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Potassium - Definition, Symbol, Structure, Properties, Uses, FAQs

Potassium - Definition, Symbol, Structure, Properties, Uses, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:53 PM IST

In this article we will discuss everything about potassium, potassium element, atomic mass of potassium, potassium symbol, potassium atomic number, uses of potassium, K element, mass number of potassium, atomic weight of potassium, potassium periodic table, potassium group number, potassium electrons, k element name, potassium chemical, potassium name and electronic structure of potassium.

This Story also Contains
  1. What is potassium?
  2. What is the symbol of potassium?
  3. What is the atomic number of potassium?
  4. What is the mass of potassium?
  5. What are the uses of potassium?
  6. Properties of potassium

What is potassium?

Metallic potassium was first isolated in 1807 by Sir Humphry Davy. He obtained a potassium element through the electrolysis of molten caustic potash (KOH) using a voltaic battery. The name potassium is derived from potash. It is the lightest known metal with lithium as its predecessor. It is soft enough to be easily cut with a knife. It is silvery-white in appearance and rapidly oxidizes in air. Potassium element is the 8th most abundant element on earth. About 2.1% of Potassium element is present in earth's crust.

Background wave

It is a very reactive element and is never found free in nature because it reacts very rapidly with oxygen present in the atmosphere to form potassium peroxide within seconds of exposure. Thus, potassium element must be preserved in a mineral oil like kerosene. Salty bodies of water are rich in potassium and the estimated potassium content of the Dead Sea is approximately 1.7 %. Potassium that is part of earth crust is present in igneous rocks and minerals that are insoluble in water. This is why obtaining potassium is difficult.

Potassium that is part of earth crust is present in igneous rocks and minerals that are insoluble in water. This is why obtaining potassium is difficult.

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What is the symbol of potassium?

The symbol for potassium is K which is derived from its neo-Latin name kalium. Potassium K group number is 1 or IA and period number is 4th on the periodic table. Potassium K element is part of the alkali metal group which consist of lithium, sodium, potassium, rubidium, caesium, and francium.

The symbol for potassium is K which is derived from its neo-Latin name kalium. Potassium K group number is 1 or IA and period number is 4th on the periodic table. Potassium K element is part of the alkali metal group which consist of lithium, sodium, potassium, rubidium, caesium, and francium.

What is the atomic number of potassium?

The atomic number of potassium K is 19. This is due to the presence of nineteen potassium electrons in different orbits of atoms of k element. The atomic structure of potassium is given below:

Potassium K atomic number is due to presence of two electrons in K shell, eight electron in L and M shell and one electron in N shell. The last electron is easily lost from potassium atom to form potassium ion K+ which leads to decrease in atomic no of K potassium. The atomic number of K + is 18. The electronic structure of potassium can be represented as 1s22s22p63s23p64s1 or [Ar]4s1.

Potassium K atomic number is due to the presence of two electrons in K shell, eight electrons in L and M shell and one electron in N shell. The last electron is easily lost from the potassium atom to form potassium ion K+ which leads to decrease in atomic no of K potassium. The atomic number of K + is 18. The electronic structure of potassium can be represented as 1s22s22p63s23p64s1 or [Ar]4s1.

What is the mass of potassium?

The atomic mass of K is 39.0983 u. The atomic weight of potassium is the same a mass number of potassium; 39.0983 u. The value of potassium mass and atomic no of potassium with chemical symbol of potassium is written as:

39.10 is K atomic mass or atomic weight of k and 19 is atomic number of potassium.

Where, 39.10 is K atomic mass or atomic weight of k and 19 is atomic number of potassium.

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What are the uses of potassium?

Most of the manufactured potassium is used in fertilizers, a potassium compound potassium chloride KCl is used as a salt substitute in fertilizers and to produce other important chemicals.

Another important potassium compound is potassium hydroxide which is used in manufacturing of soaps, liquid cleaners and detergents.

Potassium carbonate is also a widely used compound used for manufacturing of glass and commonly known as pearl ash.

Other salts of potassium are used in tanning leather, baking, in ionized salt and in photography. Potassium is a macronutrient that helps in plant growth and constitutes most soils. Sodium combines with potassium to form an alloy which is used as a heat transfer medium.

There is a balance between the K+ and Na+ concentrations inside and outside the cells in our bodies. Potassium-sodium pump is also an essential part of cell metabolism. Potassium ions are transported across the biological membranes through proteins known as potassium channels.

Disease caused due to deficiency of potassium: Hypokalemia is caused due to low levels of potassium in blood. Potassium helps in the functioning of cells and acts as an electrolyte for nerve cells as well. It is also essential for muscle cell functioning. Kidneys control potassium levels in our body and help in excretion of excess potassium through urine or sweat.

Potassium comes with many health benefits, it may:

  • Reduce water retention

  • Help prevent kidney stones

  • Help protect against strokes

  • Help reduce blood pressure

  • Help prevent osteoporosis

Potassium is rich in a lot of whole foods, fruits, vegetables and fish. Fruits like Bananas, oranges, cantaloupe, honeydew, apricots, and grapefruit are also rich in potassium. Some cooked vegetables like cooked spinach, broccoli potatoes sweet, potatoes, mushrooms, peas, cucumbers, zucchini, pumpkins, and leafy greens are abundant in potassium. Some dry fruits like prunes, raisins and dates are also high in potassium.

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Properties of potassium

Physical and chemical properties of potassium are given as:

Physical properties of potassium

Potassium melting point is very low with a value 63.65oC. The boiling point of potassium is 773.9oC.Potassium is silvery-white in appearance. Potassium is a very soft solid. It can easily be cut with a knife.

Chemical properties of potassium

Potassium vigorously reacts with atmospheric oxygen to form potassium peroxide. Potassium reacts vigorously with water in a violent exothermic reaction to form potassium hydroxide. Atomic radius of potassium is 227pm and ionization enthalpy is 418.8kJ/mol. Electronegativity of potassium is 0.8.

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Frequently Asked Questions (FAQs)

1. What is the symbol of potassium?

 The symbol of potassium is K which is derived from its neo-Latin name kalium.

2. What is the atomic mass of potassium?

The mass no of potassium is 39.0983 u.

3. What is atomic number of potassium?

Potassium atomic no is 19 which means nineteen electrons are present in atomic orbits.

4. Who discovered potassium?

 Potassium was discovered by English chemist Sir Humphry Davy in 1807.

5. What is potassium used for?

Most of the manufactured potassium is used in fertilizers, a potassium compound potassium chloride KCl is used as a salt substitute in fertilizers and to produce other important chemicals. Another important potassium compound is potassium hydroxide which is used in manufacturing of soaps, liquid cleaners and detergents. Potassium carbonate is also a widely used compound used for manufacturing of glass and commonly known as pearl ash. Other salts of potassium are used in tanning leather, baking, in ionized salt and in photography. Potassium is a macronutrient that helps in plant growth and is the constituent of most soils. Sodium combines with potassium to form an alloy which is used as a heat transfer medium.

There is a balance between the K+ and Na+ concentrations inside and outside the cells in our bodies. Potassium-sodium pump is also an essential part of cell metabolism. Potassium ions are transported across the biological membranes through proteins known as potassium channels.

Disease caused due to deficiency of potassium: Hypokalemia is caused due to low levels of potassium in blood. Potassium helps in the functioning of cells and acts as an electrolyte for nerve cells as well. It is also essential for muscle cell functioning. Kidneys control potassium levels in our body and help in excretion of excess potassium through urine or sweat.

Potassium comes with many health benefits, it may:

  • Reduce water retention

  • Help prevent kidney stones

  • Help protect against strokes

  • Help reduce blood pressure

  • Help prevent osteoporosis 

Potassium is rich in a lot of whole foods, fruits, vegetables and fish. Fruits like Bananas, oranges, cantaloupe, honeydew, apricots, and grapefruit are also rich in potassium. Some cooked vegetables like cooked spinach, broccoli potatoes sweet, potatoes, mushrooms, peas, cucumbers, zucchini, pumpkins, and leafy greens are abundant in potassium. Some dry fruits like prunes, raisins and dates are also high in potassium

6. Define potassium.

Potassium is an alkali metal with atomic number 19. It is soft silvery- white in appearance.

7. Is potassium malleable?

 Potassium has qualities of metals. Thus, it is malleable and ductile.

8. How does the atomic structure of potassium contribute to its reactivity?
Potassium's atomic structure consists of 19 protons and 19 electrons. Its electron configuration is [Ar] 4s¹, with one valence electron in the outermost shell. This single valence electron is easily lost, making potassium highly reactive. The large atomic radius and low ionization energy further contribute to its high reactivity.
9. What is the flame test color for potassium, and why does it produce this color?
Potassium produces a lilac or pale violet color in a flame test. This occurs because when heated, the outermost electron of potassium atoms becomes excited and jumps to a higher energy level. When it falls back to its ground state, it emits energy in the form of light with a specific wavelength, resulting in the characteristic lilac color.
10. How does potassium compare to other alkali metals in terms of reactivity?
Potassium is more reactive than lithium and sodium but less reactive than rubidium and cesium in the alkali metal group. This trend is due to increasing atomic size and decreasing ionization energy as we move down the group, making it easier for the outermost electron to be removed.
11. Why is potassium stored in oil?
Potassium is stored in oil to prevent it from reacting with oxygen and moisture in the air. As a highly reactive metal, potassium can ignite spontaneously when exposed to air and reacts vigorously with water. The oil acts as a barrier, protecting the metal from these elements and ensuring its preservation.
12. What is the significance of potassium's low first ionization energy?
Potassium's low first ionization energy is significant because it indicates how easily the atom can lose its outermost electron to form a cation (K⁺). This property contributes to potassium's high reactivity and its tendency to form ionic compounds. It also explains why potassium readily participates in biological processes, such as nerve signal transmission.
13. What is potassium and where is it found in the periodic table?
Potassium is an alkali metal element with the symbol K and atomic number 19. It is found in the first group (Group 1) and fourth period of the periodic table, making it an s-block element. Potassium is highly reactive and is never found as a free element in nature due to its reactivity with water and oxygen.
14. What is the role of potassium in biological systems?
Potassium plays crucial roles in biological systems, including:
15. What is the oxidation state of potassium in its compounds, and why?
Potassium typically has an oxidation state of +1 in its compounds. This is because potassium, like other alkali metals, tends to lose its single valence electron to achieve a stable electron configuration similar to the nearest noble gas (argon in this case). The loss of one electron results in a +1 oxidation state.
16. How does potassium form chemical bonds, and what types of compounds does it typically form?
Potassium primarily forms ionic bonds due to its low electronegativity and tendency to lose its single valence electron. It typically forms compounds with non-metals, where potassium becomes a cation (K⁺) and the non-metal becomes an anion. Examples include KCl (potassium chloride) and KOH (potassium hydroxide). Potassium rarely forms covalent bonds.
17. How does potassium contribute to the action potential in nerve cells?
Potassium plays a crucial role in the action potential of nerve cells:
18. How does the electronic configuration of potassium explain its chemical behavior?
Potassium's electronic configuration ([Ar] 4s¹) explains its chemical behavior:
19. How does the concept of effective nuclear charge explain the trends in atomic and ionic radii of potassium compared to other elements in its period and group?
The concept of effective nuclear charge explains atomic and ionic radii trends for potassium:
20. How does potassium's first ionization energy compare to its second ionization energy, and what does this reveal about its chemical behavior?
Potassium's first and second ionization energies reveal important aspects of its chemical behavior:
21. How does the atomic radius of potassium compare to sodium, and why?
Potassium has a larger atomic radius than sodium. This is because potassium is in the fourth period while sodium is in the third. As we move down a group in the periodic table, the number of electron shells increases. The additional shell in potassium results in a larger atomic radius, despite the increased nuclear charge.
22. How does the isotopic composition of potassium contribute to radioactive dating techniques?
Potassium's isotopic composition, particularly potassium-40, is crucial for radioactive dating:
23. Why does potassium have the symbol 'K' instead of 'P'?
The symbol 'K' for potassium comes from the Latin word 'kalium'. This name was derived from the Arabic word 'al-qali', meaning "plant ashes," as potassium was first isolated from wood ashes. The symbol 'P' was already assigned to phosphorus when potassium was discovered.
24. What are some common uses of potassium compounds in everyday life?
Potassium compounds have various uses in everyday life:
25. What role does potassium play in the production of fertilizers, and why is it important for agriculture?
Potassium plays a crucial role in fertilizer production and agriculture:
26. What is the biological significance of the potassium-sodium pump in cell membranes?
The potassium-sodium pump (Na⁺/K⁺-ATPase) in cell membranes is biologically significant because:
27. What are the environmental implications of increased potassium use in agriculture?
The increased use of potassium in agriculture has several environmental implications:
28. How does potassium react with water, and what are the products?
Potassium reacts vigorously with water, producing potassium hydroxide (KOH) and hydrogen gas (H₂). The reaction is exothermic and can be represented as: 2K + 2H₂O → 2KOH + H₂. The reaction is so vigorous that the hydrogen gas produced often ignites, creating a lilac flame characteristic of potassium.
29. What is the significance of potassium's relatively low melting and boiling points compared to other metals?
Potassium's relatively low melting point (63.5°C) and boiling point (759°C) compared to other metals are due to its weak metallic bonding. The single valence electron of each potassium atom is loosely held, resulting in weaker inter-atomic forces. This property is characteristic of alkali metals and contributes to their softness and low density.
30. How does the reactivity of potassium change when it forms an ion, and why?
When potassium forms an ion (K⁺), its reactivity significantly decreases. This is because the K⁺ ion has a stable electron configuration identical to the noble gas argon. The loss of the single valence electron results in a much more stable entity, which is less likely to participate in further chemical reactions compared to the highly reactive neutral potassium atom.
31. Why is potassium considered a macro-nutrient for plants?
Potassium is considered a macro-nutrient for plants because it is required in large quantities for proper plant growth and development. It plays several crucial roles:
32. What is the difference between potassium metal and potassium ions in terms of properties and behavior?
Potassium metal and potassium ions differ significantly:
33. Why does potassium form superoxides (KO₂) rather than normal oxides when burned in excess oxygen?
Potassium forms superoxides (KO₂) rather than normal oxides because:
34. How does the hydration energy of potassium ions compare to that of sodium ions, and what are the implications?
The hydration energy of potassium ions is lower than that of sodium ions:
35. What is the significance of potassium's position in the electrochemical series?
Potassium's position in the electrochemical series is significant because:
36. How does the coordination number of potassium ions in crystals compare to that of sodium ions, and why?
The coordination number of potassium ions in crystals is typically higher than that of sodium ions:
37. How does the solubility of potassium compounds generally compare to those of other alkali metals, and why?
The solubility of potassium compounds generally follows these trends:

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Option 1: Calcium hydroxide

Option 2: Potassium hydroxide

Option 3: Magnesium hydroxide

Option 4: Ammonium hydroxide

Correct Answer: Calcium hydroxide


Solution : The correct answer is Calcium hydroxide.

Lime water contains calcium hydroxide, which is a strong base. The chemical formula for calcium hydroxide is Ca(OH)2. When calcium oxide (quicklime) reacts with water, it forms calcium hydroxide, resulting in lime water. The hydroxide ions (OH⁻) from calcium hydroxide make it a base.

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Question : Rearrange the parts of the sentence in the correct order.
Electrolytes like
P. important for balancing the water in your body
Q. are present in the body’s fluids and are
R. are electrically charged minerals that
S. sodium, potassium, chloride, and magnesium

Option 1: PQSR

Option 2: SPRQ

Option 3: SQRP

Option 4: SRQP

Correct Answer: SRQP


Solution : The correct order of the parts of the sentence is in the fourth option i.e. SRQP.

Explanation:

  1. S. This part lists specific examples of electrolytes, providing details about the types of minerals being discussed.
  2. R: This part introduces the topic, mentioning the category of substances being discussed, which is electrolytes.
  3. Q: This part provides additional information about electrolytes, specifying their presence in the body's fluids.
  4. P: This part explains the significance of electrolytes, emphasising their role in balancing the water in the body.

So, the correct sentence would be: "Electrolytes like sodium, potassium, chloride, and magnesium are present in the body’s fluids and are important for balancing the water in your body."

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Question : Which of the following is not soluble in water?

Option 1: Lead sulphate

Option 2: Zinc sulphate

Option 3: Potassium sulphate

Option 4: Sodium sulphate

Correct Answer: Lead sulphate


Solution : The correct option is Lead sulphate.

Lead sulphate is considered insoluble in water and forms a solid precipitate when lead ions (Pb²⁺) and sulphate ions (SO₄²⁻) combine in a solution. The other compounds mentioned—zinc sulphate (ZnSO4), potassium sulphate (K2SO4), and sodium sulphate (Na2SO4)—are all soluble in water.

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a. Many fitness trainers encourage their clients to include these foods in their diet to build muscles.
b. Power foods can be included in your everyday diet in a variety of ways.
c. The secret to getting the most out of power foods is, of course, knowing how to cook them properly, buying seasonal produce, and recognising your preferred flavour profile.
d. Power foods are high in nutrients such as fibre, potassium, and minerals.

Option 1: d, b, c, a

Option 2: d, a, b, c

Option 3: b, c, a, d

Option 4: a, d, b, c

Correct Answer: d, a, b, c


Solution : The correct choice is the second option.

Explanation:
The paragraph starts by introducing the concept of power foods in sentence d, explaining that they are rich in essential nutrients. This sets the stage for understanding the significance of these foods in a diet. Following this, sentence a links the importance of power foods to fitness trainers encouraging their clients to include them for muscle building, highlighting their practical application in fitness regimes. Then, sentence b broadens the scope by suggesting that power foods can be easily incorporated into daily meals, emphasising their versatility. Finally, sentence c concludes by offering guidance on maximising the benefits of these foods through proper cooking methods, seasonal produce selection, and understanding flavour preferences, thereby providing a comprehensive approach to making the most of power foods in one's diet.

Therefore, the correct answer is d, a, b, c.

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