potassium vs sodium vs rubidium

potassium (chemical element) | sodium (chemical element) | rubidium (chemical element)

Periodic table location

Images

| potassium | sodium | rubidium atomic symbol | K | Na | Rb atomic number | 19 | 11 | 37 short electronic configuration | [Ar]4s^1 | [Ne]3s^1 | [Kr]5s^1 Aufbau diagram | 4s | 3s | 5s block | s | s | s group | 1 | 1 | 1 period | 4 | 3 | 5 atomic mass | 39.0983 u | 22.98976928 u | 85.4678 u half-life | (stable) | (stable) | (stable)

| potassium | sodium | rubidium phase at STP | solid | solid | solid melting point | 63.38 °C | 97.72 °C | 39.31 °C boiling point | 759 °C | 883 °C | 688 °C critical temperature | 2223 K | 2573 K | 2093 K critical pressure | 16 MPa | 35 MPa | 16 MPa molar heat of fusion | 2.33 kJ/mol | 2.6 kJ/mol | 2.19 kJ/mol molar heat of vaporization | 76.9 kJ/mol | 97.7 kJ/mol | 72 kJ/mol specific heat at STP | 757 J/(kg K) | 1230 J/(kg K) | 364 J/(kg K) (properties at standard conditions)

| potassium | sodium | rubidium density | 0.856 g/cm^3 | 0.968 g/cm^3 | 1.532 g/cm^3 liquid density | 0.828 g/cm^3 | 0.927 g/cm^3 | 1.46 g/cm^3 molar volume | 45.7 cm^3/mol | 23.7 cm^3/mol | 55.79 cm^3/mol Mohs hardness | 0.4 (between talc and gypsum) | 0.5 (between talc and gypsum) | 0.3 (between talc and gypsum) Brinell hardness | 0.363 MPa | 0.69 MPa | 0.216 MPa bulk modulus | 3.1 GPa | 6.3 GPa | 2.5 GPa shear modulus | 1.3 GPa | 3.3 GPa | Young's modulus | | 10 GPa | 2.4 GPa ultimate tensile strength | | 10 MPa | sound speed | 2000 m/s | 3200 m/s | 1300 m/s thermal expansion | | 7.1×10^-5 K^(-1) | thermal conductivity | 100 W/(m K) | 140 W/(m K) | 58 W/(m K) (properties at standard conditions)

| potassium | sodium | rubidium electrical type | conductor | conductor | conductor resistivity | 7×10^-8 Ω m (ohm meters) | 4.7×10^-8 Ω m (ohm meters) | 1.2×10^-7 Ω m (ohm meters) electrical conductivity | 1.4×10^7 S/m (siemens per meter) | 2.1×10^7 S/m (siemens per meter) | 8.3×10^6 S/m (siemens per meter) magnetic type | paramagnetic | paramagnetic | paramagnetic volume magnetic susceptibility | 5.74×10^-6 | 8.5×10^-6 | 3.98×10^-6 mass magnetic susceptibility | 6.7×10^-9 m^3/kg (cubic meters per kilogram) | 8.8×10^-9 m^3/kg (cubic meters per kilogram) | 2.6×10^-9 m^3/kg (cubic meters per kilogram) molar magnetic susceptibility | 2.62×10^-10 m^3/mol (cubic meters per mole) | 2×10^-10 m^3/mol (cubic meters per mole) | 2.22×10^-10 m^3/mol (cubic meters per mole) work function | 2.29 eV (Polycrystalline) | 2.36 eV (Polycrystalline) | 2.26 eV (Polycrystalline) threshold frequency | 5.537×10^14 Hz (hertz) | 5.706×10^14 Hz (hertz) | 5.467×10^14 Hz (hertz) color | (silver) | (silver) | (silver)

| potassium | sodium | rubidium valence | 1 | 1 | 1 electronegativity | 0.82 | 0.93 | 0.82 electron affinity | 48.4 kJ/mol (kilojoules per mole) | 52.8 kJ/mol (kilojoules per mole) | 46.9 kJ/mol (kilojoules per mole) first ionization energy | 418.8 kJ/mol (kilojoules per mole) | 495.8 kJ/mol (kilojoules per mole) | 403 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 | 495.8 kJ/mol | 4562 kJ/mol | 6910.3 kJ/mol | 9543 kJ/mol | 13354 kJ/mol | 16613 kJ/mol | 20117 kJ/mol | 25496 kJ/mol | 28932 kJ/mol | 141362 kJ/mol | 403 kJ/mol | 2633 kJ/mol | 3860 kJ/mol | 5080 kJ/mol | 6850 kJ/mol | 8140 kJ/mol | 9570 kJ/mol | 13120 kJ/mol | 14500 kJ/mol | 26740 kJ/mol

Reactivity

| potassium | sodium | rubidium term symbol | ^2S_(1/2) | ^2S_(1/2) | ^2S_(1/2) atomic radius | 220 pm | 180 pm | 235 pm covalent radius | 203 pm | 166 pm | 220 pm van der Waals radius | 275 pm | 227 pm | (electronic ground state properties)

| potassium | sodium | rubidium universe abundance | 3×10^-4 mass% | 0.002 mass% | 1×10^-6 mass% solar abundance | 4×10^-4 mass% | 0.004 mass% | 3×10^-6 mass% meteorite abundance | 0.07 mass% | 0.55 mass% | 3.2×10^-4 mass% crust abundance | 1.5 mass% | 2.3 mass% | 0.006 mass% ocean abundance | 0.042 mass% | 1.1 mass% | 1.2×10^-5 mass% human abundance | 0.2 mass% | 0.14 mass% | 4.6×10^-4 mass% universe molar abundance | 1×10^-5 mol% | 1×10^-4 mol% | 1×10^-8 mol% solar molar abundance | 9.9×10^-6 mol% | 2×10^-4 mol% | 4×10^-8 mol% meteorite molar abundance | 0.037 mol% | 0.48 mol% | 7.8×10^-5 mol% ocean molar abundance | 0.0066 mol% | 0.3 mol% | 8.7×10^-7 mol% crust molar abundance | 0.78 mol% | 2.1 mol% | 0.0014 mol% human molar abundance | 0.032 mol% | 0.038 mol% | 3.4×10^-5 mol%