Matter & Energy


Matter is composed of atoms or groups of atoms called molecules. The arrangement of particles in a material depends on the physical state of the substance. In a solid, particles form a compact structure that resists flow. Particles in a liquid have more energy than those in a solid. They can flow past one another, but they remain close. Particles in a gas have the most energy. They move rapidly and are separated from one another by relatively large distances.

Alkali Metals

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Alkali Metals, series of six chemical elements in group 1 (or Ia) of the periodic table. They are soft compared to other metals, have low melting points, and are so reactive that they are never found in nature uncombined with other elements. They are powerful reducing agents, that is, they give up an electron easily, and react violently with water to form hydrogen gas and hydroxides, or strong bases. The alkali metals are, in order of increasing atomic number, lithium, sodium, potassium, rubidium, cesium, and francium. Francium exists only in a radioactive form.