NPCIL Trainee Chemistry — practice by topic

1. The periodic table can be divided into blocks according to which orbital type is being filled with the last electron. 2. The text states: "The representative elements are elements where the s and p orbitals are filling." 3. Transition elements instead have d orbitals filling, and inner transition elements have f orbitals filling. 4. So elements filling s and p orbitals are, by definition, the representative elements. _Source: OpenStax Chemistry Ch 18 "Representative Metals, Metalloids, and Nonmetals", p.964 §18.1 Periodicity_

1. Alkali metals (group 1) are unusually soft and light compared to most other metals. 2. The text states: "lithium...has the lowest density of any metal (0.5 g/cm3)." 3. This is why lithium famously floats even on paraffin oil, which is itself a low-density liquid. 4. So among the alkali metals -- and among all metals -- lithium has the lowest density. _Source: OpenStax Chemistry Ch 18 "Representative Metals, Metalloids, and Nonmetals", p.966 §18.1 Periodicity_

1. Alkali metals are strong reducing agents that readily give up their single valence electron. 2. The text states: "The alkali metals all react vigorously with water to form hydrogen gas and a basic solution of the metal hydroxide." 3. For example, lithium reacts with water as 2Li(s) + 2H2O(l) → 2LiOH(aq) + H2(g), producing lithium hydroxide and hydrogen gas. 4. There is no chlorine present to form a chloride, and no oxygen gas or peroxide forms in this particular reaction. 5. So the products of an alkali metal reacting with water are hydrogen gas and the metal hydroxide. _Source: OpenStax Chemistry Ch 18 "Representative Metals, Metalloids, and Nonmetals", p.966 §18.1 Periodicity_