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Elements for Kids

Potassium



<---Argon       Calcium--->
  • Symbol: K
  • Atomic Number: 19
  • Atomic Weight: 39.0983
  • Classification: Alkali metal
  • Phase at Room Temperature: Solid
  • Density: 0.86 grams per cm cubed
  • Melting Point: 63.38°C, 146.08°F
  • Boiling Point: 759°C, 1398°F
  • Discovered by: Sir Humphry Davy in 1807


Potassium is the fourth element in the first column of the periodic table. It is classified as an alkali metal. Potassium atoms have 19 electrons and 19 protons with one valence electron in the outer shell. Potassium is considered chemically similar to sodium, the alkali metal above it on the periodic table.

Characteristics and Properties

Under standard conditions potassium is a soft silvery-white metal. It is so soft that it can be easily cut with a knife. When cut, the exposed metal tarnishes quickly and forms a dull oxide coating.

Potassium has a very low melting point such that even a candle can cause it to melt. When it burns, it produces a pale purple colored flame. Potassium also has a very low density and is the second least dense metal after lithium. It is so light that it can float in water.

Chemically, potassium is a very active metal. It reacts violently when coming into contact with water, producing heat and hydrogen gas. It also reacts with many other elements and substances such as oxygen, acids, sulfur, fluorine, and nitrogen.

Where is potassium found on Earth?

Because potassium reacts so readily with water, it is not found in its elemental form in nature. Instead it is found in various minerals such as sylvite, carnallite, langbeinite, and kainite. Most minerals that contain potassium are referred to as potash.

Making up about 2.1% of the weight of the Earth's crust, potassium is the eighth most abundant element in the crust. It can also be found in ocean water where it is also about the eighth most abundant element.

How is potassium used today?

The largest use of potassium is potassium chloride (KCl) which is used to make fertilizers. This is because potassium is important for plant growth.

Industrial applications for potassium include soaps, detergents, gold mining, dyes, glass production, gunpowder, and batteries.

Potassium also plays a vital role in our bodies. It is used in muscle contraction, fluid and pH balance, bone health, and helps to prevent kidney stones. It is about the eighth most abundant element in the human body by weight.

How was it discovered?

Potassium was first isolated by English chemist Sir Humphry Davy in 1807. He used electricity to separate the element from the salt potash.

Where did potassium get its name?

Potassium gets its name from the salt potash from which potassium was first isolated. The K symbol for the element comes from the Latin word "kalium", which means potash.

Isotopes

There are three isotopes of potassium that occur naturally: K-39, 40, and 41. The majority (93%) of potassium found in nature is K-39.

Interesting Facts about Potassium

More on the Elements and the Periodic Table

Elements
Periodic Table

Alkali Metals
Lithium
Sodium
Potassium

Alkaline Earth Metals
Beryllium
Magnesium
Calcium
Radium

Transition Metals
Scandium
Titanium
Vanadium
Chromium
Manganese
Iron
Cobalt
Nickel
Copper
Zinc
Silver
Platinum
Gold
Mercury
Post-transition Metals
Aluminum
Gallium
Tin
Lead

Metalloids
Boron
Silicon
Germanium
Arsenic

Nonmetals
Hydrogen
Carbon
Nitrogen
Oxygen
Phosphorus
Sulfur
Halogens
Fluorine
Chlorine
Iodine

Noble Gases
Helium
Neon
Argon

Lanthanides and Actinides
Uranium
Plutonium

More Chemistry Subjects

Matter
Atom
Molecules
Isotopes
Solids, Liquids, Gases
Melting and Boiling
Chemical Bonding
Chemical Reactions
Radioactivity and Radiation
Mixtures and Compounds
Naming Compounds
Mixtures
Separating Mixtures
Solutions
Acids and Bases
Crystals
Metals
Salts and Soaps
Water
Other
Glossary and Terms
Chemistry Lab Equipment
Organic Chemistry
Famous Chemists


Science >> Chemistry for Kids >> Periodic Table

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