Interactive periodic table
Click any element to see its atomic mass, electron configuration, electronegativity, melting and boiling points and more. Switch to 'State at a temperature' to watch elements melt and boil, and use the molar mass calculator for any formula, with the working shown.
Hydrogen
Nonmetal
- Relative atomic mass
- 1.008
- Group / period / block
- 1 / 1 / s
- Electron configuration
- 1s1
- Electronegativity (Pauling)
- 2.2
- State at room temperature
- Gas
- Melting point
- -259.3 °C (13.8 K)
- Boiling point
- -252.9 °C (20.3 K)
- Density
- 0.00009 g/cm³
- Atomic radius
- 120 pm
- First ionisation energy
- 13.598 eV
- Oxidation states
- +1, -1
- Discovered
- 1766
Molar mass calculator
Type a formula. Brackets and hydrates work: Ca(OH)2, CuSO4·5H2O.
98.072 g/mol
| Element | Atoms | Ar | Mass | % by mass |
|---|---|---|---|---|
| H Hydrogen | 2 | 1.008 | 2.016 | 2.06% |
| S Sulfur | 1 | 32.06 | 32.060 | 32.69% |
| O Oxygen | 4 | 15.999 | 63.996 | 65.25% |
Moles = mass ÷ molar mass (n = m ÷ M).
Element data from PubChem (US National Library of Medicine). Molar masses use IUPAC standard atomic weights; your exam data sheet may round them (for example Cl = 35.5). Stuck on moles? Try two free chemistry classes.
Reading the periodic table
Each row is a period: elements in period 3 have three shells of electrons. Each column is a group: group 1 metals all have one outer electron and react vigorously with water, while group 18 noble gases have full outer shells and barely react.
The colours show the type of element. Metals are on the left and in the middle, non-metals on the right, and the metalloids (such as silicon and germanium) sit along the staircase between them. The two rows at the bottom are the lanthanides and actinides, pulled out so the table fits on a page.
Using the molar mass calculator
Type a formula exactly as written in chemistry, with capital letters for the start of each symbol:
- ✓ Numbers after a symbol are subscripts: H2SO4 means 2 hydrogen, 1 sulfur and 4 oxygen atoms
- ✓ Brackets multiply everything inside: Ca(OH)2 has 2 oxygen and 2 hydrogen atoms
- ✓ Hydrates use a dot: CuSO4·5H2O (a full stop or * works too)
- ✓ The table shows each element's share of the mass, which is the percentage composition questions ask for
FAQs
How many elements are on the periodic table?＋
118. The last four to be named, in 2016, were nihonium (113), moscovium (115), tennessine (117) and oganesson (118).
How is the periodic table arranged?＋
By atomic number (the number of protons), in rows called periods and columns called groups. Elements in the same group have the same number of outer electrons, so they react in similar ways.
How do you calculate molar mass?＋
Add up the relative atomic masses of every atom in the formula. For water, H2O: 2 x 1.008 + 15.999 = 18.015 g/mol. Type any formula into the calculator to see the working.
How do you convert grams to moles?＋
Divide the mass in grams by the molar mass: moles = mass ÷ molar mass. 10 g of water is 10 ÷ 18.015 = 0.555 mol.
Why does my exam data sheet give different atomic masses?＋
School data sheets usually round relative atomic masses, for example Cl = 35.5 and Cu = 63.5. Use the values your exam board gives in the exam; this tool uses the more precise IUPAC values.
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