Main physical, chemical and biochemical properties of precious metals (1)

(A) the basic physical properties of the basic physical properties of the noble metal elements listed in Table 1.
As seen from the data listed in Table 1, the density, melting point and boiling point of the noble metal decrease with the order of Ru, Rh, Pd, Ag series and Os, Ir, Pt, Au series, and the machinability is improved. Among them, helium is the heaviest metal on the earth, which is 22.65 times the weight of water.

Table 1   Basic physical properties of precious metals

Physical properties

ruthenium

rhodium

palladium

silver

osmium

iridium

platinum

gold

Atomic number

44

45

46

47

76

77

78

79

Atomic mass

101.07

102.9

106.4

107.9

190.2

192.2

195

196.7

Crystal structure

Close hexagonal

Face-centered cube

Face-centered cube

Face-centered cube

Close hexagonal

Face-centered cube

Face-centered cube

Face-centered cube

Atomic radius /10 -10 m

1.25

1.25

1.28

1.34

1.26

1.27

1.3

1.34

Atomic volume //10 -30 m

8.3

8.5

8.9

10.21

8.5

8.6

9.12

10.1

Hardness ( diamond = 10 )

6.5

　

5

2.5

7

6.5

4.5

2.5

Density / ( g / cm 3 )

12.45

12.41

12.02

10.49

22.61

22.65

21.45

19.32

Melting point / °C

2427

1966

1550

961

3027

2454

1770

1063

Boiling point / °C

4119

3727

2900

2164

About 5020

4500

3824

2808

Specific heat capacity / ( J / g )

0.231

0.247

0.245

0.234

0.129

0.129

0.131

0.129

Resistivity / [μΩ / ( cm · °C)

6.8

4.33

9.93

1.59

8.12

4.71

9.85

2.06

Temperature coefficient of resistance / (1/ ° C)

0.0042

0.00463

0.0038

0.0041

0.0042

0.00427

0.00393

0.004

The gold is golden yellow, the enamel is blue-gray, and the rest are silver-white. The processed dense metal surface has a strong ability to reflect light.
Gold and silver have the best processing properties. 1g gold can be drawn into filaments of 3km length. Platinum and processing properties are best in platinum group metals. Pure platinum can be cold rolled to 0.0025mm thick and 0.000127mm forged. The platinum foil is drawn into a filament with a diameter of only 0.001 mm; the platinum group metal has a strong adsorption gas characteristic, and the sponge-like platinum can absorb more than 114 times its volume of hydrogen, and can reach its own volume of 3,000. Times, é“‘ also has a similar nature. The conductivity of platinum and platinum-rhodium alloy wire, stable temperature coefficient of resistance and high melting point are important materials for accurate measurement of high temperature temperature and the benchmark for temperature correction.
Usually, precious metals and their alloys are machined into wires, sheets, tubes, plates and shaped materials of various specifications and processed into various components. It can also be used by plating, coating, coating, and the like.

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