The main group elements (s- and p-block elements) have some general properties that distinguish them from transition metals. Here’s a summary:
1. Valence Electrons
- Their chemical behavior is determined by the number of electrons in the outermost shell.
- Group number = number of valence electrons (for representative elements).
2. Reactivity
- Reactivity varies across the group:
- Metals (left side) are usually reactive and lose electrons easily.
- Nonmetals (right side) gain or share electrons to form compounds.
3. Physical Properties
- Metals: Soft, shiny, good conductors of heat and electricity, low to moderate melting points (alkali metals are soft).
- Nonmetals: Brittle, dull, poor conductors, lower densities.
- Metalloids: Have mixed properties (semi-conductors).
4. Chemical Properties
- Form ionic compounds (metals with nonmetals).
- Form covalent compounds (nonmetals with nonmetals).
- Tend to form oxides that are either acidic or basic:
- Metals → basic oxides
- Nonmetals → acidic oxides
5. Trends in the Group and Period
- Atomic size: Increases down the group, decreases across a period.
- Ionization energy: Decreases down the group, increases across a period.
- Electronegativity: Decreases down the group, increases across a period.
6. Occurrence and Uses
- Found abundantly in earth’s crust, water, and atmosphere.
- Used in daily life, industry, and biological processes (e.g., sodium, calcium, carbon, nitrogen).
In short: Main group elements are predictable in behavior, with properties depending on their position in the periodic table, and include both metals and nonmetals.