3.5.4 - Composição do orbital atômico: Número quântico secundário (subcamada ou subnível de energia)

Summary

This video script provides a detailed explanation of quantum numbers, specifically focusing on the secondary quantum number and its significance in atomic structure. It covers the different sublevels of energy (s, p, d, f), their respective shapes, and the relationship between these sublevels and atomic energy levels. The script also highlights the distribution of electrons in orbitals and sublevels, explaining how lower-energy orbitals are filled before higher-energy ones. Additionally, the script touches on the complexity of atomic discovery and how new findings could change our understanding of atomic structure over time.

Takeaways

• 😀 The secondary quantum number, or azimuthal quantum number, determines the shape of an orbital.
• 😀 There are four known sublevels of energy: s, p, d, and f, each corresponding to specific values of the secondary quantum number (0, 1, 2, and 3 respectively).
• 😀 Higher sublevels such as g, h, and i are theoretically possible, but have not yet been observed in naturally occurring elements.
• 😀 Sublevels are associated with orbital shapes, where the 's' orbital is spherical, 'p' is dumbbell-shaped, 'd' has more complex shapes with multiple nodes, and 'f' is even more intricate with multiple nodes.
• 😀 The 's' sublevel is found in all energy levels, while 'p' appears from the second level onward, and 'd' appears from the third level onward.
• 😀 The 'f' sublevel starts appearing from the fourth energy level and continues from there.
• 😀 The energy of an orbital is determined by both the energy level and the sublevel. For example, the 's' sublevel is the least energetic, while the 'f' sublevel is the most energetic.
• 😀 In terms of electron configuration, electrons fill orbitals starting from the lowest energy levels, with the 's' orbitals being filled first.
• 😀 The order of filling orbitals is influenced by energy considerations, with orbitals being filled to minimize energy—sometimes leading to configurations that don't strictly follow a simple sequence, as seen in the Linus Pauling diagram.
• 😀 Understanding the energy differences between orbitals explains why certain electron configurations (e.g., 4s filling before 3d) occur despite the higher number of electrons in some orbitals.

Q & A

What is the secondary quantum number, and what does it represent?

The secondary quantum number (also known as the azimuthal quantum number or angular momentum quantum number) represents the shape of an orbital. It is denoted by 'l' and can take values 0, 1, 2, and 3, corresponding to s, p, d, and f orbitals, respectively.

How is the secondary quantum number related to the orbital's shape?

The secondary quantum number determines the shape of the orbital. For example, an 's' orbital has a spherical shape (l = 0), a 'p' orbital has a dumbbell shape (l = 1), a 'd' orbital has a more complex shape (l = 2), and an 'f' orbital has an even more complex shape (l = 3).

What are the possible sublevels of energy in an atom, and what are their corresponding quantum numbers?

The four possible sublevels of energy in an atom are: s (l = 0), p (l = 1), d (l = 2), and f (l = 3). These sublevels are associated with specific orbital shapes and different energy levels within an atom.

Can an atom have sublevels beyond f?

Although it is theoretically possible for atoms with more than 7 energy levels to have additional sublevels (like g, h, i, etc.), no elements observed so far exhibit sublevels beyond f in their ground state.

Why do we use the term 'sublevel' when discussing quantum numbers?

The term 'sublevel' refers to the different regions within an energy level that electrons occupy. These sublevels (s, p, d, f) differ in shape and energy, and the quantum number 'l' helps classify these sublevels.

Why are the energy levels not always filled in strict order (1s, 2s, 3s, etc.)?

Electrons fill orbitals in a way that minimizes energy. Although lower principal energy levels are filled first, the energy associated with sublevels varies. For example, 4s is filled before 3d because 4s is energetically lower than 3d, despite 3d being in a lower energy level.

What does the Linus Pauling diagram illustrate about electron distribution?

The Linus Pauling diagram shows the sequence in which electrons are filled in orbitals across different energy levels. The diagram reflects the principle that orbitals are filled from the lowest energy sublevel to the highest, even if this results in filling orbitals from higher levels before completing lower levels.

What does it mean that sublevel s is the least energetic, and f is the most energetic?

In terms of energy, the sublevel s is the lowest in energy, followed by p, d, and f. This means that when electrons are distributed, s orbitals are filled first, and f orbitals are filled last because they require the most energy.

What happens when electrons fill higher-energy orbitals before completing lower-energy ones?

This occurs because of the energy relationships between orbitals. For example, the 4s orbital is lower in energy than the 3d orbital, so 4s is filled first. This seemingly non-sequential filling is a result of the system's tendency to minimize energy.

How does the number of energy levels in an atom affect the possible number of sublevels?

The number of sublevels in an atom increases as the number of energy levels increases. For example, an atom with seven energy levels can have sublevels s, p, d, f, g, h, and i, whereas an atom with fewer energy levels would have only some of these sublevels.