2019-09-02 Bloomberg Businessweek

11

PERIODIC TABLE OF CONTENTS

shown to be true. Increasing

scientific acceptance of these

theories accelerated research

into the material world and

itsindustrialandcommercial

applications.Mendeleevhimself

tookpartin this,investigating

processes related to Russian

coal, oil, and even cheese pro-

duction during the country’s

fitful drive to modernize.

Since his death from influ-

enza in 1907, the table has

changed some, but its fun-

damental organization

remains. Each element has a

one- or two-letter chemical

symbol, usually derived from its

commonnamebutsometimes

fromanotherlanguage,mak-

inggold,forexample,“Au”

fortheLatinaurum. The

atomicnumbertalliesthepro-

tonsin theatom’snucleus.

Thestandardatomicmassis

sometimesgiventomultiple

decimalplaces,withthenum-

berin parenthesesif it’sfor

thelongest-livedisotope.

Thecolumnsdepict

elements that have similar

chemical properties. The alkali

metals, shown in the first col-

umn on the left, for example,

have one electron in their outer

shell and therefore tend to

bond particularly well with the

halogens, in the second col-

umn from the right, which have

seven electrons in their outer

shell and lack the single elec-

tron needed to complete it.

That’s how we get compounds

such as sodium chloride—table

salt—and potassium iodide,

which helps protect the thyroid

from the effects of radiation.

The column on the far right

shows the noble gases, whose

outer electron shells are full,

making most of these ele-

ments useful in lighting since

they won’t react with others.

In most periodic tables, the

lanthanides and actinides are

placed in rows at the bottom to

avoid making the table imprac-

tically wide.

Mendeleev didn’t get every-

thing right: He believed that

elements were unique and

resisted the idea that they

had the same building blocks.

He also produced a convo-

luted case that ether was an

element. But he got the basic

design right, and that’s why

he’s regarded as its inventor

today—and why its sesquicen-

tennial is being celebrated as

the International Year of the

Periodic Table.

2

He

Helium

10

Ne

Neon

5

B

Boron

6

C

Carbon

7

N

Nitrogen

8

O

Oxygen

9

F

Fluorine

16

S

Sulfur

17

Cl

Chlorine

15

P

Phosphorus

34

Se

Selenium

35

Br

Bromine

53

I

Iodine

18

Ar

Argon

13

Al

Aluminum

14

Si

Silicon

33

As

Arsenic

52

Te

Tellurium

85

At

Astatine

70

Yb

Ytterbium

36

Kr

Krypton

31

Ga

Gallium

32

Ge

Germanium

51

Sb

Antimony

29

Cu

Copper

30

Zn

Zinc

79

Au

Gold

64

Gd

Gadolinium

111

Rg

Roentgenium

96

Cm

Curium

113

Nh

Nihonium

98

Cf

Californium

114

Fl

Flerovium

99

Es

Einsteinium

115

Mc

Moscovium

100

Fm

Fermium

116

Lv

Livermorium

101

Md

Mendelevium

117

Ts

Tennessine

102

No

Nobelium

80

Hg

Mercury

65

Tb

Terbium

54

Xe

Xenon

49

In

Indium

50

Sn

Tin

47

Ag

Silver

48

Cd

Cadmium

112

Cn

Copernicium

97

Bk

Berkelium

86

Rn

Radon

71

Lu

Lutetium

81

Tl

Thallium

66

Dy

Dysprosium

82

Pb

Lead

67

Ho

Holmium

83

Bi

Bismuth

68

Er

Erbium

84

Po

Polonium

69

Tm

Thulium

118

Og

Oganesson

103

Lr

Lawrencium

A neon sign in a design

lab at Hong Kong

Polytechnic

Minerals glowing under

UV light near Narsaq,

Greenland

Warning signs at the

Berkeley cyclotron

Making salt at Netarts

Bay on the Oregon

coast

A display at a facility

that extracts gold from

discarded motherboards

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