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K Potassium
Element Information, Facts, Properties, Trends, Uses, Comparison with other elements

19
K
Potassium
Element 19 of Periodic table is Potassium with atomic number 19, atomic weight 39.0983. Potassium, symbol K, has a Body Centered Cubic structure and Silver color. Potassium is a Alkali Metal element. It is part of group 1 (lithium family). Know everything about Potassium Facts, Physical Properties, Chemical Properties, Electronic configuration, Atomic and Crystal Structure.
19 K - Potassium | SchoolMyKids

Potassium is a chemical element with symbol K (derived from Neo-Latin, kalium) and atomic number 19. It was first isolated from potash, the ashes of plants, from which its name is derived. In the Periodic table, potassium is one of seven elements in column (group) 1 (alkali metals):they all have a single valence electron in their outer electron shell, which they readily give up to create an atom with a positive charge - a cation, and combine with anions to form salts.

It belongs to group 1 of the periodic table having trivial name alkali metals*. Hydrogen resides within this column, but is not considered an alkali metal.

Potassium Facts

Read key information and facts about element Potassium

NamePotassium
Atomic Number19
Atomic SymbolK
Atomic Weight39.0983
PhaseSolid
ColorSilver
Appearancesilvery gray
ClassificationAlkali Metal
Group in Periodic Table1
Group Namelithium family
Period in Periodic Tableperiod 4
Block in Periodic Tables -block
Electronic Configuration[Ar] 4s1
Electronic Shell Structure (Electrons per shell)2, 8, 8, 1
Melting Point336.53 K
Boiling Point1032 K
CAS NumberCAS7440-09-7
Neighborhood Elements
123456789101112131415161718
1
1
H
Hydrogen
1.008

Atomic #

Electronic Shell #

Symbol
Name
Atomic Weight
HGas
HgLiquid
CSolid
Metals
Metalloids
NonMetals
Alkali metals
Alkali earth metals
Lanthanoids
Transition metals
Post-transition metals
Other nonmetals
Halogens
Nobel gas
Actinoids
2
He
Helium
4.003
2
3
Li
Lithium
6.941
4
Be
Beryllium
9.012
5
B
Boron
10.811
6
C
Carbon
12.011
7
N
Nitrogen
14.007
8
O
Oxygen
15.999
9
F
Fluorine
18.998
10
Ne
Neon
20.180
3
11
Na
Sodium
22.990
12
Mg
Magnesium
24.305
13
Al
Aluminium
26.982
14
Si
Silicon
28.085
15
P
Phosphorus
30.974
16
S
Sulfur
32.065
17
Cl
Chlorine
35.453
18
Ar
Argon
39.948
4
19
K
Potassium
39.098
20
Ca
Calcium
40.078
21
Sc
Scandium
44.956
22
Ti
Titanium
47.867
23
V
Vanadium
50.941
24
Cr
Chromium
51.996
25
Mn
Manganese
54.938
26
Fe
Iron
55.845
27
Co
Cobalt
58.933
28
Ni
Nickel
58.693
29
Cu
Copper
63.546
30
Zn
Zinc
65.409
31
Ga
Gallium
69.723
32
Ge
Germanium
72.640
33
As
Arsenic
74.922
34
Se
Selenium
78.960
35
Br
Bromine
79.904
36
Kr
Krypton
83.798
5
37
Rb
Rubidium
85.468
38
Sr
Strontium
87.620
39
Y
Yttrium
88.906
40
Zr
Zirconium
91.224
41
Nb
Niobium
92.906
42
Mo
Molybdenum
95.940
43
Tc
Technetium
98
44
Ru
Ruthenium
101.070
45
Rh
Rhodium
102.906
46
Pd
Palladium
106.420
47
Ag
Silver
107.868
48
Cd
Cadmium
112.411
49
In
Indium
114.818
50
Sn
Tin
118.710
51
Sb
Antimony
121.760
52
Te
Tellurium
127.600
53
I
Iodine
126.904
54
Xe
Xenon
131.293
6
55
Cs
Cesium
132.905
56
Ba
Barium
137.327
57 - 71
La - Lu
Lanthanides
72
Hf
Hafnium
178.490
73
Ta
Tantalum
180.948
74
W
Tungsten
183.840
75
Re
Rhenium
186.207
76
Os
Osmium
190.230
77
Ir
Iridium
192.217
78
Pt
Platinum
195.078
79
Au
Gold
196.967
80
Hg
Mercury
200.590
81
Tl
Thallium
204.383
82
Pb
Lead
207.200
83
Bi
Bismuth
208.980
84
Po
Polonium
209
85
At
Astatine
210
86
Rn
Radon
222
7
87
Fr
Francium
223
88
Ra
Radium
226
89 - 103
Ac - Lr
Actinides
104
Rf
Rutherfordium
261
105
Db
Dubnium
262
106
Sg
Seaborgium
266
107
Bh
Bohrium
264
108
Hs
Hassium
277
109
Mt
Meitnerium
268
110
Ds
Darmstadtium
281
111
Rg
Roentgenium
272
112
Cn
Copernicium
285
113
Nh
Nihonium
284
114
Fl
Flerovium
289
115
Mc
Moscovium
288
116
Lv
Livermorium
292
117
Ts
Tennessine
294
118
Og
Oganesson
294
Lanthanides
57
La
Lanthanum
138.905
58
Ce
Cerium
140.116
59
Pr
Praseodymium
140.908
60
Nd
Neodymium
144.240
61
Pm
Promethium
145
62
Sm
Samarium
150.360
63
Eu
Europium
151.964
64
Gd
Gadolinium
157.250
65
Tb
Terbium
158.925
66
Dy
Dysprosium
162.500
67
Ho
Holmium
164.930
68
Er
Erbium
167.259
69
Tm
Thulium
168.934
70
Yb
Ytterbium
173.040
71
Lu
Lutetium
174.967
Actinides
89
Ac
Actinium
227
90
Th
Thorium
232.038
91
Pa
Protactinium
231.036
92
U
Uranium
238.029
93
Np
Neptunium
237
94
Pu
Plutonium
244
95
Am
Americium
243
96
Cm
Curium
247
97
Bk
Berkelium
247
98
Cf
Californium
251
99
Es
Einsteinium
252
100
Fm
Fermium
257
101
Md
Mendelevium
258
102
No
Nobelium
259
103
Lr
Lawrencium
262

How to Locate Potassium on Periodic Table

Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of electrons. The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and ends at bottom right (atomic number 118). Therefore you can directly look for atomic number 19 to find Potassium on periodic table.

Another way to read periodic table and locate an element is by using group number (column) and period number (row). To locate Potassium on periodic table look for cross section of group 1 and period 4 in the modern periodic table.

Potassium History

The element Potassium was discovered by H. Davy in year 1807 in United Kingdom. Potassium was first isolated by H. Davy in 1807. Potassium derived its name from New Latin potassa, 'potash' (kalium in Latin).

Davy discovered it by using electrolysis on potash.

Potassium Presence: Abundance in Nature and Around Us

The table below shows the abundance of Potassium in Universe, Sun, Meteorites, Earth's Crust, Oceans and Human Body.

 ppb by weight (1ppb =10^-7 %)ppb by atoms (1ppb =10^-7 %)
Abundance in Universe3000100
Abundance in Sun4000100
Abundance in Meteorites710000370000
Abundance in Earth's Crust150000007800000
Abundance in Oceans41600065800
Abundance in Humans2000000320000

Crystal Structure of Potassium

The solid state structure of Potassium is Body Centered Cubic.

The Crystal structure can be described in terms of its unit Cell. The unit Cells repeats itself in three dimensional space to form the structure.

Unit Cell Parameters

The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell edges Lattice Constants (a, b and c)

abc
532.8 pm532.8 pm532.8 pm

and the angles between them Lattice Angles (alpha, beta and gamma).

alphabetagamma
π/2 π/2 π/2

The positions of the atoms inside the unit cell are described by the set of atomic positions ( xi, yi, zi) measured from a reference lattice point.

The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space are described by the 230 space groups (219 distinct types, or 230 if chiral copies are considered distinct.

Space Group NameIm_ 3m 19 K Potassium - Crystal Structure | SchoolMyKids
Oxidation StatesSpace Group Number229
Crystal StructureBody Centered Cubic

Potassium Atomic and Orbital Properties

Potassium atoms have 19 electrons and the electronic shell structure is [2, 8, 8, 1] with Atomic Term Symbol (Quantum Numbers) 2S1/2.

Atomic Number19
Number of Electrons (with no charge)19
Number of Protons19
Mass Number39
Number of Neutrons20
Shell structure (Electrons per energy level)2, 8, 8, 1
Electron Configuration[Ar] 4s1
Valence Electrons4s1
Valence (Valency)1
Main Oxidation States1
Oxidation States-1, 1
Atomic Term Symbol (Quantum Numbers)2S1/2

Bohr Atomic Model of Potassium - Electrons per energy level

19 K Potassium - Electron Shell Structure | SchoolMyKids
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Ground State Electronic Configuration of Potassium - neutral Potassium atom

Abbreviated electronic configuration of Potassium

The ground state abbreviated electronic configuration of Neutral Potassium atom is [Ar] 4s1. The portion of Potassium configuration that is equivalent to the noble gas of the preceding period, is abbreviated as [Ar]. For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. This is important as it is the Valence electrons 4s1, electrons in the outermost shell that determine the chemical properties of the element.

Unabbreviated electronic configuration of neutral Potassium

Complete ground state electronic configuration for the Potassium atom, Unabbreviated electronic configuration

1s2 2s2 2p6 3s2 3p6 4s1

Electrons are filled in atomic orbitals as per the order determined by the Aufbau principle, Pauli Exclusion Principle and Hund’s Rule.

  • As per the Aufbau principle the electrons will occupy the orbitals having lower energies before occupying higher energy orbitals. According to this principle, electrons are filled in the following order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p…
  • The Pauli exclusion principle states that a maximum of two electrons, each having opposite spins, can fit in an orbital.
  • Hund's rule states that every orbital in a given subshell is singly occupied by electrons before a second electron is filled in an orbital.
  • Electron configuration of Potassium
    Atomic Structure of Potassium

    Potassium atomic radius is 243 pm, while it's covalent radius is 196 pm.

    Atomic Radius Calculated

    243 pm (2.43 Å)

    Atomic Radius Empirical

    220 pm (2.2 Å)

    Atomic Volume45.68 cm3/mol
    Covalent Radius196 pm (1.96 Å)
    Van der Waals Radius275 pm
    Neutron Cross Section2.1
    Neutron Mass Absorption 0.0018

    Atomic Spectrum of Potassium

    Atomic Spectrum of Potassium | SchoolMyKids

    Potassium Chemical Properties: Potassium Ionization Energies and electron affinity

    The electron affinity of Potassium is 48.4 kJ/mol.

    Valence1
    Electronegativity0.82
    ElectronAffinity48.4 kJ/mol

    Ionization Energy of Potassium

    Refer to table below for Ionization energies of Potassium

    Ionization energy numberEnthalpy - kJ/mol
    1st418.8
    2nd3052
    3rd4420
    4th5877
    5th7975
    6th9590
    7th11343
    8th14944
    9th16963.7
    10th48610
    11th54490
    12th60730
    13th68950
    14th75900
    15th83080
    16th93400
    17th99710
    18th444880
    19th476063

    Potassium Physical Properties

    Refer to below table for Potassium Physical Properties

    Density0.856 g/cm3(when liquid at m.p density is $0.828 g/cm3)
    Molar Volume45.68 cm3/mol

    Elastic Properties

    Young Modulus-
    Shear Modulus1.3 GPa
    Bulk Modulus 3.1 GPa
    Poisson Ratio-

    Hardness of Potassium - Tests to Measure of Hardness of Element

    Mohs Hardness0.4 MPa
    Vickers Hardness-
    Brinell Hardness0.363 MPa

    Potassium Electrical Properties

    Potassium is Conductor of electricity. Refer to table below for the Electrical properties ofPotassium

    Electrical Conductivity14000000 S/m
    Resistivity7e-8 m Ω
    Superconducting Point-

    Potassium Heat and Conduction Properties

    Thermal Conductivity100 W/(m K)
    Thermal Expansion-

    Potassium Magnetic Properties

    Magnetic TypeParamagnetic
    Curie Point-
    Mass Magnetic Susceptibility6.7e-9 m3/kg
    Molar Magnetic Susceptibility2.62e-10 m3/mol
    Volume Magnetic Susceptibility0.00000574

    Optical Properties of Potassium

    Refractive Index-

    Acoustic Properties of Potassium

    Speed of Sound2000 m/s

    Potassium Thermal Properties - Enthalpies and thermodynamics

    Refer to table below for Thermal properties of Potassium

    Melting Point336.53 K (63.38°C, 146.084 °F)
    Boiling Point1032 K (758.85°C, 1397.93 °F)
    Critical Temperature2223 K
    Superconducting Point-

    Enthalpies of Potassium

    Heat of Fusion2.33 kJ/mol
    Heat of Vaporization76.9 kJ/mol
    Heat of Combustion-182 J/(kg K)

    Potassium Isotopes - Nuclear Properties of Potassium

    Potassium has 24 isotopes, with between 32 and 55 nucleons. Potassium has 2 stable naturally occuring isotopes.

    Isotopes of Potassium - Naturally occurring stable Isotopes: 39K, 41K.

    IsotopeZNIsotope Mass% AbundanceT halfDecay Mode
    32K191332Synthetic
    33K191433Synthetic
    34K191534Synthetic
    35K191635Synthetic
    36K191736Synthetic
    37K191837Synthetic
    38K191938Synthetic
    39K19203993.2581%Stable
    40K1921400.0117%StableN/A
    41K1922416.7302%StableN/A
    42K192342Synthetic
    43K192443Synthetic
    44K192544Synthetic
    45K192645Synthetic
    46K192746Synthetic
    47K192847Synthetic
    48K192948Synthetic
    49K193049Synthetic
    50K193150Synthetic
    51K193251Synthetic
    52K193352Synthetic
    53K193453Synthetic
    54K193554Synthetic
    55K193655Synthetic