Group 1: Li, Na, K, Rb, Cs, Fr. Configuration [noble gas] $ns^1$. Trends down the group: Atomic radius increases, IE decreases (520 → 376 kJ/mol), electronegativity decreases, metallic character increases, reactivity with water increases. All are strong reducing agents (large negative $E^0$ values). Electrode potentials: Li has the most negative $E^0$ (-3.04 V), making it the strongest reducing agent in aqueous solution despite having the highest IE — because $Li^+$ has very high hydration energy (small ion, strong ion-dipole interactions). Flame test works because thermal energy promotes $ns^1$ electron; the emitted photon on de-excitation has visible wavelength. All alkali metals are stored under kerosene (react with air and moisture).