What are alkali metals?
Alkali metals are elements located in Group 1 of the periodic table, excluding hydrogen. They include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). They are known for their high reactivity due to their single valence electron.
- What are alkaline earth metals?
Alkaline earth metals are elements in Group 2 of the periodic table. They include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). They are less reactive than alkali metals but still form salts readily.
- What distinguishes alkali metals from alkaline earth metals?
Alkali metals have one valence electron in their outermost shell which they readily lose to form a +1 ion. Alkaline earth metals have two valence electrons, which they can lose to form a +2 ion.
- Why are alkali metals stored in oil?
Alkali metals are stored in oil to prevent them from reacting with the oxygen and moisture in the air. They are so reactive that they can spontaneously ignite or even explode when exposed to air or water.
- What is the trend in reactivity among alkali metals?
The reactivity of alkali metals increases as you move down the group on the periodic table. This is due to the increasing atomic radius and the outermost electron being further from the nucleus, making it easier to lose.
- What is the trend in reactivity among alkaline earth metals?
Similar to alkali metals, the reactivity of alkaline earth metals also increases as you move down the group on the periodic table.
- What happens when alkali metals react with water?
Alkali metals react vigorously with water to form hydroxides and hydrogen gas. The general equation for this reaction is 2M(s) + 2H₂O(l) → 2MOH(aq) + H₂(g), where M represents an alkali metal.
- What happens when alkaline earth metals react with water?
Alkaline earth metals react with water to form hydroxides and hydrogen gas, though less vigorously than alkali metals. The general equation for this reaction is M(s) + 2H₂O(l) → M(OH)₂(aq) + H₂(g), where M represents an alkaline earth metal.
- How do alkali metals form ions?
Alkali metals form ions by losing their single valence electron. This results in a cation with a +1 charge.
- How do alkaline earth metals form ions?
Alkaline earth metals form ions by losing their two valence electrons. This results in a cation with a +2 charge.
- What color flames do alkali metals produce in a flame test?
Alkali metals produce different colors in a flame test due to their characteristic emission spectra. For example, lithium produces a red flame, sodium produces a yellow flame, and potassium produces a violet flame.
- What color flames do alkaline earth metals produce in a flame test?
Alkaline earth metals also produce different colors in a flame test. For instance, calcium produces a red-orange flame, strontium produces a red flame, and barium produces a green flame.
- What are some uses of alkali metals?
Alkali metals have various uses. Sodium and potassium are important in biological systems and are used in various industrial processes. Lithium is used in batteries and mood-stabilizing drugs.
- What are some uses of alkaline earth metals?
Alkaline earth metals are also widely used. Magnesium and calcium are important in biological systems. Magnesium is also used in flares and pyrotechnics, while calcium is a key ingredient in cement and plaster.
- Why do alkali metals have low melting points?
Alkali metals have low melting points due to the single valence electron, which results in metallic bonding that is not as strong as in other metals.
- Why do alkaline earth metals have higher melting points than alkali metals?
Alkaline earth metals have higher melting points than alkali metals because they have two valence electrons involved in metallic bonding, resulting in stronger bonds.
- Why are alkali and alkaline earth metals good conductors of electricity?
Both alkali metals and alkaline earth metals are good conductors of electricity because their valence electrons are free to move, which allows them to carry electrical charge.
- How are alkali and alkaline earth metals extracted?
Alkali metals and alkaline earth metals are typically extracted from their ores through electrolysis. For instance, sodium and potassium are extracted from molten salts.
- Why do alkali metals have lower densities than alkaline earth metals?
Alkali metals have lower densities than alkaline earth metals because they have larger atomic radii relative to their atomic masses. This means their atoms are more spread out and thus less dense.
- Why is it dangerous to handle alkali metals and alkaline earth metals?
It is dangerous to handle these metals because of their high reactivity. Alkali metals can react violently with water and even air, while alkaline earth metals, though less reactive, can still cause burns or explosions in certain conditions.
