Question 1: What are alkali metals?
Solution: Alkali metals are elements located in Group 1 of the periodic table. They include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). They are highly reactive, have one electron in their outermost shell, and readily lose that electron to form a +1 cation.
Question 2: What are alkaline earth metals?
Solution: 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 reactive (though less so than alkali metals), and typically form +2 cations.
Question 3: How do alkali metals react with water?
Solution: Alkali metals react with water to form a basic hydroxide and hydrogen gas. For example, the reaction of sodium with water can be represented as 2Na + 2H₂O → 2NaOH + H₂↑.
Question 4: What happens when alkaline earth metals react with oxygen?
Solution: When alkaline earth metals react with oxygen, they form a metal oxide. For example, calcium reacts with oxygen to form calcium oxide: 2Ca + O₂ → 2CaO.
Question 5: What is the lightest alkali metal?
Solution: The lightest alkali metal is lithium (Li), with an atomic number of 3 and an atomic mass of approximately 6.94.
Question 6: Which alkali metal is the most reactive?
Solution: Cesium (Cs) is the most reactive of the alkali metals. Its reactivity increases down the group as the atomic size increases.
Question 7: What is the heaviest alkaline earth metal?
Solution: The heaviest alkaline earth metal is radium (Ra), with an atomic number of 88.
Question 8: Which alkaline earth metal is the most reactive?
Solution: The reactivity of the alkaline earth metals increases down the group. Therefore, radium (Ra) is the most reactive of the alkaline earth metals.
Question 9: What is the oxidation state of alkali metals?
Solution: Alkali metals typically have an oxidation state of +1. They lose one electron from their outermost energy level to achieve a stable electron configuration.
Question 10: What is the oxidation state of alkaline earth metals?
Solution: Alkaline earth metals typically have an oxidation state of +2. They lose two electrons from their outermost energy level to achieve a stable electron configuration.
Question 11: Are alkali metals and alkaline earth metals metals, nonmetals, or metalloids?
Solution: Both alkali metals and alkaline earth metals are metals. They exhibit properties typical of metals, such as malleability, ductility, and high electrical and thermal conductivity.
Question 12: What happens when alkaline earth metals react with water?
Solution: Alkaline earth metals react with water to produce a metal hydroxide and hydrogen gas. However, the reactivity is less vigorous compared to alkali metals. For example, magnesium reacts with steam to produce magnesium hydroxide and hydrogen: Mg + 2H₂O → Mg(OH)₂ + H₂↑.
Question 13: How are alkali metals stored and why?
Solution: Alkali metals are stored in mineral oil or kerosene. They are stored this way because they are highly reactive and can react with moisture in the air or with oxygen, which can be dangerous.
Question 14: How many valence electrons do alkali metals and alkaline earth metals have?
Solution: Alkali metals have one valence electron, while alkaline earth metals have two valence electrons.
Question 15: Which element is the only radioactive alkaline earth metal?
Solution: Radium (Ra) is the only radioactive alkaline earth metal.
Question 16: Which alkali metal is kept under nitrogen?
Solution: Sodium (Na) is often stored under nitrogen to prevent it from reacting with oxygen or moisture in the air.
Question 17: What is the first ionization energy and how does it change across the period and down the group for alkali metals and alkaline earth metals?
Solution: The first ionization energy is the energy required to remove one electron from a neutral atom to form a positive ion. For both alkali and alkaline earth metals, ionization energy generally decreases down a group due to the increasing atomic size. Across a period from left to right, ionization energy increases due to increasing nuclear charge with no significant increase in shielding effect.
Question 18: How do alkali metals react with halogens?
Solution: Alkali metals react vigorously with halogens to form salts. For example, sodium reacts with chlorine to form sodium chloride: 2Na + Cl₂ → 2NaCl.
Question 19: What type of bonds do alkali metals and alkaline earth metals typically form?
Solution: Alkali metals and alkaline earth metals typically form ionic bonds with nonmetals, where the metal atoms lose one or two electrons (respectively) to form positive ions.
Question 20: What is the trend in melting points for alkali metals and alkaline earth metals?
Solution: For alkali metals, the melting point decreases down the group as the metallic bonding weakens with increasing atomic size. For alkaline earth metals, there is no clear trend – the melting points of beryllium and magnesium are high because of their small size, and the other elements have relatively low melting points.
