Question

What sublevel is being filled in (a) Period 3, Group 3A(13) to \(7 \mathrm{~A}(17)\) ? (b) Period 5, transition elements? (c) the lanthanide series?

Short answer

The sublevels being filled are (a) 3p for Period 3, Group 3A(13) to 7A(17), (b) 4d for Period 5 transition elements, and (c) 4f for the lanthanide series.

Step-by-step solution

Identify the sublevel for Period 3, Group 3A(13) to 7A(17)

In the periodic table, Period 3 elements in Groups 3A to 7A transition from the 3p sublevel starting with aluminum (Group 3A, atomic number 13) and ending with chlorine (Group 7A, atomic number 17). Therefore, the sublevel being filled is the 3p sublevel, as electrons are added to the p-orbitals.

Determine the sublevel for Period 5 transition elements

Period 5 transition elements are located in the d-block of the periodic table. They start filling in from atomic number 39 (yttrium) and end at atomic number 48 (cadmium). This implies that the 4d sublevel is being filled for Period 5 transition elements.

Ascertain the sublevel for the lanthanide series

The lanthanide series comprises elements with atomic numbers 57 through 71. These elements are f-block elements and specifically fill the 4f sublevel. So, the sublevel being filled in the lanthanide series is the 4f sublevel.

Key concepts

Electron Sublevels

Understanding electron sublevels is crucial to grasping the overall layout of the periodic table and the behavior of atoms. Each atom consists of a nucleus surrounded by electrons existing in areas of high probability called orbitals. These orbitals are organized into sublevels, labeled as s, p, d, f (in order of increasing energy and complexity).

The s sublevel has only one orbital, therefore it can hold 2 electrons. The p sublevel has three orbitals, making room for 6 electrons. The d sublevel contains five orbitals, with a capacity for 10 electrons, and the f sublevel has seven orbitals, with enough space for 14 electrons.

• The first two electrons an atom gains fill the s-orbital of the first energy level, forming the 1s sublevel.
• As we continue adding electrons, we move up in energy levels and begin to fill additional s and p sublevels (2s, 2p, 3s, 3p).
• Transition metals fill their d sublevels and begin this process during their 4th period of the periodic table (3d).
• The actinides and lanthanides, located at the bottom of the periodic table, fill f sublevels.

These sublevels conform to the well-known 'aufbau principle' which dictates the order in which sublevels are filled – from lowest to highest energy.

Transition Elements

The transition elements include those found in the d-block of the periodic table and are often referred to as the transition metals. Characterized by their ability to form compounds with a high degree of variability in oxidation states and by the possession of an incomplete d sublevel while in their elemental states or as ions.

Key Properties of Transition Metals:

• They often display several common oxidation states.
• Many have high melting points and form colored compounds.
• They are typically good conductors of heat and electricity.
• These elements tend to have high densities and are usually malleable and ductile.

For the period 5 transition metals, it is the 4d sublevel that is being filled with electrons. Starting with yttrium (Z=39) through to cadmium (Z=48), these transition metals showcase a broad application across various fields such as construction, electronics, and even medicine due to their diverse chemical and physical properties.

Lanthanide Series

The lanthanide series is also known as the rare earth elements comprising fifteen elements from lanthanum (La, atomic number 57) to lutetium (Lu, atomic number 71). These elements are f-block elements, specifically occupying the 4f sublevel in their electron configurations.

Characteristics of Lanthanides:

• Lanthanides have relatively high melting and boiling points.
• They are silvery-white metals that tarnish when exposed to air.
• Many of the lanthanides are typically trivalent, meaning they often form +3 ions.
• They are used in various industries for their magnetic, phosphorescent, and catalytic properties.

Notably, the lanthanides are associated with strong magnetic fields and are essential in the production of high-strength permanent magnets used in modern technologies. During the filling of the 4f sublevel, these elements exhibit very similar chemical properties, which is why they are grouped together despite the gradual increase in atomic numbers.