Símbolo | K |
Número atómico | 19 |
Grupo | 1 (Alcalino) |
Período | 4 |
Bloque | s |
Clasificación | Alcalino |
Apariencia | Silvery gray |
Color | Plata |
Número de protones | 19 p+ |
Número de neutrones | 20 n0 |
Número de electrones | 19 e- |
Fase en STP | Sólido |
Densidad | 0.862 g/cm3 |
Peso atómico | 39.0983 u |
Punto de fusión | 336.7 K 63.55 °C 146.39 °F |
Punto de ebullición | 1032 K 758.85 °C 1397.93 °F |
Entalpía de vaporización | 76.9 kJ/mol |
Electronegatividad (Escala de Pauling) | 0.82 |
Afinidad electrónica | 48.383 kJ/mol |
Estado de oxidación | −1, +1 (a strongly basic oxide) |
Energía de ionización |
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Descubrimiento y primer aislamiento | Humphry Davy (1807) |
Descubrimiento de potasio The English name for the element potassium comes from the word potash, which refers to an early method of extracting various potassium salts: placing in a pot the ash of burnt wood or tree leaves, adding water, heating, and evaporating the solution. When Humphry Davy first isolated the pure element using electrolysis in 1807, he named it potassium, which he derived from the word potash. The symbol K stems from kali, itself from the root word alkali, which in turn comes from Arabic: القَلْيَه al-qalyah 'plant ashes'. In 1797, the German chemist Martin Klaproth discovered "potash" in the minerals leucite and lepidolite, and realized that "potash" was not a product of plant growth but actually contained a new element, which he proposed calling kali. In 1807, Humphry Davy produced the element via electrolysis: in 1809, Ludwig Wilhelm Gilbert proposed the name Kalium for Davy's "potassium". In 1814, the Swedish chemist Berzelius advocated the name kalium for potassium, with the chemical symbol K. |