# Chemistry 11 reference sheet

## Measurement and amount
- N=nN_A, where N_A=6.02214076times10^23,mathrmmol^-1
- n=m/M
- c=n/V with V in litres
- Ideal dilution: c_1V_1=c_2V_2

## Atomic structure and bonding
- Electron count for an ion: N_e=Z-q when q is the signed ionic charge in elementary-charge units
- Formal charge bookkeeping: FC=V-N-tfrac12B
- Bond polarity evidence: Deltachi=|chi_A-chi_B|
- Molecular polarity requires vector addition of bond dipoles and geometry.

## Reaction and energy
- Balance atoms and charge before using coefficient ratios.
- Stoichiometry path: given quantity to moles to mole ratio to requested quantity.
- Delta H=H_products-H_reactants
- Approximate bond-energy estimate: Delta Happroxsum E_broken-sum E_formed

## Solutions
- Dissociation equations conserve atoms and charge.
- Mixed-ion problems: convert each contribution to moles, apply dissociation/reaction stoichiometry, divide remaining moles by final volume.

## Quality checks
Carry units, retain guard digits, report justified significant figures, preserve raw data, distinguish random scatter from systematic error, and qualify conclusions by model domain and evidence quality.
