Periodic Table: Trends and Configurations

• Elements are grouped by chemical properties on the periodic table.
• Groups and periods are concepts used to organize elements on the periodic table.

Periodic Trends

• Atomic Radius refers to the size of an atom, typically decreasing across a period and increasing down a group.
• First Ionization Energy is the energy required to remove an electron from an atom.
• Electron Affinity is the energy change when an electron is added to a neutral atom.

Electron Configurations

• Electron configurations involve orbital shapes, energy shells, and subshells.
• Electron configurations can be written using the Aufbau principle and Hund's rule.
• Orbital diagrams visually represent electron configurations.
• Magnetism includes paramagnetism, which is the attraction to a magnetic field due to unpaired electrons, and diamagnetism, which is the repulsion from a magnetic field due to paired electrons.

Relationship Between Ionization Energy and Atomic Radius

• First ionization energy and atomic radius are inversely related.
• Large atoms tend to have low first ionization energies.

Inert Noble Gases

• Noble gases are inert due to their full valence shells and high ionization energies.

Reactive Alkali Metals

• Alkali metals are reactive because they have low ionization energies and readily lose their outermost electron.
• They also have very low electron affinities meaning that they don't bind their electrons easily and donate them to other materials easily.

Expected Charges of Atoms

• Br commonly forms a -1 charge.
• Mg commonly forms a +2 charge.
• O commonly forms a -2 charge.

Electron Configurations

• Na - 1s²2s²2p⁶3s¹ or [Ne]3s¹
• Br [Ar]4s²3d¹⁰3p⁵
• Ti [Ar]4s²3d²
• F [He]2s²2p⁵

Unpaired Electrons

• Sodium, Titanium, Bromine, Fluorine have unpaired electrons (refer to the orbital diagrams).

Correcting Orbital Diagrams

• In orbital diagrams, orbitals must have the same spin when singly occupied.
• Diagram C is wrong because the orbital needs to have the same spin orientation when they are singly occupied.

Core and Valence Electrons

• 1s²2s²2p³ has 5 valence electrons and 2 core electrons.
• 1s²2s²2p⁶3s¹ has 1 valence electron and 10 core electrons.
• 1s²2s²2p⁶3s²3p⁶4s² has 2 valence electrons and 18 core electrons.

Excited State

• Excited state is when electrons occupy higher energy orbitals before filling up the lower energy orbitals, often associated with colors and light release.
• A neon atom in a neon sign represents an excited state.
• An oxygen molecule in the liquid state at low temperature is in the ground state.
• An iron atom sparking in a blacksmith's forge represents an excited state.

Ranking Atoms by Size and Ionization Energy

• For Li, B, F, O, the order of increasing size is F < O < B < Li.
• For Cs, N, Cr, H, the order of increasing size is H < N < Cr < Cs.
• Chlorine has the greatest first ionization energy among Na, Mg, S, Cl.
• Helium has the greatest first ionization energy among Cs, Ti, Al, O, He.

Magnetic Properties

• Metals with unpaired electrons are attracted to a magnetic field.
• Iron and Cesium would attract a magnetic field but calcium would repel a magnetic field.

Reactivity Experiment

• Use three different metals to test the reactivity to oxygen (oxygen is a powerful electron acceptor).
• Colors or weight changes for observation.
• Use simultaneous timing, temperature, and consistent particle size of the metals as controls.
• Metal serves as the independent variable, and time serves as the dependent variable.