Sisyo

Caesium,₅₅Cs

Caesium
Pronunciation	/ˈsiːziəm/​(SEE-zee-əm)
Alternative name	cesium (US)
Appearance	pale gold
Standard atomic weightAr°(Cs)
	132.90545196±0.00000006 132.91±0.01(pinaikli)
Caesium in theperiodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Rb ↑ Cs ↓ Fr xenon←caesium→barium
Atomic number(Z)	55
Group	1
Period	6
Block	s-block
Electron configuration	[Xe] 6s1
Electrons per shell	2, 8, 18, 18, 8, 1
Physical properties
PhaseatSTP	solido
Melting point	301.7K​(28.5 °C, ​83.3 °F)
Boiling point	944 K ​(671 °C, ​1240 °F)
Density(at 20° C)	1.886 g/cm3
when liquid (atm.p.)	1.843 g/cm3
Critical point	1938 K, 9.4 MPa
Heat of fusion	2.09kJ/mol
Heat of vaporization	63.9 kJ/mol
Molar heat capacity	32.210 J/(mol·K)
Vapor pressure P(Pa) 1 10 100 1 k 10 k 100 k atT(K) 418 469 534 623 750 940
Atomic properties
Oxidation states	−1,+1(isang matapang na panimulang oksido)
Electronegativity	Pauling scale: 0.79
Ionization energies	1st: 375.7 kJ/mol 2nd: 2234.3 kJ/mol 3rd: 3400 kJ/mol
Atomic radius	empirical: 265pm
Covalent radius	244±11 pm
Van der Waals radius	343 pm
Mga linyang espektral ng caesium
Other properties
Crystal structure	​body-centered cubic(bcc) (cI2)
Lattice constant	a= 616.2 pm (at 20 °C)
Thermal expansion	92.6×10−6/K (at 20 °C)
Thermal conductivity	35.9 W/(m⋅K)
Electrical resistivity	205 nΩ⋅m (at 20 °C)
Magnetic ordering	paramagnetic
Young's modulus	1.7 GPa
Bulk modulus	1.6 GPa
Mohs hardness	0.2
Brinell hardness	0.14 MPa
CAS Number	7440-46-2
History
Naming	mula Latincaesius,na ang kahulugan ay "bluish grey", for its spectral colours
Discovery	Robert BunsenandGustav Kirchhoff(1860)
First isolation	Carl Setterberg(1882)
Isotopes of caesium
Main isotopes Decay abun­dance half-life(t1/2) mode pro­duct 131Cs synth 9.7 d ε 131Xe 133Cs 100% stable 134Cs synth 2.0648 y ε 134Xe β− 134Ba 135Cs trace 1.33×106y β− 135Ba 137Cs synth 30.17 y β− 137Ba

Angsesyoosesyum(Ingles:cesium,Kastila:cesio) ay isangelementong kimikalna mayatomikong bilangna 55 satalaang peryodikong mga elemento. Ito ay may simbolongCs.Bilang isang maypagka-alkalinang metal,mababa ang punto ng pagkatunaw nito (28 °C). Napakareaktibo nito o agad na tumutugon sa tubig. Mas marahas ang pagtugon nito sa tubig kaysa iba pang mgaalkalinang metal.Bilang resulta, iniimbak ang sesyo salangis na mineral.Isang bihirang elemento ang sesyo, at dahil kakaunti ang sesyo sa mundo, mahal ang halaga nito. Hindi kailangan ngkatawan ng taoang sesyo. Sa maramihang dami, bahagyang nakalalason ito dahil kagaya ito ngpotasyo,na hindi rin kailangan ng katawan ng tao.