The bench · nothing leaves your browser
Five instruments for the work you were probably about to do by hand. No account, no upload, no waiting — every calculation runs locally against the same 118-element dataset the rest of the site uses.
Tool 01
Nested brackets, hydrate dots and ionic charges all parse. Try Ca(OH)2, CuSO4·5H2O or Fe2(SO4)3.
Tool 02
Solved as a linear system over exact fractions, not by trial and error — so redox equations that resist inspection come out in one step.
Tool 03
Fill the subshells in the right order. The Aufbau diagonal is drawn beside you until you no longer need it.
— click subshells below —
Tool 04
Pick up to four. Every bar is scaled against all 118, so you can see at a glance which is the outlier.
Tool 05
The units chemistry keeps switching between — temperature, energy, pressure, amount and atomic-scale length.
About these tools
Every element in the formula contributes its standard atomic weight multiplied by how many atoms of it appear. Those weights are averages across each element's natural isotope mix, which is why they are rarely whole numbers — chlorine is 35.45 because roughly three quarters of natural chlorine is Cl-35 and one quarter Cl-37. Percentage composition is each element's total contribution divided by the whole.
Conservation of each element becomes one linear equation: the total atoms of that element on the left must equal the total on the right. Stack those into a matrix, reduce it to row-echelon form using exact fractions rather than floating point, and read off the null-space vector — that vector is the set of coefficients. Clearing denominators and dividing by the greatest common divisor gives the smallest whole numbers. It never guesses, so it handles redox equations like permanganate and hydrochloric acid in the same single step as burning hydrogen.
Because energy, not shell number, decides the order. The Madelung rule says subshells fill by increasing n + l: 4s has n+l = 4, while 3d has n+l = 5, so 4s wins. Once electrons are actually in the atom the picture inverts — in a neutral transition metal 3d sits below 4s, which is why ions like Fe²⁺ lose their 4s electrons first, not their 3d ones. Chromium and copper break the pattern outright, taking a half-full or full d shell over a full s shell.
No. Every calculation on this page runs in your browser. The only network request is the one that fetched the element data when the page loaded, and it is cached for the rest of your session. Nothing you type is transmitted or stored.