Aluminium

This article is about the metallic element. For other uses, see Aluminium (disambiguation).

magnesium ← aluminium → silicon B ↑ Al ↓ Ga 13Al Periodic table
Appearance
Spectral lines of aluminium
General properties
Name, symbol, number	aluminium, Al, 13
Pronunciation	UK i /ˌæljʊˈmɪniəm/ al-ew-min-ee-əm; or US i /əˈluːmɪnəm/ ə-loo-mi-nəm
Element category	other metal
Group, period, block	13, 3, p
Standard atomic weight	26.9815386
Electron configuration	[Ne] 3s2 3p1
Electrons per shell	2, 8, 3 (Image)
Physical properties
Phase	solid
Density (near r.t.)	2.70 g·cm−3
Liquid density at m.p.	2.375 g·cm−3
Melting point	933.47 K, 660.32 °C, 1220.58 °F
Boiling point	2792 K, 2519 °C, 4566 °F
Heat of fusion	10.71 kJ·mol−1
Heat of vaporization	294.0 kJ·mol−1
Specific heat capacity	(25 °C) 24.200 J·mol−1·K−1
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1482 1632 1817 2054 2364 2790
Atomic properties
Oxidation states	3, 2[1], 1[2] (amphoteric oxide)
Electronegativity	1.61 (Pauling scale)
Ionization energies (more)	1st: 577.5 kJ·mol−1
	2nd: 1816.7 kJ·mol−1
	3rd: 2744.8 kJ·mol−1
Atomic radius	143 pm
Covalent radius	121±4 pm
Van der Waals radius	184 pm
Miscellanea
Crystal structure	face-centered cubic
Magnetic ordering	paramagnetic[3]
Electrical resistivity	(20 °C) 28.2 nΩ·m
Thermal conductivity	(300 K) 237 W·m−1·K−1
Thermal expansion	(25 °C) 23.1 µm·m−1·K−1
Speed of sound (thin rod)	(r.t.) (rolled) 5,000 m·s−1
Young's modulus	70 GPa
Shear modulus	26 GPa
Bulk modulus	76 GPa
Poisson ratio	0.35
Mohs hardness	2.75
Vickers hardness	167 MPa
Brinell hardness	245 MPa
CAS registry number	7429-90-5
Most stable isotopes
Main article: Isotopes of aluminium
iso NA half-life DM DE (MeV) DP 26Al trace 7.17×105y β+ 1.17 26Mg ε - 26Mg γ 1.8086 - 27Al 100% 27Al is stable with 14 neutrons
v · d · e · r

Aluminium (UK ⁱ /ˌæljʊˈmɪniəm/ al-ew-min-ee-əm)^[4] or aluminum (US ⁱ /əˈljuːmɪnəm/ ə-lew-mi-nəm) is a silvery white member of the boron group of chemical elements. It has the symbol Al and its atomic number is 13. It is not soluble in water under normal circumstances. Aluminium is the most abundant metal in the Earth's crust, and the third most abundant element, after oxygen and silicon. It makes up about 8% by weight of the Earth's solid surface. Aluminium is too reactive chemically to occur in nature as a free metal.

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Potassium

Appearance
silvery gray Spectral lines of Potassium
General properties
Name, symbol, number	potassium, K, 19
Pronunciation	/pɵˈtæsiəm/ po-TAS-ee-əm
Element category	alkali metal
Group, period, block	1, 4, s
Standard atomic weight	39.0983
Electron configuration	[Ar] 4s1
Electrons per shell	2, 8, 8, 1 (Image)
Physical properties
Phase	solid
Density (near r.t.)	0.862 g·cm−3
Liquid density at m.p.	0.828 g·cm−3
Melting point	336.53 K, 63.38 °C, 146.08 °F
Boiling point
Triple point	336.35 K (63°C), kPa
Heat of fusion	2.33 kJ·mol−1
Heat of vaporization	76.9 kJ·mol−1
Specific heat capacity	(25 °C) 29.6 J·mol−1·K−1
Oxidation states	ide)
Electronegativity	(Pauling scale)
onization energies (more)	1st: 418.8 kJ·mol−1
	2nd: 3052 kJ·mol−1
	3rd: 4420 kJ·mol−1
Atomic radius	227 pm
Covalent radius	203±12 pm
Van der Waals radius	275 pm
Miscellanea
Crystal structure	body-centered cubic
Magnetic ordering	paramagnetic
Electrical resistivity	(20 °C) 72 nΩ·m
Thermal conductivity	(300 K) 102.5 W·m−1·K−1
Thermal expansion	(25 °C) 83.3 µm·m−1·K−1
Speed of sound (thin rod)	(20 °C) 2000 m/s
Young's modulus	3.53 GPa
Shear modulus	1.3 GPa
Bulk modulus	3.1 GPa
Mohs hardness	0.4
Brinell hardness	0.363 MPa
CAS registry number	7440-09-7
Most stable isotopes
Main article: Isotopes of potassium
iso NA half-life DM DE (MeV) DP 39K 93.26% 39K is stable with 20 neutrons 40K 0.012% 1.248(3)×109 y β− 1.311 40Ca ε 1.505 40Ar β+ 1.505 40Ar 41K 6.73% 41K is stable with 22 neutrons

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