ChemistryStepByStep
Free chemistry calculators that show their work. Molarity, dilution, stoichiometry, gas laws, pH, and more, with the real formula behind every answer.
Solutions & Concentration
Reactions & Stoichiometry
Atomic & Molecular
Acids & Bases
Reference Charts
Canonical lookup tables -- no numbers to enter, just the standard data.
Free electronegativity chart. Pauling-scale electronegativity values for all 118 elements, with an explanation of what the numbers mean and how to use them to predict bond polarity.
Free amino acid chart. All 20 standard amino acids with their 3-letter and 1-letter codes, side-chain classification, molecular formula, and molecular weight.
Free codon chart. Every mRNA codon in the standard genetic code, mapped to its amino acid, with start and stop codons clearly marked.
Free interactive codon wheel. The standard genetic code as a classic 4-ring radial diagram -- first base, second base, third base, and the resulting amino acid or stop codon.