull appearance, often gaseous.
• Metalloids:
  • Intermediate properties, can be shiny or dull, better conductors than nonmetals but less than metals.

Periods and Groups

• Elements are arranged in:
  • Horizontal Rows (Periods): No similar property correlation.
  • Vertical Columns (Groups/Families): Similar properties among elements in the same column.

Specific Groups in the Periodic Table

• The periodic table includes:
  • Main-group elements (columns 1, 2, 13-18).
  • Transition metals (columns 3-12).
  • Inner transition metals (lanthanides and actinides).

Alkali Metals

• Located in Group 1, characterized by:
  • Shiny appearance, clay-like consistency, and softness.
  • Highly reactive, especially with water; not found uncombined in nature.

Alkaline Earth Metals

• Found in Group 2:
  • Have two valence electrons, including magnesium and calcium.
  • Also reactive, but less so than alkali metals; not found uncombined in nature.

Reactivity Concepts

• Reactivity relates to incomplete valence electron levels; atoms achieve stability by completing their outer shells.
• Atoms with fewer valence electrons tend to lose them; those with 6, 7, or 8 gain during bonding.

This quiz covers key concepts from the periodic table of elements, including atomic number, mass number, and isotopes. Students will explore the organization of elements and learn how to predict general properties based on their locations. It’s designed for STEM students and aligns with essential learning competencies.