🌿 THE EARTH 🌍

Earth atmospheric layers

List of timelines

• Solar irradiance
• Radiative flux
• Effect of Sun angle on climate
• Atmospheric refraction
  
• 
  
• atmospheric particulate matter,
  

• effects of climate change
  

• Earth rotation, ΔT
• Geocentric orbit.
  
• ECEF
• ECI (coordinates)
• geocentric coordinates.
  
• Local tangent plane coordinates
• Sphericity of the Earth
  
• Equatorial bulge
• geocentric coordinate systems
  
• Geodetic coordinates
  
• Planetary coordinate system
• Reference frame

• Parallax in astronomy.
  
• 
  

• Planetary phase
• 
  
• geologic map
  
• 
  
• surface weather analyses
  
• Cyclogenesis
• Explosive cyclogenesis
• Cyclolysis
• 
  
• sequence stratigraphy
  
• Cratonic sequence – Very large-scale lithostratographic sequence
• Cyclostratigraphy – Study of astronomically forced climate cycles within sedimentary successions
• Biostratigraphy
• Chronostratigraphy

https://scied.ucar.edu/learning-zone/atmosphere/layers-earths-atmosphere

core study

Seismology

https://ocw.mit.edu/courses/12-510-introduction-to-seismology-spring-2010/pages/lecture-notes/

https://archive.nptel.ac.in/courses/105/108/105108076/

Metallic radius

As you can see, metallic radius is defined as one-half of the distance between the nuclei of two atoms in crystal or between two adjacent metal ions in the metallic lattice.

Metallic radii:
- decrease across the period due to increase in the effective nuclear charge.
- increase down the group due to increase in principal quantum number.

Points to Remember:

1. The distance of each atom will be same because group of atoms are from the same metal.
2. Metallic Radii decrease across the period because of increase in the effective nuclear charge.
3. Metallic Radius increases down the group because new shell is added.
4. Metallic radii are always biggest for the highest coordination number.

Group-wise Metallic Radii

Group 1: Alkali Metals

• Atomic Number 3: Li - 152 pm
• Atomic Number 11: Na - 186 pm
• Atomic Number 19: K - 227 pm
• Atomic Number 37: Rb - 248 pm
• Atomic Number 55: Cs - 262 pm
• Atomic Number 87: Fr - 270 pm (estimated)

Group 2: Alkaline Earth Metals

• Atomic Number 4: Be - 112 pm
• Atomic Number 12: Mg - 160 pm
• Atomic Number 20: Ca - 197 pm
• Atomic Number 38: Sr - 215 pm
• Atomic Number 56: Ba - 222 pm
• Atomic Number 88: Ra - 247 pm (estimated)

Group 3-12: Transition Metals

• Atomic Number 22: Ti - 147 pm
• Atomic Number 24: Cr - 140 pm
• Atomic Number 26: Fe - 126 pm
• Atomic Number 27: Co - 125 pm
• Atomic Number 28: Ni - 124 pm
• Atomic Number 29: Cu - 128 pm
• Atomic Number 30: Zn - 139 pm
• Atomic Number 40: Zr - 160 pm
• Atomic Number 42: Mo - 139 pm
• Atomic Number 74: W - 139 pm
• Atomic Number 78: Pt - 139 pm

Group 13: Boron Group

• Atomic Number 5: B (not metallic)
• Atomic Number 13: Al - 143 pm
• Atomic Number 31: Ga - 135 pm
• Atomic Number 49: In - 156 pm
• Atomic Number 81: Tl - 156 pm

Group 14: Carbon Group

• Atomic Number 6: C (not metallic in its common form)
• Atomic Number 14: Si (not metallic in its common form)
• Atomic Number 32: Ge - 122 pm (metalloid)
• Atomic Number 50: Sn - 140 pm
• Atomic Number 82: Pb - 175 pm

Group 15: Nitrogen Group

• Atomic Number 7: N (not metallic)
• Atomic Number 15: P (not metallic)
• Atomic Number 33: As - 120 pm (metalloid)
• Atomic Number 51: Sb - 140 pm
• Atomic Number 83: Bi - 156 pm

Group 16: Chalcogens

• Atomic Number 8: O (not metallic)
• Atomic Number 16: S (not metallic)
• Atomic Number 34: Se (not metallic)
• Atomic Number 52: Te - 140 pm (metalloid)
• Atomic Number 86: Po - 150 pm (metalloid)

Group 17: Halogens

• Atomic Number 9: F (not metallic)
• Atomic Number 17: Cl (not metallic)
• Atomic Number 35: Br (not metallic)
• Atomic Number 53: I (not metallic)
• Atomic Number 85: At (not metallic)

Summary

• Alkali and Alkaline Earth Metals have larger metallic radii due to their larger atomic sizes and single/double valence electrons.
• Transition Metals exhibit varying metallic radii due to their unique electron configurations and bonding characteristics.
• Metalloids (like Ge, As, and Sb) have intermediate metallic properties.
• Nonmetals (like N, O, F) and many elements in Groups 14 to 17 do not have metallic radii as they do not participate in metallic bonding.

Atomic Number	Element	Metallic Radius (pm)

1

Hydrogen

37

2

Helium

-

3

Lithium

152

4

Beryllium

112

5

Boron

87

6

Carbon

70

7

Nitrogen

65

8

Oxygen

60

9

Fluorine

57

10

Neon

-

11

Sodium

186

12

Magnesium

160

13

Aluminum

143

14

Silicon

118

15

Phosphorus

110

16

Sulfur

104

17

Chlorine

99

18

Argon

-

19

Potassium

227

20

Calcium

197

21

Scandium

162

22

Titanium

147

23

Vanadium

141

24

Chromium

139

25

Manganese

139

26

Iron

126

27

Cobalt

125

28

Nickel

124

29

Copper

128

30

Zinc

139

31

Gallium

135

32

Germanium

122

33

Arsenic

118

34

Selenium

116

35

Bromine

114

36

Krypton

-

37

Rubidium

248

38

Strontium

215

39

Yttrium

180

40

Zirconium

159

41

Niobium

146

42

Molybdenum

139

43

Technetium

134

44

Ruthenium

132

45

Rhodium

134

46

Palladium

139

47

Silver

144

48

Cadmium

148

49

Indium

145

50

Tin

139

51

Antimony

139

52

Tellurium

139

53

Iodine

133

54

Xenon

-

55

Cesium

262

56

Barium

211

57

Lanthanum

208

58

Cerium

198

59

Praseodymium

196

60

Neodymium

185

61

Promethium

174

62

Samarium

175

63

Europium

188

64

Gadolinium

181

65

Terbium

182

66

Dysprosium

180

67

Holmium

175

68

Erbium

175

69

Thulium

173

70

Ytterbium

172

71

Lutetium

171

72

Hafnium

159

73

Tantalum

146

74

Tungsten

139

75

Rhenium

139

76

Osmium

136

77

Iridium

136

78

Platinum

139

79

Gold

144

80

Mercury

152

81

Thallium

156

82

Lead

175

83

Bismuth

156

84

Polonium

150

85

Astatine

202

86

Radon

-

87

Francium

270

88

Radium

215

89

Actinium

200

90

Thorium

175

91

Protactinium

165

92

Uranium

156

93

Neptunium

156

94

Plutonium

157

95

Americium

158

96

Curium

157

97

Berkelium

160

98

Californium

163

99

Einsteinium

166

100

Fermium

167

101

Mendelevium

170

102

Nobelium

171

103

Lawrencium

172

104

Rutherfordium

175

105

Dubnium

175

106

Seaborgium

176

107

Bohrium

177

108

Hassium

178

109

Meitnerium

179

110

Darmstadtium

180

111

Roentgenium

181

112

Copernicium

182

113

Nihonium

184

114

Flerovium

185

115

Moscovium

186

116

Livermorium

187

117

Tennessine

188

118

Oganesson

189

Van der Waals radius

The van der Waals radius is the distance, where the attractive and repulsive forces between the two nonbonded atoms are equal.

The Van der Waals radius is equal to one half the distance between two unbonded atoms when the electrostatic forces between them are balanced. In other words, it is half of the closest distance between two atoms that aren't bonded or within the same molecule. Picometers (pm) are typically the unit used to report the value.

The distance reflects the action of intermolecular forces (e.g., dipole-dipole and dispersion forces) and is related to van der Waals interactions. Knowing the van der Waals radius is helpful when predicting how closely atoms will pack to form a solid.

Van der Waals radius is measured in the nonbonding state. It can't be measured in the liquid and solid-state as the atoms are bonded to each other in such state.

Therefore Van der Waals radius is measured only in the gaseous state.

Definition 2

What is Van Der Waals Radius 

The Van der Waals radius is a measure of the effective size of an atom or molecule. It is defined as half the distance between the nuclei of two adjacent, non-bonded atoms of the same element in a solid or molecular crystal when they are at their closest approach without any significant repulsive forces between them. In simpler terms, it represents the distance at which two atoms, if they were not bonded, would come closest to each other due to the attractive and repulsive forces between their electron clouds.

For example, imagine two helium (He) atoms that are not chemically bonded but are brought close together in a solid. At a certain distance, the attractive forces between their electron clouds dominate, causing them to approach each other. However, if they get too close, the repulsive forces between the electron clouds and the positively charged nuclei start to push them apart. The Van der Waals radius for helium represents the equilibrium distance at which these attractive and repulsive forces are balanced.

Role of Van Der Waals Radius 

The Van der Waals radius holds significant importance in the realms of chemistry and physics, playing a pivotal role in various key areas. Firstly, it is central to understanding intermolecular forces, where the balance between attractive London dispersion forces and repulsive forces, regulated by the Van der Waals radius, dictates whether atoms or molecules form bonds or engage in weak interactions. In the solid state, the Van der Waals radius becomes crucial for molecular packing in a crystal lattice, determining packing efficiency and crystal structure across various materials. Additionally, the Van der Waals equation of state, incorporating the Van der Waals radius, is instrumental in analyzing the behavior of real gases. This equation provides corrections for the finite size of gas molecules, particularly at high pressures and low temperatures, explaining deviations from ideal gas behavior.

Covalent radius Vs Van der Waals radius

Covalent radius is half of the internuclear separation between the nuclei of two single-bonded atoms of the same species (homonuclear). 

While van der Waals radius is used to define half of the distance between the closest approach of two non-bonded atoms of a given element.

Van der Waals radii can be used to study nonbonded (especially intermolecular) interactions.

https://pediaa.com/what-is-the-difference-between-van-der-waals-radius-and-covalent-radius/#Van%20Der%20Waals%20Radius

Here’s a list of the van der Waals radii of the periodic table elements by atomic number: Atomic Number Element Van der Waals Radius (pm) 1 Hydrogen 120 2 Helium 140 3 Lithium 182 4 Beryllium 153 5 Boron 192 6 Carbon 170 7 Nitrogen 155 8 Oxygen 152 9 Fluorine 147 10 Neon 154 11 Sodium 227 12 Magnesium 173 13 Aluminum 184 14 Silicon 210 15 Phosphorus 180 16 Sulfur 180 17 Chlorine 175 18 Argon 188 19 Potassium 275 20 Calcium 231 21 Scandium 212 22 Titanium 206 23 Vanadium 200 24 Chromium 192 25 Manganese 192 26 Iron 190 27 Cobalt 188 28 Nickel 169 29 Copper 140 30 Zinc 139 31 Gallium 185 32 Germanium 210 33 Arsenic 185 34 Selenium 185 35 Bromine 188 36 Krypton 202 37 Rubidium 303 38 Strontium 262 39 Yttrium 248 40 Zirconium 206 41 Niobium 198 42 Molybdenum 193 43 Technetium 188 44 Ruthenium 187 45 Rhodium 185 46 Palladium 180 47 Silver 160 48 Cadmium 158 49 Indium 193 50 Tin 217 51 Antimony 207 52 Tellurium 207 53 Iodine 198 54 Xenon 216 55 Cesium 303 56 Barium 266 57 Lanthanum 271 58 Cerium 251 59 Praseodymium 249 60 Neodymium 244 61 Promethium 245 62 Samarium 244 63 Europium 245 64 Gadolinium 244 65 Terbium 243 66 Dysprosium 240 67 Holmium 240 68 Erbium 239 69 Thulium 238 70 Ytterbium 237 71 Lutetium 263 72 Hafnium 207 73 Tantalum 204 74 Tungsten 198 75 Rhenium 193 76 Osmium 190 77 Iridium 189 78 Platinum 175 79 Gold 166 80 Mercury 202 81 Thallium 207 82 Lead 202 83 Bismuth 207 84 Polonium 202 85 Astatine 202 86 Radon 220 87 Francium 270 88 Radium 215 89 Actinium 200 90 Thorium 175 91 Protactinium 175 92 Uranium 186 93 Neptunium 186 94 Plutonium 187 95 Americium 188 96 Curium 189 97 Berkelium 190 98 Californium 191 99 Einsteinium 192 100 Fermium 193 101 Mendelevium 194 102 Nobelium 195 103 Lawrencium 196 104 Rutherfordium 197 105 Dubnium 198 106 Seaborgium 199 107 Bohrium 200 108 Hassium 201 109 Meitnerium 202 110 Darmstadtium 203 111 Roentgenium 204 112 Copernicium 205 113 Nihonium 206 114 Flerovium 207 115 Moscovium 208 116 Livermorium 209 117 Tennessine 210 118 Oganesson 211 Note: The values are approximate and can vary based on different sources. Some noble gases do not have defined van der Waals radii as they do not typically form van der Waals interactions.