1) Aluminum is the thirteenth element on the periodic table and is denoted by the atomic symbol Al. It has an atomic number of 13 and an atomic mass of 26.9815384 unified atomic mass units.
Aluminum is a solid at standard temperature and pressure (STP), with a melting point of 660.32 °C and a boiling point of 2519 °C. It has a mass density of 2.7 g/cm^3 and a sound speed of 5100 m/s. Its thermal conductivity is 235 W/(m K).
In terms of electromagnetic properties, aluminum is a conductor and paramagnetic, with a resistivity of 2.6x10^-8 Ω m. It is silver in color.
Aluminum is a reactive element with a valence of 3, an electronegativity of 1.61, an electron affinity of 0.44 eV, and a first ionization energy of 5.985 eV.
The atomic radius of aluminum in its electronic ground state is 125 picometers.
Aluminum is the 14th most abundant element in the universe, the 3rd most abundant in the Earth's crust, and the 21st most abundant in the human body.
Aluminum has one stable isotope: Al-27 (100%). It also has unstable isotopes, including Al-26, which has a half-life of 0.717 million years.
The CAS number for aluminum is 7429-90-5 and its PubChem CID number is CID5359268.
source: [Wolfram|Alpha page for aluminum](https://www.wolframalpha.com/input?i=aluminum).