Question

Select all the true statements.

a. Ionic bonding is more prevalent for the higher oxidation states and covalent bonding is more prevalent for the lower states.
b. The highest oxidation state of elements in Groups 3A through 7B is +3.
c. In the transition series, atomic size across a period decreases at first but then remains relatively constant.
d. The transition elements in a period show a steady increase in electronegativity.

Answer 1

The true statements are 'a' regarding ionic and covalent bonding tendencies with oxidation states, and 'c' concerning the atomic size trend across the transition series.

The false statements are 'b', as the highest oxidation state is not always +3, and 'd', with electronegativity not steadily increasing across a period for transition metals.

Step-by-step explanation:

The correct statements out of the given options are:

• a. Ionic bonding is more prevalent for the higher oxidation states, and covalent bonding is more prevalent for the lower oxidation states. This is true as transition metals in low oxidation states have lower electronegativity values than oxygen, resulting in more ionic oxides. Conversely, transition metals in higher oxidation states have electronegativity values close to that of oxygen, which gives more covalent character to the oxides.
• c. In the transition series, atomic size across a period initially decreases but then remains relatively constant because of the increasing number of electrons, which increases electronegativity and attracts outer electrons more strongly, effectively counteracting the increase in atomic number. However, additional electron-electron repulsion within the d-orbitals eventually leads to a stabilization in the atomic size.

The false statements are:

• b. The highest oxidation state of elements in Groups 3A through 7B is not universally +3. Some of these elements can achieve higher oxidation states, especially the heavier transition metals, which often exhibit oxidation states greater than +3.
• d. The transition elements in a period do not show a steady increase in electronegativity. There is a general trend of increasing electronegativity across a period, but the variation is not always steady because of the complex electronic configurations of transition metals.

Answer 2

In the transition series, atomic size across a period decreases at first but then remains relatively constant.

The transition elements in a period show a steady increase in electronegativity.

Step-by-step explanation:

In considering the transition series, we observe that atomic sizes of the elements decreases first and subsequently remain constant. The reason for the initial decrease in atomic size is the increase in nuclear charge across the period. After the first few elements in the period, the atomic size remains relatively constant due to shielding effect of the inner d electrons which opposes the increase in effective nuclear charge.

It is also observed that electro negativity increases smoothly across the period for the transition series. Consequently, the transition series become less electro positive across the period.