It cannot be used as a construction material because it is too soft and highly reactive. When burnt, sodium gives a yellow-orange flame. When a tiny piece of sodium is added to water, it shows a highly explosive reaction. Sodium forms a number of compounds that are very useful in laboratories as well as in industries. The salts of sodium are alkaline. Potassium is an alkali metal found among the elements of group I in the periodic table. The electron configuration of potassium is [Ar] 4s 1.
At room temperature, potassium is in the solid phase. The melting point of potassium is Potassium is an element that is absolutely necessary for both plants and animals. Potassium metal is soft and silvery white in color. It has a very low melting point. Since it is a metal, it is a good electrical conductor. Potassium is the seventh most abundant element on earth. Most commercially available compounds are obtained from electrolysis of certain compounds such as carnallite since elemental potassium is present in water-insoluble sediments and rocks, which makes it is difficult to be extracted.
Hence, it is more likely to have ionic bonds with non-metals or anionic compounds through electrostatic attractions. Plants mainly need it for photosynthesis ; it also the primary inorganic cation in the living cell. However, excessive amounts of potassium can be toxic. This means that the alkali metals all have similar chemical properties. When a group 1 element takes part in a reaction, its atoms each lose one electron.
This forms positively charged ions. The ions have a stable arrangement of electrons, with a complete outer shell. The alkali metals react with water to produce a metal hydroxide and hydrogen. For example, sodium reacts with water:. Sodium hydroxide is an alkali. It is a base that dissolves in water to form an alkaline solution. This solution:. Complete the word equation and balanced symbol equation for the reaction of potassium with water.
The table shows observations when lithium, sodium and potassium are added to water. The reactivity of these metals increases going down the group. Rubidium is placed below potassium in group 1. Predict what is seen when rubidium is added to water. Rubidium melts very quickly. It burns violently and explodes. The group 1 elements react with oxygen from the air to make metal oxides. At room temperature, oxygen reacts with the surface of the metal.
This forms a white oxide, which covers the surface. Common salts formed by these metals include sodium chloride and potassium chloride. Both magnesium and calcium are in the second vertical column on the periodic chart. Like all Group 2 elements, magnesium and calcium are alkaline earth metals.
They are both soft, silver-colored metals that react quickly with halogen gases such as fluorine, chlorine and bromine to form salts. Both react with water to form strong basic solutions with a pH greater than 7. This group reacts more slowly with water than Group 1 metals, so magnesium reacts only with steam and calcium requires hot water to form basic solutions. Magnesium and sodium appear next to each other in the third horizontal row, making them period three elements.
Together, they form the S-block of this period. This means that their highest-energy electron is in the S-orbital shell. This configuration explains, in part, why these elements are so very reactive. Potassium and calcium both appear next to each other in the fourth row of the periodic chart, making them period four elements. Like magnesium and sodium, their outer electrons are all in the S shell. All four of these minerals occur in nature.
Deficiencies due to lack of dietary intake are rare because all four are found in most foods.
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