Question

1. What orbital sublevel starts to fill after the completion of the 4d sublevel?

2. What orbital sublevels are being filled by the valence electrons of silicon?

3. How many 4p electrons are there in tin?

4. What is the electronic configuration of chromium?

5. Which is the electronic configuration of K+?

6. The electronic configuration of O2- has the configuration of which noble gas?

7. Which atom is larger, calcium, bromine or gallium?

8. Which atom is larger, phosphorus, nitrogen or arsenic?

9. Which ion is larger, Cl-, I- or Br-?

10. Which atom has a highest ionization energy, germanium, selenium or arsenic?

Answer 1

1. According to the Aufbau principle, the available atomic orbitals with the lowest energy levels are occupied before those with higher energy levels. The increasing energy levels of atomic orbitals are determined from the diagonal rule as:

Therefore, after the completion of 4d sublevels, 5p orbital starts to fill.

2. The atomic number of Silicon is 14. There are four electrons in the valence shell(n=3) of silicon. The electronic configuration of Silicon is: 1s²2s²2p⁶3s²3p²

Therefore, the valence electrons of silicon fill 3s and 3b orbitals.

3. The atomic number of Tin is 50.Tin has a ground-state electron configuration of 1s ²2s ²2p ⁶3s ²3p ⁶4s ²3d ¹⁰4p ⁶5s ²4d ¹⁰5p ^2.

Therefore, there are six 4p electrons in Tin.

4. The atomic number of Chromium is 24. The electron configuration for chromium is

1s²2s²2p⁶3s²3p⁶3d⁵4s¹ . The 4s orbital has only one electron because of the stability of half-filled 3d orbital.

5. The atomic number of potassium( K) is 19. For K⁺ ion, the number of electrons is 18 and it has the following electronic configuration:

1s²2s²2p⁶3s²3p⁶

6. The atomic number of Oxygen is 8. The configuration for neutral O atom is:

1s²2s²2p⁴

When oxygen gains two electrons, it acquires a charge of 2−. Therefore, the two electrons, which go into the highest-energy atomic orbitals, give you a new configuration of

1s²2s²2p⁶

for O^2-, which is the same electron configuration as Ne.

7. Among Calcium, Gallium, and Bromine, the atom of Calcium is larger. This is because moving from left to right across a period, the atomic radius decreases. The nucleus of the atom gains protons moving from left to right, increasing the positive charge of the nucleus and increasing the attractive force of the nucleus upon the electrons.

8. The atom of Arsenic is larger among Phosphorus, Nitrogen, and Arsenic. This is because the number of energy levels increases as you move down a group as the number of electrons increases. Each subsequent energy level is further from the nucleus than the last. Therefore, the atomic radius increases down the group.

9. The ion of Iodine (I^-) is larger than that of Bromine and Chlorine. This is because as we move down the group, the energy level increases and so does the ionic radii.

10. Selenium atom has the highest ionization energy among Germanium, Selenium or Arsenic. This is because the nucleus of the atom gains protons moving from left to right, increasing the positive charge of the nucleus and increasing the attractive force of the nucleus upon the electrons. Therefore, it will be more difficult to remove an electron from the valence shell of Selenium because of the strongest positive nuclear charge.