Жез (Cu)

chemical element with symbol Cu and atomic number 29

Atomic Number	29
Atomic Weight	63.546
mass number	63

Group	11
Period	4
Block	d

Протон	29 p⁺
Нейтрон	34 n⁰
Электрон	29 e^-

Physical Property

Атомдук Радиус	135 pm 217 pm
molar volume	7,1 cm³/mol
covalent radius	112 pm 115 pm 120 pm 137 pm 132 pm
Metallic Radius	118 pm 128 pm
ionic radius	46 pm 60 pm 77 pm 57 pm 57 pm 65 pm 73 pm 54 pm
Crystal Radius	60 pm 74 pm 91 pm 71 pm 71 pm 79 pm 87 pm 60 pm
Van der Waals radius	200 pm 196 pm 226 pm 349,5 pm
density	8,96 g/cm³ 8 020 kg/m³

Chemical Property

энергия

proton affinity	655,3 kJ/mol
electron affinity	1,235 eV/particle
ionization energy	7,72638 eV/particle 20,29239 eV/particle 36,841 eV/particle 57,38 eV/particle 79,8 eV/particle 103 eV/particle 139 eV/particle 166 eV/particle 198 eV/particle 232,2 eV/particle 265 eV/particle 367,03 eV/particle 400,98 eV/particle 436,04 eV/particle 483,13 eV/particle 518,7 eV/particle 552,8 eV/particle 632,48 eV/particle 670,608 eV/particle 1 690,5 eV/particle 1 800 eV/particle 1 918 eV/particle 2 044 eV/particle 2 179,4 eV/particle 2 307 eV/particle 2 479,1 eV/particle 2 586,954 eV/particle 11 062,4309 eV/particle 11 567,612 eV/particle

enthalpy of vaporization	304,6 kJ/mol
enthalpy of fusion	13,01 kJ/mol
standard enthalpy of formation	337,4 kJ/mol
Электрон

electron shell	2, 8, 18, 1

valence electron	1 ⓘ

electron configuration	[Ar] 3d¹⁰ 4s¹ⓘ 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s¹

oxidation number	-2, 0, 1, 2, 3, 4
electronegativity	10,96 eV/particle 0.1511716 1.9
Electrophilicity Index	1,546403297611602 eV/particle
fundamental state of matter

phase of matter	Solid
gaseous state of matter
Boiling Point	2 833,15 K
Melting Point	1 357,77 K
critical pressure
critical temperature
triple point
appearance
Түс –	Copper #a52a2a #c88033 #c88033
appearance	red-orange metallic luster
refractive index
thermodynamic material property
Thermal Conductivity	401 W/(m K)
thermal expansion	0,0000165 1/K
molar heat capacity	24,44 J/(mol K)
Specific Heat Capacity	0,385 J/(g⋅K)
heat capacity ratio
electrical properties
type	Conductor
electrical conductivity	59 MS/m
electrical resistivity	0,000000017 m Ω
superconductivity
Магнетизм
type	diamagnetic
magnetic susceptibility (Mass)	-0,00000000108 m³/Kg
magnetic susceptibility (Molar)	-0,0000000000686 m³/mol
magnetic susceptibility (Volume)	-0,00000963
magnetic ordering
Curie temperature
Néel temperature
түзүм
Crystal Structure	Face Centered Cubic (FCC)
lattice constant	3,61 Å
Lattice Angles	π/2, π/2, π/2
mechanical property
hardness	874 MPa 3 MPa 369 MPa
bulk modulus	140 GPa
shear modulus	48 GPa
Young's modulus	130 GPa
Poisson's ratio	0,34
speed of sound	3 570 m/s
classification
Category	Transition metals, Transition metals
CAS Group	IB
IUPAC Group	IB
Glawe Number	68
Mendeleev Number	71
Pettifor Number	72
Geochemical Class	first series transition metal
Литофиль элементтери	chalcophile

other

Gas Basicity	632,4 kJ/mol
polarizability	46,5 ± 0,5 a₀
C6 Dispersion Coefficient	253 a₀ 264 a₀
allotrope
Neutron cross section	3,78
Neutron Mass Absorption	0,0021
Кванттык сандар	2S1/2
space group	225 (Fm_3m)

Isotopes of Copper

Stable Isotopes	2
Unstable Isotopes	31
Natural Isotopes	2

⁵²Cu

mass number	52
neutron number	23
relative atomic mass	51,997982 ± 0,000644 Da
g-factor
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life
Спин	3
nuclear quadrupole moment
time of discovery or invention
parity	+

decay mode	intensity
p (proton emission)

⁵³Cu

mass number	53
neutron number	24
relative atomic mass	52,985894 ± 0,000537 Da
g-factor
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life
Спин	3/2
nuclear quadrupole moment
time of discovery or invention
parity	-

decay mode	intensity
p (proton emission)

⁵⁴Cu

mass number	54
neutron number	25
relative atomic mass	53,977198 ± 0,000429 Da
g-factor
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life
Спин	3
nuclear quadrupole moment
time of discovery or invention
parity	+

decay mode	intensity
p (proton emission)

⁵⁵Cu

mass number	55
neutron number	26
relative atomic mass	54,966038 ± 0,000167 Da
g-factor
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	55,9 ± 1,5 ms
Спин	3/2
nuclear quadrupole moment
time of discovery or invention	1987
parity	-

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)

⁵⁶Cu

mass number	56
neutron number	27
relative atomic mass	55,958529278 ± 0,000006864 Da
g-factor
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	80,8 ± 0,6 ms
Спин	4
nuclear quadrupole moment
time of discovery or invention	1987
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)	0.4%

⁵⁷Cu

mass number	57
neutron number	28
relative atomic mass	56,949211686 ± 0,000000537 Da
g-factor	1,7213333333333 ± 0,0046666666666667
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	196,4 ± 0,7 ms
Спин	3/2
nuclear quadrupole moment
time of discovery or invention	1976
parity	-

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

⁵⁸Cu

mass number	58
neutron number	29
relative atomic mass	57,944532283 ± 0,000000604 Da
g-factor	0,571 ± 0,002
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	3,204 ± 0,007 s
Спин	1
nuclear quadrupole moment
time of discovery or invention	1952
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

⁵⁹Cu

mass number	59
neutron number	30
relative atomic mass	58,939496713 ± 0,000000566 Da
g-factor	1,2620666666667 ± 0,0006
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	81,5 ± 0,5 s
Спин	3/2
nuclear quadrupole moment
time of discovery or invention	1947
parity	-

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

⁶⁰Cu

mass number	60
neutron number	31
relative atomic mass	59,937363787 ± 0,000001731 Da
g-factor	0,61 ± 0,00025
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	23,7 ± 0,4 m
Спин	2
nuclear quadrupole moment
time of discovery or invention	1947
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

⁶¹Cu

mass number	61
neutron number	32
relative atomic mass	60,933457375 ± 0,00000102 Da
g-factor	1,4071333333333 ± 0,00033333333333333
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	3,343 ± 0,016 h
Спин	3/2
nuclear quadrupole moment
time of discovery or invention	1937
parity	-

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

⁶²Cu

mass number	62
neutron number	33
relative atomic mass	61,932594803 ± 0,000000683 Da
g-factor	-0,38 ± 0,0004
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	9,672 ± 0,008 m
Спин	1
nuclear quadrupole moment
time of discovery or invention	1936
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

⁶³Cu

mass number	63
neutron number	34
relative atomic mass	62,929597119 ± 0,000000457 Da
g-factor
natural abundance	69,15 ± 0,15
Радиоактивдүүлүк	stable isotope
half-life	Not Radioactive ☢️
Спин	3/2
nuclear quadrupole moment	-0,22 ± 0,015
time of discovery or invention	1923
parity	-

⁶⁴Cu

mass number	64
neutron number	35
relative atomic mass	63,929764001 ± 0,000000458 Da
g-factor	-0,2166 ± 0,0004
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	12,7004 ± 0,0013 h
Спин	1
nuclear quadrupole moment
time of discovery or invention	1936
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	61.52%
β⁻ (β⁻ decay)	38.48%

⁶⁵Cu

mass number	65
neutron number	36
relative atomic mass	64,927789476 ± 0,00000069 Da
g-factor
natural abundance	30,85 ± 0,15
Радиоактивдүүлүк	stable isotope
half-life	Not Radioactive ☢️
Спин	3/2
nuclear quadrupole moment	-0,204 ± 0,014
time of discovery or invention	1923
parity	-

⁶⁶Cu

mass number	66
neutron number	37
relative atomic mass	65,928868804 ± 0,000000696 Da
g-factor	-0,2826 ± 0,0008
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	5,12 ± 0,014 m
Спин	1
nuclear quadrupole moment
time of discovery or invention	1937
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%

⁶⁷Cu

mass number	67
neutron number	38
relative atomic mass	66,92772949 ± 0,000000957 Da
g-factor	1,6780666666667 ± 0,0004
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	61,83 ± 0,12 h
Спин	3/2
nuclear quadrupole moment
time of discovery or invention	1948
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%

⁶⁸Cu

mass number	68
neutron number	39
relative atomic mass	67,929610887 ± 0,0000017 Da
g-factor	2,396 ± 0,0006
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	30,9 ± 0,6 s
Спин	1
nuclear quadrupole moment
time of discovery or invention	1953
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%

⁶⁹Cu

mass number	69
neutron number	40
relative atomic mass	68,929429267 ± 0,0000015 Da
g-factor	1,8943333333333 ± 0,00066666666666667
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	2,85 ± 0,15 m
Спин	3/2
nuclear quadrupole moment
time of discovery or invention	1966
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%

⁷⁰Cu

mass number	70
neutron number	41
relative atomic mass	69,932392078 ± 0,000001161 Da
g-factor	0,22801666666667 ± 0,000083333333333333
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	44,5 ± 0,2 s
Спин	6
nuclear quadrupole moment
time of discovery or invention	1971
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%

⁷¹Cu

mass number	71
neutron number	42
relative atomic mass	70,932676831 ± 0,0000016 Da
g-factor
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	19,4 ± 1,4 s
Спин	3/2
nuclear quadrupole moment
time of discovery or invention	1983
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%

⁷²Cu

mass number	72
neutron number	43
relative atomic mass	71,935820306 ± 0,0000015 Da
g-factor
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	6,63 ± 0,03 s
Спин	2
nuclear quadrupole moment
time of discovery or invention	1983
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%

⁷³Cu

mass number	73
neutron number	44
relative atomic mass	72,936674376 ± 0,000002084 Da
g-factor
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	4,2 ± 0,12 s
Спин	3/2
nuclear quadrupole moment
time of discovery or invention	1983
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	0.029%

⁷⁴Cu

mass number	74
neutron number	45
relative atomic mass	73,93987486 ± 0,0000066 Da
g-factor	-0,5335 ± 0,0006
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	1,606 ± 0,009 s
Спин	2
nuclear quadrupole moment
time of discovery or invention	1987
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	0.075%

⁷⁵Cu

mass number	75
neutron number	46
relative atomic mass	74,941523817 ± 0,00000077 Da
g-factor	0,40276 ± 0,0004
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	1,224 ± 0,003 s
Спин	5/2
nuclear quadrupole moment
time of discovery or invention	1985
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	2.7%

⁷⁶Cu

mass number	76
neutron number	47
relative atomic mass	75,945268974 ± 0,00000098 Da
g-factor	-0,36356666666667 ± 0,0005
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	637,7 ± 5,5 ms
Спин	3
nuclear quadrupole moment
time of discovery or invention	1987
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	7.2%

⁷⁷Cu

mass number	77
neutron number	48
relative atomic mass	76,947543599 ± 0,0000013 Da
g-factor	0,63852 ± 0,00068
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	470,3 ± 1,7 ms
Спин	5/2
nuclear quadrupole moment
time of discovery or invention	1987
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	30.1%

⁷⁸Cu

mass number	78
neutron number	49
relative atomic mass	77,951916524 ± 0,000014312 Da
g-factor	0,039666666666667 ± 0,0005
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	330,7 ± 2 ms
Спин	6
nuclear quadrupole moment
time of discovery or invention	1991
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	50.6%
2n (2-neutron emission)

⁷⁹Cu

mass number	79
neutron number	50
relative atomic mass	78,9544731 ± 0,0001127 Da
g-factor
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	241,3 ± 2,1 ms
Спин	5/2
nuclear quadrupole moment
time of discovery or invention	1991
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	66%
2n (2-neutron emission)

⁸⁰Cu

mass number	80
neutron number	51
relative atomic mass	79,960623 ± 0,000322 Da
g-factor
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	113,3 ± 6,4 ms
Спин
nuclear quadrupole moment
time of discovery or invention	1995
parity

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	58%
2n (2-neutron emission)

⁸¹Cu

mass number	81
neutron number	52
relative atomic mass	80,965743 ± 0,000322 Da
g-factor
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	73,2 ± 6,8 ms
Спин	5/2
nuclear quadrupole moment
time of discovery or invention	2010
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	81%
2n (2-neutron emission)

⁸²Cu

mass number	82
neutron number	53
relative atomic mass	81,972378 ± 0,000429 Da
g-factor
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life	34 ± 7 ms
Спин
nuclear quadrupole moment
time of discovery or invention	2010
parity

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)
2n (2-neutron emission)

⁸³Cu

mass number	83
neutron number	54
relative atomic mass	82,97811 ± 0,000537 Da
g-factor
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life
Спин	5/2
nuclear quadrupole moment
time of discovery or invention	2017
parity	-

decay mode	intensity
β⁻ (β⁻ decay)
β⁻ n (β⁻-delayed neutron emission)
2n (2-neutron emission)

⁸⁴Cu

mass number	84
neutron number	55
relative atomic mass	83,985271 ± 0,000537 Da
g-factor
natural abundance
Радиоактивдүүлүк	☢️ Радиоактивдүү элементтер —
half-life
Спин
nuclear quadrupole moment
time of discovery or invention
parity

decay mode	intensity
β⁻ (β⁻ decay)
β⁻ n (β⁻-delayed neutron emission)

тарых

discoverer or inventor	Known to the ancients.
location of discovery
time of discovery or invention
Этимология	Symbol from Latin: cuprum (island of Cyprus famed for its copper mines).
pronunciation	KOP-er (англисче)

source

Abundance
Abundance in Earth's crust	60 mg/kg
natural abundance (Океан)	0,00025 mg/L
natural abundance (human body)	0,0001 %
natural abundance (meteoroid)	0,011 %
natural abundance (Күн)	0,00007 %
Abundance in Universe	0,000006 %

Nuclear Screening Constants

1	s	0.6614
2	p	3.903
2	s	7.9802
3	d	15.7994
3	p	14.2694
3	s	13.4057
4	s	23.1576

Жез on ChemicalAid

ABC News topic ID	copper
AGROVOC ID	c_1868
Art & Architecture Thesaurus ID	300011020
Australian Educational Vocabulary ID	scot/3512
BNCF Thesaurus ID	2735
Biblioteca Nacional de España ID	XX530125
Bibliothèque nationale de France ID	119470591
Brockhaus Enzyklopädie online ID	kupfer-20
CAS Registry Number	7440-50-8
Canadian Encyclopedia article ID	copper
ChEBI ID	30052
ChEMBL ID	CHEMBL55643
ChemSpider ID	22414
CosIng number	32826
DSSTOX compound identifier	DTXCID503985
DSSTox substance ID	DTXSID2023985
Den Store Danske ID	kobber
DrugBank ID	09130
ECHA Substance Infocard ID	100.028.326
Encyclopedia of China (Third Edition) ID	190458
Encyclopædia Britannica Online ID	science/copper
Encyclopædia Universalis ID	cuivre
EuroVoc ID	316
Europeana Fashion Vocabulary ID	10548
Freebase ID	/m/025rsfk
French Vikidia ID	Cuivre
GND ID	4033734-0
Gran Enciclopèdia Catalana ID	0226407
Great Russian Encyclopedia Online ID	2198522
Grove Art Online ID	T019343
HSDB ID	1622
ICSC ID	0240
IEDB Epitope ID	174839
InChI	InChI=1S/Cu
InChIKey	RYGMFSIKBFXOCR-UHFFFAOYSA-N
Italian Vikidia ID	Rame
KBpedia ID	Copper
KEGG ID	C00070
Klexikon article ID	Kupfer
Krugosvet article	himiya/med
Latvian National Encyclopedia Online ID	154602
Le Monde diplomatique subject ID	sujet/cuivre
Library of Congress authority ID	sh85032278
LiverTox ID	Copper
MeSH descriptor ID	D003300
NALT ID	28946
NDF-RT ID	N0000146034
NDL Authority ID	00561504
NKCR AUT ID	ph123121
Namuwiki ID	구리
National Library of Israel J9U ID	987007562861205171
OmegaWiki Defined Meaning	761
OpenAlex ID	C2991729501
OpenAlex ID	C544778455
Open Food Facts ingredient ID	copper
PACTOLS thesaurus ID	pcrt16pnvNar4g
PM20 ware ID	143156
PSH ID	5785
Probes And Drugs ID	PD013430
PubChem CID	23978
Quora topic ID	Copper-element
RKD thesaurus ID	43430
RxNorm ID	2837
Römpp online ID	RD-11-02420
STW Thesaurus for Economics ID	14299-5
Spanish Cultural Heritage thesauri ID	materias/1181267
Spanish Vikidia ID	Cobre
Store medisinske leksikon ID	kobber
Store norske leksikon ID	kobber
Treccani ID	rame
U.S. National Archives Identifier	10638044
UK Archival Thesaurus ID	f2/mt225/4347/1213
UK Parliament thesaurus ID	9416
UMLS CUI	C0009968
UNESCO Thesaurus ID	concept5524
UNII	789U1901C5
USGS Thesaurus ID	1434
WikiSkripta ID	12119
Wolfram Language entity code	Entity["Mineral", "Copper"]
WordNet 3.1 Synset ID	14659900-n
YSO ID	19074
ZVG number	8240
Zhihu topic ID	19659734

Жез (Cu)

Physical Property

Chemical Property

other

Isotopes of Copper

52Cu

53Cu

54Cu

55Cu

56Cu

57Cu

58Cu

59Cu

60Cu

61Cu

62Cu

63Cu

64Cu

65Cu

66Cu

67Cu

68Cu

69Cu

70Cu

71Cu

72Cu

73Cu

74Cu

75Cu

76Cu

77Cu

78Cu

79Cu

80Cu

81Cu

82Cu

83Cu

84Cu

тарых

source

Nuclear Screening Constants

⁵²Cu

⁵³Cu

⁵⁴Cu

⁵⁵Cu

⁵⁶Cu

⁵⁷Cu

⁵⁸Cu

⁵⁹Cu

⁶⁰Cu

⁶¹Cu

⁶²Cu

⁶³Cu

⁶⁴Cu

⁶⁵Cu

⁶⁶Cu

⁶⁷Cu

⁶⁸Cu

⁶⁹Cu

⁷⁰Cu

⁷¹Cu

⁷²Cu

⁷³Cu

⁷⁴Cu

⁷⁵Cu

⁷⁶Cu

⁷⁷Cu

⁷⁸Cu

⁷⁹Cu

⁸⁰Cu

⁸¹Cu

⁸²Cu

⁸³Cu

⁸⁴Cu