CHEM 1210 Lecture Notes - Lecture 2: Electron Configuration

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3 Feb 2018

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Electronic configuration: the arrangement of electrons in the extra-nuclear space. The energy of electrons in an atom is quantized, which means that an electron in an atom can have only certain allowed energies (represented by electron shells) Ground-state electron configuration: the electron configuration of the lowest energy state of an atom. Each energy level (shell) contains subshells made up of orbitals. An orbital is a region of space that can hold 2 electrons: s, p, d, and f orbitals. Rule 1: orbitals are filled with electrons in the order of increasing energy from lowest to highest. Rule 2: each orbital can hold up to 2 electrons with spins paired. Shell 1: has only an a-orbital and can hold 2 electrons. Shell 2: has an s-orbital and three p-orbitals each with 2 electrons (8 electrons total) Shell 3: has one s-orbital, three p-orbitals, and five d-orbitals. Shell 3: has one s-orbital, three p-orbitals, and five d-orbitals (18 electrons total)

Related Questions

The electron configuration can also be represented by writing the symbol for the occupied subshell and adding a superscript to indicate the number of electrons in that subshell. For example, consider a carbon atom having an atomic number of 6. The total number of electrons in a neutral carbon atom is 6. The electron configuration of the carbon atom represented by the orbital diagram is

This electron configuration can be written as

1s22s22p2

where 1s , 2s , and 2p are the occupied subshells, and the superscript "2" is the number of electrons in each of these subshells.

Use the rules for determining electron configurations to write the electron configuration for Mg .

Express your answer in complete form in order of increasing orbital energy. For example, 1s22s2 should be entered as 1s^22s^2.

CHEM 1430 LIGHT LAB SPRING 2018 A Danish physicist, Neils Bohr, a post-doctoral student in J. J. Thomson's lab and friend of Rutherford, took up the problem of electron arrangement within the atom. Bohr's breakthrough was recognizing Balmer's fixed emission wavelengths, when taken with Planck's Relationship, led to the conclusion the shells, like the radiation emitted, must be quantized (have set, specific energles). Bohr proposed the electrons circulated about the madeus, much like planets cirde surãin seres of concentric shells of increasing size. Each shell stood at a fixed (set) distance from the nucleus with the shell nearest the nucleus taking the m and a shell further away taking the n in the B-R equation. The integral values of m and n taken with the discrete wavelength led Bohr to propose the shells were "quantized," meaning electrons could only exist at the surface of the shells. When an electron moved from a high shell, n, to a low shell, m, light of a foxed wavelength was emitted Bohr reasoned the shells were special due to this quantized nature. An electron in a shell occupied what Bohr described as a "steady state," meaning the electron could circulate about the nucleus without loss or gain of energy. This steady state proposition, which conflicted with classical physics, could not be explained by then available data but was required for Bohr's proposed structure to be stable. Later work revealed the wave-particle duality of the electron which lead to acceptance of the Steady State Proposition. The energy of an electron in any shell, represented by n, can be calculated using an equation derived from combining the Balmer-Rydberg and Planck equations. The energy of an electron in the no shell is given by é¦¯.h RL where hcR,-2.18x10-*) where Ru, is the Rydberg's Constant for the hydrogen atom, h is Planck's Constant and c is the speed of light NOTE: The energy is given a nexative value to refect the stabillting, attractive force between the negatively charged electron and the positively charged nucleus. As the shell number n increases, the attractive force decreases leading to a rising shell energies (E, increases, values less negative). ACTIVITY Calculate the energles for an electron in the first 7 shells of the hydrogen atom using the above relationship, recording the values in the center column of the Hydrogen the right-hand column in the table, convert the shell with the exponent of 10 Improper sclentific notation is typically used to plot data covering several orders of magnitude (powers of ten). Shell Energy Table. For energies to improper scientific notation Hydrogen Shell Energy Table Shell Value, n Calculated Shell Energy.ã Express Shell Energy in improper Scientific Notation, x 10-1 Page 9 of 12

Sort the following electron configurations of neutral atoms based on whether they represent an excited state configuration or a ground state configuration.

CHEM 1210 Lecture Notes - Lecture 2: Electron Configuration

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