IBSL Chemistry Topic 3 Periodicity Multiple Choice Questions

The periodic table is arranged in order of increasing atomic number because the atomic number represents the number of protons in an atom's nucleus. Since each element has a unique number of protons, arranging the elements by atomic number ensures that they are organized in a logical and consistent manner. This arrangement also helps to group elements with similar properties together, making it easier to study and understand the trends and patterns in the periodic table.

The correct answer is Be (Beryllium). In the periodic table, the group number represents the number of valence electrons in an element's outermost energy level, while the period number represents the number of energy levels an element's electrons occupy. Beryllium is located in group 2 and period 2, meaning it has 2 valence electrons and its electrons occupy 2 energy levels, making the group number and period number the same for Beryllium.

The properties of nuclear charge and electronegativity increase from sodium to argon. Nuclear charge increases because there are more protons in the nucleus as you move across Period 3. Electronegativity increases because there are more protons attracting the electrons in the outer shell, making the atom more likely to attract electrons in a chemical bond. Atomic radius, on the other hand, decreases from sodium to argon because the increased nuclear charge pulls the electrons closer to the nucleus, making the atom smaller.

Strontium is an element in Group 2 of the Periodic Table with atomic number 38. Its atomic radius is larger than that of magnesium. The atomic radius generally increases down a group in the periodic table, so strontium, being below magnesium in Group 2, would have a larger atomic radius.

In this question, the elements Li, K, Br, and Cl are being compared to determine which pair reacts most readily. Reactivity is determined by the tendency of an element to gain or lose electrons. In general, alkali metals (such as Li and K) have a strong tendency to lose electrons, while halogens (such as Br and Cl) have a strong tendency to gain electrons. Among the given pairs, K + Cl2 is the most reactive because K readily loses one electron to form K+ ion, while Cl readily accepts one electron to form Cl- ion. This transfer of electrons between K and Cl is a highly exothermic reaction, making K + Cl2 the most reactive pair.

As the atomic number increases for both alkali metals and halogens, the number of electrons and protons in the nucleus also increases. This leads to an increase in the size of the atom, resulting in an increase in atomic radii. Therefore, the property that increases with increasing atomic number for both alkali metals and halogens is atomic radii.

Ge (Germanium) is the correct answer because it is located directly below Carbon (C) in the periodic table, which is the element with 14 electrons. Ge has similar chemical properties to C due to its similar electron configuration and can form similar compounds.

Potassium (K) is more reactive than sodium (Na) because it is located higher in the periodic table. Chlorine (Cl2) is a highly reactive element. Therefore, the reaction between K(s) and Cl2(g) is expected to be the most vigorous because it involves the most reactive metal (K) and a highly reactive non-metal (Cl2). The other reactions involve either a less reactive metal (Na) or a less reactive non-metal (Br2), so they would be expected to have less vigorous reactions.

The first ionization energy is the energy required to remove one electron from an atom. As we move across a period in the periodic table, the atomic radius decreases and the effective nuclear charge increases. This means that it becomes more difficult to remove an electron, resulting in a higher ionization energy. Oxygen has a higher ionization energy than fluorine because oxygen is to the right of fluorine in the periodic table. Neon has the highest ionization energy because it is a noble gas and has a full valence shell, making it very stable. Therefore, the correct order of increasing first ionization energies is oxygen, fluorine, neon.

SO3(g) will produce the most acidic solution because it reacts with water to form sulfuric acid (H2SO4), which is a strong acid. Al2O3(s) and SiO2(s) are amphoteric oxides, meaning they can react with both acids and bases, but they do not produce strong acids. Na2O(s) reacts with water to form sodium hydroxide (NaOH), which is a strong base, not an acid. Therefore, SO3(g) is the only option that will produce a strong acid when added to water, making it the most acidic solution.

Na (sodium) has the lowest first ionization energy among the given elements. Ionization energy refers to the energy required to remove an electron from an atom. Sodium has a larger atomic radius compared to lithium, magnesium, and aluminum. As a result, the outermost electron in sodium is further away from the nucleus and experiences less attraction. This makes it easier to remove the electron from sodium, requiring less energy compared to the other elements.

The given answer "I only" suggests that only reaction I occurs as written. This means that reaction II does not occur as written.

Cl2 will oxidize I- (aq) because chlorine is a stronger oxidizing agent compared to iodine. This means that chlorine is more likely to gain electrons and be reduced, while iodine is more likely to lose electrons and be oxidized. Therefore, when Cl2 reacts with I- (aq), Cl2 will gain electrons from I- and I- will be oxidized to I2.