Group 1 and 2 elements, the s-block metals, are the periodic table's reactive rebels. They're quick to lose electrons, forming positive ions that play nice with water. Their size and charge affect everything from flame colors to how they behave in your body.

These elements are the life of the chemical party. Alkali metals explode in water, while alkaline earth metals are a bit more chill. From batteries to fireworks, these elements make life more exciting and are essential for biological processes.

Periodic Trends

Atomic Properties and Electronic Structure

• Atomic radius decreases across a period and increases down a group due to increased nuclear charge and electron shielding
• Ionization energy generally increases across a period and decreases down a group as electrons become harder to remove from atoms closer to the nucleus
• Electronegativity trends follow ionization energy, increasing across periods and decreasing down groups as atoms gain more affinity for electrons
• Electron configuration determines an element's chemical properties, following the Aufbau principle, Hund's rule, and Pauli exclusion principle

Chemical Behavior and Relationships

• Oxidation state represents the degree of oxidation of an atom in a compound, ranging from -4 to +8 for main group elements
• Diagonal relationship occurs between elements diagonally adjacent in the periodic table (Li-Mg, Be-Al, B-Si), exhibiting similar properties due to comparable charge density and size
• Anomalous behavior manifests in certain elements deviating from expected trends (Be, B, C, N, O) due to small size and high charge density

Group 1: Alkali Metals

Physical and Chemical Properties

• Alkali metals comprise the elements in Group 1 of the periodic table (Li, Na, K, Rb, Cs, Fr), characterized by a single valence electron
• Reactivity increases down the group as atomic size increases and ionization energy decreases, making it easier to lose the valence electron
• Flame test produces characteristic colors for each alkali metal (Li-red, Na-yellow, K-lilac, Rb-red-violet, Cs-blue) due to electron excitation and relaxation

Aqueous Behavior and Applications

• Hydration energy decreases down the group as ionic radius increases, affecting solubility and reactivity in aqueous solutions
• Alkali metals react vigorously with water, producing hydrogen gas and metal hydroxides (2M + 2H2O → 2MOH + H2)
• Applications include sodium vapor lamps, lithium batteries, and potassium as a biological electrolyte

Group 2: Alkaline Earth Metals

Chemical Characteristics and Reactivity

• Alkaline earth metals include elements in Group 2 of the periodic table (Be, Mg, Ca, Sr, Ba, Ra), with two valence electrons
• Reactivity increases down the group but is generally less than alkali metals due to higher ionization energies and smaller atomic radii
• Flame test produces distinct colors for alkaline earth metals (Be-colorless, Mg-bright white, Ca-brick red, Sr-crimson, Ba-green) useful for analytical chemistry

Coordination Chemistry and Applications

• Coordination number typically ranges from 6 to 8 for alkaline earth metals, influencing their chemical behavior and complex formation
• Alkaline earth metals form divalent cations (M²⁺) in aqueous solutions, contributing to water hardness (Ca²⁺ and Mg²⁺)
• Applications include magnesium alloys in aerospace, calcium in cement production, and strontium in pyrotechnics