potassium, cesium

potassium (chemical element) | cesium (chemical element)

Periodic table location

Images

| potassium | cesium atomic symbol | K | Cs atomic number | 19 | 55 short electronic configuration | [Ar]4s^1 | [Xe]6s^1 Aufbau diagram | 4s | 6s block | s | s group | 1 | 1 period | 4 | 6 atomic mass | 39.0983 u | 132.90545196 u half-life | (stable) | (stable)

| potassium | cesium phase at STP | solid | solid melting point | 63.38 °C | 28.44 °C boiling point | 759 °C | 671 °C critical temperature | 2223 K | 1938 K critical pressure | 16 MPa | 9.4 MPa molar heat of fusion | 2.33 kJ/mol | 2.09 kJ/mol molar heat of vaporization | 76.9 kJ/mol | 65 kJ/mol specific heat at STP | 757 J/(kg K) | 242 J/(kg K) (properties at standard conditions)

| potassium | cesium density | 0.856 g/cm^3 | 1.879 g/cm^3 liquid density | 0.828 g/cm^3 | 1.843 g/cm^3 molar volume | 45.7 cm^3/mol | 70.73 cm^3/mol Mohs hardness | 0.4 (between talc and gypsum) | 0.2 (between talc and gypsum) Brinell hardness | 0.363 MPa | 0.14 MPa bulk modulus | 3.1 GPa | 1.6 GPa shear modulus | 1.3 GPa | Young's modulus | | 1.7 GPa sound speed | 2000 m/s | thermal conductivity | 100 W/(m K) | 36 W/(m K) (properties at standard conditions)

| potassium | cesium electrical type | conductor | conductor resistivity | 7×10^-8 Ω m (ohm meters) | 2×10^-7 Ω m (ohm meters) electrical conductivity | 1.4×10^7 S/m (siemens per meter) | 5×10^6 S/m (siemens per meter) magnetic type | paramagnetic | paramagnetic volume magnetic susceptibility | 5.74×10^-6 | 5.26×10^-6 mass magnetic susceptibility | 6.7×10^-9 m^3/kg (cubic meters per kilogram) | 2.8×10^-9 m^3/kg (cubic meters per kilogram) molar magnetic susceptibility | 2.62×10^-10 m^3/mol (cubic meters per mole) | 3.72×10^-10 m^3/mol (cubic meters per mole) work function | 2.29 eV (Polycrystalline) | 1.95 eV (Polycrystalline) threshold frequency | 5.537×10^14 Hz (hertz) | 4.715×10^14 Hz (hertz) color | (silver) | (yellow)

| potassium | cesium valence | 1 | 1 electronegativity | 0.82 | 0.79 electron affinity | 48.4 kJ/mol (kilojoules per mole) | 45.5 kJ/mol (kilojoules per mole) first ionization energy | 418.8 kJ/mol (kilojoules per mole) | 375.7 kJ/mol (kilojoules per mole) ionization energies | 418.8 kJ/mol | 3052 kJ/mol | 4420 kJ/mol | 5877 kJ/mol | 7975 kJ/mol | 9590 kJ/mol | 11343 kJ/mol | 14944 kJ/mol | 16963.7 kJ/mol | 48610 kJ/mol | 375.7 kJ/mol | 2234.3 kJ/mol | 3400 kJ/mol

Reactivity

| potassium | cesium term symbol | ^2S_(1/2) | ^2S_(1/2) atomic radius | 220 pm | 260 pm covalent radius | 203 pm | 244 pm van der Waals radius | 275 pm | (electronic ground state properties)

| potassium | cesium universe abundance | 3×10^-4 mass% | 8×10^-8 mass% solar abundance | 4×10^-4 mass% | 8×10^-7 mass% meteorite abundance | 0.07 mass% | 1.4×10^-5 mass% crust abundance | 1.5 mass% | 1.9×10^-4 mass% ocean abundance | 0.042 mass% | 5×10^-8 mass% human abundance | 0.2 mass% | 2×10^-6 mass% universe molar abundance | 1×10^-5 mol% | 1×10^-9 mol% solar molar abundance | 9.9×10^-6 mol% | 7×10^-9 mol% meteorite molar abundance | 0.037 mol% | 2×10^-6 mol% ocean molar abundance | 0.0066 mol% | 2.3×10^-9 mol% crust molar abundance | 0.78 mol% | 2.9×10^-5 mol% human molar abundance | 0.032 mol% | 1×10^-7 mol%

| potassium | cesium half-life | (stable) | (stable) stable isotopes | K-39 (93.2581%) | K-41 (6.7302%) | Cs-133 (100%) nuclear spin | K-32: 1^+ | K-33: 3/2^+ | K-34: 1^+ | K-35: 3/2^+ | K-36: 2^+ | K-37: 3/2^+ | K-38: 3^+ | K-39: 3/2^+ | K-40: 4^- | K-41: 3/2^+ | K-42: 2^- | K-43: 3/2^+ | K-44: 2^- | K-45: 3/2^+ | K-46: 2^- | K-47: 1/2^+ | K-48: 2^- | K-49: 3/2^+ | K-52: 2^- | K-53: 3/2^+ | K-54: 2^- | K-55: 3/2^+ | Cs-113: 3/2^+ | Cs-114: 1^+ | Cs-115: 9/2^+ | Cs-116: 1^+ | Cs-117: 9/2^+ | Cs-118: 2^? | Cs-119: 9/2^+ | Cs-120: 2^+ | Cs-121: 3/2^+ | Cs-122: 1^+ | Cs-123: 1/2^+ | Cs-124: 1^+ | Cs-125: 1/2^+ | Cs-126: 1^+ | Cs-127: 1/2^+ | Cs-128: 1^+ | Cs-129: 1/2^+ | Cs-130: 1^+ | Cs-131: 5/2^+ | Cs-132: 2^+ | Cs-133: 7/2^+ | Cs-134: 4^+ | Cs-135: 7/2^+ | Cs-136: 5^+ | Cs-137: 7/2^+ | Cs-138: 3^- | Cs-139: 7/2^+ | Cs-140: 1^- | Cs-141: 7/2^+ | Cs-142: 0^- | Cs-143: 3/2^+ | Cs-144: 1^- | Cs-145: 3/2^+ | Cs-146: 1^- | Cs-147: 3/2^+ | Cs-149: 3/2^+ | Cs-151: 3/2^+ unstable isotopes | K-40 (1.248 Gyr) | K-43 (22.3 h) | K-42 (12.321 h) | K-44 (22.13 min) | K-45 (17.81 min) | K-38 (7.637 min) | K-46 (105 s) | K-47 (17.5 s) | K-48 (6.8 s) | K-49 (1.26 s) | K-37 (1.226 s) | K-50 (472 ms) | K-51 (365 ms) | K-36 (342 ms) | K-35 (178 ms) | K-52 (105 ms) | K-53 (30 ms) | K-54 (10 ms) | K-55 (3 ms) | K-34 (25 ns) | K-33 (25 ns) | Cs-135 (2.3 Myr) | Cs-137 (30.08 yr) | Cs-134 (2.0652 yr) | Cs-136 (13.04 days) | Cs-131 (9.689 days) | Cs-132 (6.479 days) | Cs-129 (32.06 h) | Cs-127 (6.25 h) | Cs-125 (46.7 min) | Cs-138 (33.42 min) | Cs-130 (29.22 min) | Cs-139 (9.27 min) | Cs-123 (5.87 min) | Cs-128 (220 s) | Cs-121 (155 s) | Cs-126 (98.4 s) | Cs-140 (63.7 s) | Cs-120 (61.2 s) | Cs-119 (43 s) | Cs-124 (30.9 s) | Cs-141 (24.84 s) | Cs-122 (21.18 s) | Cs-118 (14 s) | Cs-117 (8.4 s) | Cs-143 (1.791 s) | Cs-142 (1.684 s) | Cs-115 (1.4 s) | Cs-144 (0.994 s) | Cs-116 (700 ms) | Cs-145 (587 ms) | Cs-114 (570 ms) | Cs-146 (321 ms) | Cs-147 (235 ms) | Cs-148 (146 ms) | Cs-151 (50 ms) | Cs-150 (50 ms) | Cs-149 (50 ms) | Cs-112 (500 µs) | Cs-113 (16.7 µs) neutron cross-section | 2.1 b | 29 b neutron mass absorption | 0.0018 m^2/kg | 0.0077 m^2/kg

| potassium | cesium CAS number | 7440-09-7 | 7440-46-2 PubChem CID number | 5462222 | 5354618