Maahi's Chemistry Connections

Measurement and Data Processing

Lab Equipment

Graphing Techniques

Significant Figures: the number of digits reflecting the precision of a given measurement

Scientific Notation: used to make numbers and quantities easier to comprehend and write

Precision

Random Errors: Uncontrolled variables in an experiment

Accuracy

Systematic Errors: Flaw in the actual experimental design, defect with instrument or the way the measurement was taken

Stoichiometry Relationships

Mole Concept

Mole (mol)

n=N/L

n=m/M

Molar Mass (g/mol)

M=m/n

Avogadro's Constant 6.02×10²³ objects/mol⁻¹

Limiting Reactant: the first reactant to be consumed completely in a chemical reaction

Excess Reactant: the reactant that could keep reacting if limiting reactant had not been done

Titrations: technique where solutions of known concentration is used to determine concentration of unknown solution (n=CV)

Isotopes: atoms of the same element with different mass numbers, but similar chemical properties

Atomic Structure

Electron Configuration

Ionization energy: minimum energy required to remove an electron from a neutral gaseous atom/moleule in its ground state
x^(n-1)(g) → x^n+(g) + e⁻

Orbital

Hund's Rule: orbitals of same sublevel are filled singly, then paired up

Aufbau Principle: electrons are added to lowest energy level first

Pauli Exclusion Principle: no more than two electrons per orbital and they must spin oppositely

Each orbital has a specific energy level, with 1s being the lowest energy level

Standard Notation

Periodicity

Periodic Trends

Ionization Energy/ Electron Affinity

Decreases down a group/ Increases across a period

Atomic Radius

Increases down a group/ Decreases across a period

Electronegativity

Decreases down a group/ Increases across a period

Melting and Boiling Point

Decreases down a group/ Increases across a period until group 14 and then decreases

Metals

lose electrons in reactions (cations)

Non-Metals

gain electrons in reactions (anions)

Chemical Bonding and Structure

Hybridization

formed when two atomic orbitals, each containing one electron, overlap to from a new combined orbital

Molecular Polarity

Intermolecular Forces

forces that exist between molecules
London Dispersion Forces → all molecules(polar/nonpolar)
Dipole-Dipole/Hydrogen Bonding → polar

partial charge distribution of atoms in a compound is uneven which is dependent on individual molecular geometry and symmetry

Ionic Bonding

metals and nonmetals (ΔEN ≥ 1.8)

Covalent Structures

nonmetals (0 ≤ ΔEN ≥ 1.7)

Bond Length

measure of the distance between two bonded nuclei

Bond Strength

measure of energy required to break bond

Thermochemistry

Standard Enthalpy Change

Neutralization

enthalpy change when a strong acid and base react together to form one mole of water under standard conditions

1. Calculate the number of moles of acid and base using n=cv

2. Determine the limiting reactant

3. Add the volumes of acid and base together (where 1cm^3=1g) to get the mass

4. Use Q=mc∆T to calculate enthalpy change

5. Use ∆H=Q/n

Chemical reactions that involve transfer of heat between system and surroundings

Exothermic

More heat energy is released than what is added

Bond making

Endothermic

Bond breaking

More heat energy is added than what is released