Other Analogies & Concepts AP Chemistry

Aufbau Principle

Start at lowest energy level

Hund’s Rule

One in each orbital before pairing

Pauli Exclusion Principle

2 electrons per orbital, electrons must have opposite signs

Electron Configuration

1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p⁶6s²4f¹⁴5d¹⁰6p⁶7s²5f¹⁴6d¹⁰7p⁶

Periodic Trends

Atomic Radius: size of an atom (Increases left and down)

Electronegativity: ability to attract an electron (Increases right and up)

Ionization Energy: energy to remove an electron (Increases right and up)

Dipole Moment

Arrow that points towards the more polar side of a molecule (depends on electronegativity and molecular shape)

Electronegativity Difference

Non-Polar: <0.4

Polar: >0.4 & <1.7

Ionic: >1.7

Are Cations or Anions larger in a particle diagram?

Anions, b/c they have more electrons

Properties of Ionic Structures (Salts)

Crystal lattice, hard & brittle, high melting & boiling points, can undergo dissolution, solid at room temperature, good insulators as solid, can only become conductor when dissolved or melted

Dissociation

When water dissolves a salt into two aqueous solutions

Properties of Covalent Bonds

Low melting & boiling points, can be any state of matter, are not conductors, soft solids

Sea of Electrons & Delocalized Electrons

Lattice structures have a sea of electrons around all nuclei, to which we can’t tell which electrons belong to which atoms

Properties of Metallic Bonds

Luster, Malleable, Ductile, conductors, creates oxides, can lose electrons to form cations

Substitutional vs Interstitial Alloys

Substitutional: Atoms in a pure metal are replaced by metals of a similar size

Interstitial: Small atoms are shoved into the spaces between the molecule corners (often non-metals)

Bond Strength

Stability: Strength of the bond via electrons

Bond Length: Distance between the nucleus of the atoms

Bond Energy: Energy required to break the bond,

Solubility Rules

ALWAYS Soluble: SNAP (Sodium, Nitrate, Ammonium, Potassium) + Group 1A (Alkali Metals)