Podcast
Questions and Answers
What is the primary reason for the high reactivity of alkali metals?
Which metal reacts with nitrogen to form lithium nitride?
Which type of oxide is produced when sodium reacts with oxygen?
What is the expected product when potassium reacts with water?
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How do heavier alkali metals react with water compared to lighter alkali metals?
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When alkali metals react with hydrogen, what type of compounds are formed?
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What type of compounds do alkali metals form when they react with sulfur?
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Which alkali metal is less reactive with water compared to the rest?
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What happens to the outermost shell electrons of Group I & II elements when they are heated?
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Which of the following correctly describes the flame test?
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What color is emitted when Lithium (Li) is tested in a flame test?
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Why do metals emit light when heated in a flame test?
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Which of these flame colors is associated with Strontium (Sr) in a flame test?
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Which of the following statements about lithium is correct?
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What is the solubility characteristic of lithium salts compared to other alkali metal salts?
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Which alkali metal is noted for its significant industrial use and versatility?
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Why is lithium considered to have a greater covalent character in its compounds?
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What is a unique reaction characteristic of lithium compared to group IA elements?
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What is the primary reason the alkali metals are referred to as 'alkali'?
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Which of the following alkali metals has the highest boiling point?
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What common property do alkali metals share in their atomic structure?
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Which alkali metal is considered to have the lowest density?
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What type of structure do alkali metals form when crystallized?
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How do alkali metals typically react with nonmetals?
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Which alkali metal is the most abundant on Earth?
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Which of the following alkali metals has the lowest melting point?
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Which metal uniquely reacts with carbon to form lithium carbide?
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What is a characteristic of metallic bonding?
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How does an increase in ionic radius affect the strength of metallic bonding?
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What trend is observed in the melting points of group IA metals?
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Which of the following statements is true regarding lithium compared to other group IA elements?
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What role do delocalized electrons play in metallic bonding?
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Which factor contributes to stronger metallic bonding between metal ions?
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What is likely the state of cesium at room temperature based on its melting point?
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Study Notes
Alkali Metals (Group IA)
- Alkali metals are highly reactive
- They are typically found in nature combined with other elements.
- Their high reactivity is due to their large atomic radii and low ionization energies (only one valence electron).
- They easily form ionic compounds
- Alkali metals are the most electropositive (least electronegative) elements.
- Lithium is less reactive than other alkali metals with water, oxygen, and halogens, but more reactive with nitrogen, carbon, and hydrogen
Properties of Alkali Metals
-
Atomic radius (nm):
- Li: 0.152
- Na: 0.186
- K: 0.231
- Rb: 0.244
- Cs: 0.262
- Fr: 0.270
-
Ionic radius (nm):
- Li: 0.060
- Na: 0.095
- K: 0.133
- Rb: 0.148
- Cs: 0.169
- Fr: 0.176
-
Melting point (°C):
- Li: 180.5
- Na: 97.8
- K: 63.7
- Rb: 39.1
- Cs: 28.4
- Fr: 27
-
Boiling point (°C):
- Li: 1330
- Na: 890
- K: 774
- Rb: 688
- Cs: 690
- Fr: 680
-
Density (g cm⁻³):
- Li: 0.53
- Na: 0.97
- K: 0.86
- Rb: 1.53
- Cs: 1.87
- Fr: Trace
-
Abundance on earth (%):
- Li: 0.0020
- Na: 2.36
- K: 2.09
- Rb: 0.0090
- Cs: 0.00010
- Fr: Trace
Reaction with Oxygen
- Different alkali metals react with oxygen to form different oxides
- Li forms normal oxide (Li₂O)
- Na forms normal oxide (Na₂O) and peroxide (Na₂O₂).
- K forms normal oxide (K₂O), peroxide(K₂O₂), and superoxide (KO₂).
- Rb forms normal oxide, peroxide, and superoxide.
- Cs forms normal oxide, peroxide, and superoxide.
Reaction with Water
- All alkali metals react with water to produce heat, hydrogen gas, and the corresponding metal hydroxide.
- Heavier alkali metals react more violently with water
Reaction with Hydrogen
- Alkali metals react with hydrogen to form ionic hydrides
Reaction with Sulfur
- Alkali metals react with sulfur to form sulphides (M₂S) and polysulphides (M₂Sₙ, n = 2, 3, 4, 5, or 6).
Reaction with Carbon
- Lithium is the only alkali metal that reacts directly with carbon to form lithium carbide (Li₂C₂).
- Sodium and potassium can react with acetylene (C₂H₂) to form metal carbides(acetylides)
- sodium and potassium also react with methane to give metal carbide(acetylides)
Metallic Bond
- The metallic bond involves the sharing of many detached electrons between many positive ions.
- The electrons act as a "glue" to form a definite structure
- In contrast to ionic and covalent bonding
- Metals have low ionization energies, allowing valence electrons to delocalize.
- The delocalized electrons form a "sea" of electrons, providing a negative charge cloud that attracts positive ions.
- The electrostatic attraction between these electrons and ions holds the structure together.
- This explains high melting points and boiling points of metals.
Flame Test
- A flame test is used to detect metal ions based on their characteristic emission spectrum.
- Heating the metal causes electrons to be promoted to higher energy levels.
- When the electrons fall back to their ground states, they emit light
- The colors of emitted are characteristic of the metal.
- The specific wavelengths (colors) of emitted light are unique to each element.
Differences between Lithium and Other Alkali Metals
- Lithium has higher melting and boiling points compared to other alkali metals.
- Lithium is harder than other alkali metals.
- Lithium is less electropositive than other alkali metals.
- Lithium forms a normal oxide, while other alkali metals typically form peroxides and superoxides.
- Lithium reacts with nitrogen to form nitride(Li₃N)
- Lithium compounds are heavily hydrated compared to other alkali metals.
- Lithium has a greater tendency to form complexes due to its smaller size,complex formation decreases with increasing radius.
- The covalent character in its compounds is greater than expected due to its smaller size, high ionization energy, and high electronegativity.
- Lithium halides and alkyls are soluble in organic solvents due to the covalent nature of the bonds.
- Some Lithium salts are insoluble in water unlike salts of other alkali metals(example, Li₂CO₃, Li₃PO₄, LiF)
Industrial Uses
- Sodium is the most important alkali metal for industrial use, used in organic compound reduction and various compound preparation.
- Potassium salts are crucial in fertilizer manufacturing.
- Lithium is used in lightweight metal alloys and as a catalyst in organic syntheses, and also in lightweight batteries.
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Description
Test your knowledge on the properties and reactivity of alkali metals in Group IA. This quiz covers key concepts such as atomic radius, ionic radius, and their interaction with other elements. Discover how lithium compares to other alkali metals and understand their significance in chemistry.
