Rubidium Element (Periodic Table)

Rubidium

Rubidium (Rb) is a chemical element of the periodic table, located in group 1 and period 5, and has the atomic number 37. It is a very soft, silvery-white alkali metal whose name comes from the Latin word “rubidus” (which means the deepest red). It is a highly reactive metal.

group
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
period
1
1
H
2
He
2
3
Li
4
Be
5
B
6
C
7
N
8
O
9
F
10
Ne
3
11
Na
12
Mg
13
Al
14
Si
15
P
16
S
17
Cl
18
Ar
4
19
K
20
Ca
21
Sc
22
Ti
23
V
24
Cr
25
Mn
26
Fe
27
Co
28
Ni
29
Cu
30
Zn
31
Ga
32
Ge
33
As
34
Se
35
Br
36
Kr
5
37
Rb
38
Sr
39
Y
40
Zr
41
Nb
42
Mo
43
Tc
44
Ru
45
Rh
46
Pd
47
Ag
48
Cd
49
In
50
Sn
51
Sb
52
Te
53
I
54
Xe
6
55
Cs
56
Ba
72
Hf
73
Ta
74
W
75
Re
76
Os
77
Ir
78
Pt
79
Au
80
Hg
81
Tl
82
Pb
83
Bi
84
Po
85
At
86
Rn
7
87
Fr
88
Ra
104
Rf
105
Db
106
Sg
107
Bh
108
Hs
109
Mt
110
Ds
111
Rg
112
Cn
113
Nh
114
Fl
115
Mc
116
Lv
117
Ts
118
Og
57
La
58
Ce
59
Pr
60
Nd
61
Pm
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
68
Er
69
Tm
70
Yb
71
Lu
89
Ac
90
Th
91
Pa
92
U
93
Np
94
Pu
95
Am
96
Cm
97
Bk
98
Cf
99
Es
100
Fm
101
Md
102
No
103
Lr
– s block

Rubidium Applications (or Uses)

Here are the applications (or uses) of rubidium:

  • Rubidium is used to give a purple color to fireworks
  • Rubidium is used as a getter in vacuum tubes
  • Rubidium is used as a propellant in ion engines used by space vehicles
  • Rubidium is used in the manufacture of photocells
  • Rubidium is used as an ingredient in the manufacture of glass
  • Rubidium is used in a positron emission tomography (PET) scan
  • Rubidium is used to determine the age of rocks by the rubidium-strontium dating method

Rubidium Facts

Here are the facts about rubidium:

  • Rubidium has a density higher than water, and so it does not float on water
  • Rubidium was discovered using a flame emission spectroscopy method
  • Rubidium is the second most electropositive element among stable alkali metals
  • Rubidium is the twenty-second most abundant element on earth
  • Rubidium melts just above the body temperature, at 39.30 °C
  • Rubidium ignites in the air and reacts violently with water, so it is kept in mineral oil

FAQs on Rubidium Element

Rubidium
‣ What does rubidium look like?

Appearance: grey white
‣ Who discovered rubidium?

Discovery: Robert Bunsen and Gustav Kirchhoff (1861)
First isolation: George de Hevesy
‣ Where is rubidium found on the periodic table?

Rubidium Periodic Table

Location: Rubidium is found in the first column of the periodic table below the potassium element.
‣ What is the atomic number of rubidium?

Atomic number (Z): 37
‣ What is the symbol for rubidium?

Symbol: Rb
‣ What is the atomic weight of rubidium?

Standard atomic weight: 85.4678
‣ Which block does rubidium belong to?

Block: s-block
‣ Rubidium is located in what group on the periodic table?

Group: 1 (hydrogen and alkali metals)
‣ What period is rubidium in?

Period: 5
‣ What is the atomic radius of rubidium?

Atomic radius: empirical: 248 pm
Rubidium covalent radius: 220±9 pm
Rubidium Van der Waals radius: 303 pm
‣ What is rubidium’s melting point?

Melting point: 312.45 K (39.30 °C, 102.74 °F)
‣ What is the boiling point of rubidium?

Boiling point: 961 K (688 °C, 1270 °F)
Rubidium critical point: 2093 K, 16 MPa (extrapolated)
‣ How many electron shells does rubidium have?

Electrons per shell: 2, 8, 18, 8, 1
‣ What is rubidium electron configuration?

Electron configuration: [Kr] 5s1
‣ What is rubidium ionization energy?

Ionization energies:
1st: 403 kJ/mol
2nd: 2632.1 kJ/mol
3rd: 3859.4 kJ/mol
‣ What is the phase of rubidium?

Phase (at r.t): solid
‣ What is rubidium’s density?

Density (near r.t): 1.532 g/cm3
when liquid (at m.p): 1.46 g/cm3
Rubidium magnetic ordering: paramagnetic
Rubidium natural occurrence: primordial
Oxidation state of rubidium: +1
‣ What’s the electronegativity of rubidium?

Electronegativity: Pauling scale: 0.82
Rubidium heat of fusion: 2.19 kJ/mol
Rubidium heat of vaporization: 69 kJ/mol
Rubidium molar heat capacity: 31.060 J/(mol K)
Rubidium molar magnetic susceptibility: +17.0 × 10-6 cm3/mol (303 K)
Speed of sound in rubidium: 1300 m/s (at 20 °C)
Crystal structure of rubidium: body-centered cubic (bcc)
Rubidium thermal expansion: 90 µm/(m.K) (at r.t)
Thermal conductivity of rubidium: 58.2 W/(m.K)
Rubidium electrical resistivity: 128 nΩ.m (at 20 °C)
‣ What’s the hardness of rubidium?

Mohs hardness: 0.3
Brinell hardness: 0.216 MPa
Young’s modulus of rubidium: 2.4 Gpa
Bulk modulus of rubidium: 2.5 GPa
Rubidium CAS number: 7440-17-7

‣ Rubidium vapor pressure

Vapor pressure
P (Pa)1101001 k10 k100 k
at T (K)434486552641769958

‣ How many isotopes does rubidium have?

Main isotopes of rubidium
IsotopeAbundanceHalf-life (t1/2)Decay modeProduct
83Rbsyn86.2 dε
γ
83Kr
84Rbsyn32.9 dε
β+
γ
β
83Kr
84Kr

84Sr
85Rb72.17 %stable
86Rbsyn18.7 dβ
γ
86Sr
87Rb27.83 %4.9 × 1010 yβ87Sr

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