3.3-3.5 Electron Configurations and Orbital Diagrams, Paramagnetism/Diamagnetism

valence electrons

for Main Group Elements**, the electrons in the outermost principal energy level (the highest value of n)

valence electron purpose

important fact for how an atom behaves chemically and physically, and responsible for chemical bonding

core electrons

inner electrons in complete principal energy levels

core electrons purpose

responsible for shielding effects but NOT responsible for bonding

Main Group Number (1A-8A)

How many Valence electrons an atom has (Letter Number on top of the column)

for 1A, 2A, and aluminum, group number gives charge of _____ (lose valence electrons)

cations (Na in 1A —> Na+)

for 7A, 6A, and 5A, their charge is calculated by Group Number - 8 and therefore gives charge of _____ (gain valence electrons)

anions (O in 6A —> 6-8 = -2 so it becomes O2-)

period number/principal quantum number

the principal energy level of the valence electrons (The row number (period) tells you the highest energy level (𝑛) where those valence electrons live)

exception to the Aufbau principle

Normally, you fill the 𝑠-orbital completely before putting any electrons into the 𝑑-orbital. However, elements like Chromium (Cr), Copper (Cu), Molybdenum (Mo), and Silver (Ag) steal one electron from their outer 𝑠-orbital to optimize their 𝑑-orbital

irregular configurations to know

Cr: [Ar] 4s¹ 3d⁵
Cu: [Ar] 4s¹ 3d¹⁰
Mo: [Kr] 5s¹ 4d⁵
Ag: [Kr] 5s¹ 4d⁵
(1s is given to d)

electron configuration of ions writing process

1. write electron configuration of the neutral parent atom

2. Add or remove electrons depending on the charge:

   1. Anions (Negative charges): Add electrons to the lowest empty spot available.

   2. Cations (Positive charges): Remove electrons from the outermost shell (the highest shell number, 𝑛)

elements gain or lose electrons to match the electron count of the nearest ____ __ (Group 8A)

noble gas

what do metals form?

cations (lose electrons)

what do nonmetals form?

anions (add electrons)

paramagnetism

The atom or ion is attracted by an external magnetic field. This property arises because it contains unpaired electrons (single arrows alone in a box)

diamagnetism

The atom or ion is slightly repelled by an external magnetic field. This property occurs because all electrons are paired up (every box has two opposing arrows, or is completely empty).

principal quantum number for d-electrons reminder

period/row number - 1

alkali metal, alkaline earth metal, halogen, and noble gas periodic table

spdf orbital diagrams reminder