Write the condensed electron configurations for the following atoms, using the appropriate noble-gas core abbreviations: (a) Cs, (b) Ni, (c) Se, (d) Cd, (e) U, (f) Pb.

Verified step by step guidance

1. Step 1: Identify the atomic number of each element to determine the total number of electrons. For example, Cs has an atomic number of 55, Ni is 28, Se is 34, Cd is 48, U is 92, and Pb is 82.
2. Step 2: Determine the noble gas that precedes each element in the periodic table. This noble gas will be used as the core for the electron configuration. For instance, the noble gas preceding Cs is Xe, for Ni it is Ar, for Se it is Ar, for Cd it is Kr, for U it is Rn, and for Pb it is Xe.
3. Step 3: Write the electron configuration starting with the noble gas core. For example, for Cs, start with [Xe], and then add the remaining electrons in the appropriate orbitals.
4. Step 4: Fill the orbitals following the Aufbau principle, which states that electrons fill orbitals starting from the lowest energy level to the highest. Use the order of filling: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p.
5. Step 5: Ensure that the total number of electrons in the configuration matches the atomic number of the element. Adjust the configuration if necessary to account for any exceptions to the typical filling order, such as those seen in transition metals or lanthanides and actinides.

Key Concepts

Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals. It is represented by a series of numbers and letters that indicate the energy levels and sublevels occupied by electrons. Understanding electron configurations is essential for predicting an element's chemical properties and behavior in reactions.

Noble Gas Core

The noble gas core refers to the electron configuration of the nearest noble gas that precedes an element in the periodic table. This shorthand notation simplifies the representation of electron configurations by indicating that the inner electrons are the same as those of the noble gas, allowing for a more concise expression of the outer, valence electrons.

Periodic Table Trends

Periodic table trends, such as atomic size, ionization energy, and electronegativity, are essential for understanding how electron configurations influence an element's reactivity and bonding. These trends arise from the arrangement of electrons and the effective nuclear charge experienced by outer electrons, which can help predict the behavior of elements in chemical reactions.