hydrogen

10,000,000

sulfur

95

helium

1,400,000

iron

80

oxygen

6,800

argon

42

carbon

3,000

aluminum

19

neon

2,800

sodium

17

nitrogen

910

calcium

17

magnesium

290

all other elements

50

silicon

250

.

.

Element

Atomic no.

% by weight

oxygen

8

46.6

silicon

14

27.72

aluminum

13

8.13

iron

26

5

calcium

20

3.63

sodium

11

2.83

potassium

19

2.59

magnesium

12

2.09

titanium

22

0.44

hydrogen

1

0.14

phosphorus

15

0.12

manganese

25

0.1

名稱

分子式

莫耳分率

氮

N₂

0.781

氧

O₂

0.209

氬

Ar

0.009

二氧化碳

CO₂

0.0004

Element

Atomic no.

Percentage

Role

oxygen

8

65.0

cellular respiration, component of water

carbon

6

18.5

basis of organic molecules

hydrogen

1

9.5

component of water and most organic molecules, electron carrier

nitrogen

7

3.3

component of all proteins and nucleic acids

calcium

20

1.5

component of bones and teeth, triggers muscle contraction

phosphorus

15

1.0

component of nucleic acids, important in energy transfer

potassium

19

0.4

min positive ion inside cells, important in nerve function

sulfur

16

0.3

component of most proteins

sodium

11

0.2

main positive ion outside cells, important in nerve function

chlorine

17

0.2

main negative ion outside cells

magnesium

12

0.1

essential component of many energy-transferring enzymes

iron

26

trace

essential component of hemoglobin in the blood

copper

29

trace

component of many enzymes

molybdenum

42

trace

component of many enzymes

zinc

30

trace

component of some enzymes

iodine

53

trace

component of thyroid hormone