Overview
This lecture introduces the structure, organization, and key groups of the periodic table, highlighting important element categories and their properties.
Periodic Table Structure
- The periodic table is arranged in vertical columns called groups (1-18) and horizontal rows called periods (1-7).
- Elements within the same group share similar chemical properties due to their valence electrons.
Major Element Groups
- Alkali metals (Group 1) have one valence electron, are highly reactive, and react explosively with water.
- Alkaline earth metals (Group 2) have two valence electrons, are reactive, and commonly form oxides.
- Halogens (Group 17) have seven valence electrons, are highly reactive, and are often found as gases.
- Noble gases (Group 18) have full outer electron shells (eight valence electrons) and are extremely stable and inert.
Nonmetals and SCHNOPS
- SCHNOPS (Sulfur, Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Selenium) are key nonmetals vital for living organisms.
- Each SCHNOPS element plays an essential biological role (e.g., carbon in structures, oxygen in energy).
Transition Metals and Other Metals
- Transition metals are located in the central block and have variable numbers of valence electrons, leading to diverse properties.
- Poor metals are to the right of transition metals and include elements like gallium, which has a low melting point.
Metalloids and Semiconductors
- Metalloids (e.g., boron, silicon) have properties between metals and nonmetals and can semi-conduct electricity.
- Silicon is widely used in electronics as a semiconductor material.
Trends and Other Features
- Atom size increases as you move down the periodic table; elements at the bottom (like uranium) are larger and often radioactive.
- Lanthanides and actinides are typically shown separately at the bottom but fit within the main table.
Key Terms & Definitions
- Group — column of elements with similar properties and the same number of valence electrons.
- Period — row of elements with increasing atomic number.
- Alkali Metals — highly reactive metals in Group 1 with one valence electron.
- Alkaline Earth Metals — metals in Group 2 with two valence electrons.
- Halogens — highly reactive nonmetals in Group 17 with seven valence electrons.
- Noble Gases — inert gases in Group 18 with full valence shells.
- Transition Metals — central block elements with variable valence electrons.
- Metalloids — elements with properties between metals and nonmetals, often semiconductors.
Action Items / Next Steps
- Review the organization and properties of periodic table groups.
- Explore videos or demonstrations on alkali metals’ reactions with water.
- Read about the history of the periodic table for additional context (optional: "The Disappearing Spoon" by Sam Kean).