1. Valence Electron: All alkali metals have one valence electron in their outermost shell. This is what defines them as alkali metals and gives them their characteristic reactivity.
2. Number of Electron Shells: The number of electron shells increases as you move down the group. This means Lithium (Li) has 2 shells, Sodium (Na) has 3, Potassium (K) has 4, and so on.
3. Filled Inner Shells: The inner electron shells of alkali metals are completely filled with electrons, except for the outermost shell. This provides stability to the atom.
4. Similar Reactivity: The single valence electron is loosely held and readily participates in chemical reactions, making all alkali metals highly reactive.
5. Similar Chemical Properties: Due to their similar electronic configurations, alkali metals exhibit similar chemical properties. They readily lose their single valence electron to form +1 cations. They react vigorously with water, producing hydrogen gas and a metal hydroxide.
Example:
* Lithium (Li): 2 electrons in the first shell, 1 electron in the second shell.
* Sodium (Na): 2 electrons in the first shell, 8 electrons in the second shell, 1 electron in the third shell.
* Potassium (K): 2 electrons in the first shell, 8 electrons in the second shell, 8 electrons in the third shell, 1 electron in the fourth shell.
As you can see, each element has a different number of shells, but the pattern of filled inner shells and a single valence electron remains consistent, explaining their similar chemical behaviors.
