1. Hydrogen (H) - Atomic Number: 1
- Lightest and most abundant element in the universe.
- Exists as diatomic gas (H2) in its elemental form.
- Can behave as both a metal and a nonmetal, depending on the chemical context.
- Plays a crucial role in many chemical reactions, including forming water.
- Essential for various industrial and scientific applications.
2. Lithium (Li) - Atomic Number: 3
- Soft, silvery-white metal with a low density.
- Highly reactive with water and air, requiring storage in oil to prevent reaction with moisture.
- Used in rechargeable batteries, ceramics, and heat-resistant glass.
- Medication containing lithium is used for treating bipolar disorder.
- Used in the aerospace industry and as a coolant in nuclear reactors.
3. Sodium (Na) - Atomic Number: 11
- Soft, can be cut with knife, silvery-white metal that tarnishes quickly in air.
- Highly reactive with water, stored in kerosene, producing hydrogen gas and sodium hydroxide.
- Essential for many biological processes in living organisms.
- Sodium compounds, such as sodium chloride (table salt), are commonly used in food and industry.
- Used in various chemical processes, including metallurgy and pharmaceuticals.
4. Potassium (K) - Atomic Number: 19
- Soft, silvery-white metal with a low density.
- Highly reactive with water, releasing hydrogen gas and forming potassium hydroxide.
- Crucial for various biological functions in the human body, including nerve function and muscle contraction.
- An essential nutrient for plants, used as a fertilizer in agriculture.
- Used in the manufacture of soaps, detergents, and certain types of glass.
5. Rubidium (Rb) - Atomic Number: 37
- Soft, silvery-white metal with a low melting point.
- Highly reactive with water and air, igniting spontaneously in air.
- Used in specialized scientific instruments, such as atomic clocks and high-precision magnetometers.
- Certain types of glass contain rubidium for specific properties.
- Rubidium is used in some medical applications, including brain imaging.
6. Cesium (Cs) - Atomic Number: 55
- Soft, silvery-gold metal that is the most reactive of all the alkali metals.
- Highly reactive with water, releasing hydrogen gas and forming cesium hydroxide.
- Used in atomic clocks, where its high atomic frequency provides precise timekeeping.
- Some scientific research applications involve using cesium in experiments.
- Limited practical applications due to its high reactivity and rarity.
7. Francium (Fr) - Atomic Number: 87
- Highly radioactive and extremely rare element.
- Predicted to behave similarly to other alkali metals due to its position in the periodic table.
- Very little is known about its chemical properties due to its rarity and short half-life.
- Francium has limited practical applications due to its extreme scarcity and radioactivity.
- Its discovery and study contribute to our understanding of the periodic table and nuclear decay processes.
