atomic weights
Periodic table numbers
Atomic weights are the relative masses of chemical elements, measured against a standard (carbon-12).
Each element has a characteristic atomic weight based on the weighted average of its naturally occurring isotopes.
The periodic table lists atomic weights alongside element symbols: hydrogen at approximately 1, oxygen at 16, iron at 56.
Scientists use atomic weights to calculate molecular masses and balance chemical equations.
- protonPositive nuclear particle
- isotopesAtomic number twins
- neutronUncharged nuclear particle
- elementBasic substance or factor
- chemical elementsPure atomic substances
mass number · electron · Avogadro's law · stoichiometry · actinides · physics · noble gases · halogens · lanthanides · rare earth elements · periodic table · chemical bonding · chemistry · nuclear chemistry · Mendeleev · valence electrons · weighted average · mass spectrometry
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