Question

Refer to the periodic table and state the highest energy sublevel for each of the following elements: (a) He (b) \(K\) (c) U (d) \(\mathrm{Pd}\) (e) Be (f) Co (g) Si (h) \(\mathrm{Pt}\)

Short answer

(a) 1s, (b) 4s, (c) 5f, (d) 4d, (e) 2s, (f) 3d, (g) 3p, (h) 5d.

Step-by-step solution

Electron Configuration Review

To determine the highest energy sublevel for an element, we first need to understand the electron configuration, which helps in observing the filling order of orbitals and sublevels. Recall that electrons fill atomic orbitals in the order of increasing energy levels.

Determine Highest Sublevel for He

Helium has two electrons. Its electron configuration is 1s², thus the highest energy sublevel is 1s.

Determine Highest Sublevel for K

Potassium (K) is element number 19. Its electron configuration is [Ar] 4s¹, so the highest energy sublevel is 4s.

Determine Highest Sublevel for U

Uranium (U) is element number 92. Its electron configuration is [Rn] 5f³ 6d¹ 7s². The highest energy sublevel is 5f.

Determine Highest Sublevel for Pd

Palladium (Pd) is element number 46. Its electron configuration is [Kr] 4d¹⁰, so the highest energy sublevel is 4d.

Determine Highest Sublevel for Be

Beryllium (Be) has 4 electrons. Its electron configuration is 1s² 2s². The highest energy sublevel is 2s.

Determine Highest Sublevel for Co

Cobalt (Co) is element number 27. Its electron configuration is [Ar] 3d⁷ 4s², so the highest energy sublevel is 3d.

Determine Highest Sublevel for Si

Silicon (Si) is element number 14. Its electron configuration is [Ne] 3s² 3p², making the highest energy sublevel 3p.

Determine Highest Sublevel for Pt

Platinum (Pt) is element number 78. Its electron configuration is [Xe] 4f¹⁴ 5d⁹ 6s¹, so the highest energy sublevel is 5d.

Key concepts

Electron Configuration

Electron configuration is a method used to describe the arrangement of electrons in an atom's energy levels, or shells. Each electron in an atom is assigned to an atomic orbital, which is a region of space where there is a high probability of finding an electron. Understanding electron configurations helps us predict chemical properties and behavior.

When we write electron configurations, we start from the lowest energy level and fill the orbitals in order of increasing energy. For example, the electron configuration for Helium is 1s², indicating that both electrons occupy the s sublevel of the first energy level.

• The notation is comprised of a series of numbers and letters.
• Numbers denote the principal energy levels (1, 2, 3, etc.).
• Letters indicate the type of orbital (s, p, d, f).
• Superscript numbers show the number of electrons in those orbitals.

This systematic way of representing electrons in atoms helps us grasp the importance of electron arrangement in chemical reactions.

Sublevels

Sublevels are subdivisions of electron shells (energy levels) in an atom. Each shell has a certain number of sublevels that increase as you go to higher shells. The names of these sublevels are s, p, d, and f:

• s sublevel: The simplest sublevel that can hold a maximum of 2 electrons.
• p sublevel: Has three orbitals and can hold up to 6 electrons.
• d sublevel: Contains five orbitals, accommodating up to 10 electrons.
• f sublevel: The most complex, including seven orbitals for a total of 14 electrons.

Each type of sublevel corresponds to a different shape of the atomic orbital, which influences how electrons are distributed and interact with other atoms.

For instance, Silicon (#14) has an electron configuration of [Ne] 3s² 3p². Here, the highest energy sublevel occupied by electrons is the 3p.

Atomic Orbitals

Atomic orbitals are regions where an electron is most likely to be found around an atom's nucleus.

The concept of orbitals comes from quantum mechanics. Unlike the circular orbits you might imagine from planetary models, atomic orbitals are better visualized as clouds of probability. Each type of sublevel has a distinct orbital shape:

• s orbitals are spherical.
• p orbitals are dumbbell-shaped.
• d orbitals have more complex shapes that often resemble a four-lobed clover.
• f orbitals are even more intricate in geometry.

In the context of chemistry, these shapes help determine the kinds of chemical bonds an atom can form. For Palladium (Pd, #46), the electron configuration [Kr] 4d¹⁰ signifies that the 4d orbitals contain electrons, indicating their role in bonding and other atomic interactions.

Electron Filling Order

Electron filling order describes the sequence in which atomic orbitals are filled with electrons, following a specific pattern known as the Aufbau principle. This principle suggests that electrons fill lower-energy orbitals before higher-energy ones, revealing not only the chemical stability of elements but also guiding predictions for chemical reactivity.

General filling order is dictated by increasing energy levels, illustrated by this pattern: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, and so on.

• This sequence can be remembered using the periodic table's layout, as it often follows the table's progression from left to right.
• The actual filling order might seem to jump across periods due to energy overlaps, such as 4s being filled before 3d.

Looking at Potassium (K, #19), we observe [Ar] 4s¹ as its electron configuration, which highlights the 4s orbital being filled after the 3p orbitals. This accounts for its specific placement in the periodic table and its chemical characteristics.