group 1 elements

alkali metals

lithium | sodium | potassium | rubidium | cesium | francium (total: 6)

Periodic table location

Images

| atomic symbol | atomic number | short electronic configuration lithium | Li | 3 | [He]2s^1 sodium | Na | 11 | [Ne]3s^1 potassium | K | 19 | [Ar]4s^1 rubidium | Rb | 37 | [Kr]5s^1 cesium | Cs | 55 | [Xe]6s^1 francium | Fr | 87 | [Rn]7s^1 | Aufbau diagram | block | group lithium | 2s | s | 1 sodium | 3s | s | 1 potassium | 4s | s | 1 rubidium | 5s | s | 1 cesium | 6s | s | 1 francium | 7s | s | 1 | period | atomic mass | half-life lithium | 2 | 6.94 u | (stable) sodium | 3 | 22.98976928 u | (stable) potassium | 4 | 39.0983 u | (stable) rubidium | 5 | 85.4678 u | (stable) cesium | 6 | 132.90545196 u | (stable) francium | 7 | 223 u | 22 min

phase at STP | all | solid melting point | median | 63.38 °C | highest | 180.54 °C (lithium) | lowest | 28.44 °C (cesium) | distribution | boiling point | median | 759 °C | highest | 1342 °C (lithium) | lowest | 671 °C (cesium) | distribution | critical temperature | median | 2223 K | highest | 3223 K (lithium) | lowest | 1938 K (cesium) | distribution | critical pressure | median | 16 MPa | highest | 67 MPa (lithium) | lowest | 9.4 MPa (cesium) | distribution | molar heat of fusion | median | 2.26 kJ/mol | highest | 3 kJ/mol (lithium) | lowest | 2 kJ/mol (francium) | distribution | molar heat of vaporization | median | 74 kJ/mol | highest | 147 kJ/mol (lithium) | lowest | 65 kJ/mol (cesium and francium) | distribution | specific heat at STP | median | 757 J/(kg K) | highest | 3570 J/(kg K) (lithium) | lowest | 242 J/(kg K) (cesium) | distribution | (properties at standard conditions)

density | median | 0.968 g/cm^3 | highest | 1.879 g/cm^3 (cesium) | lowest | 0.535 g/cm^3 (lithium) liquid density | median | 0.927 g/cm^3 | highest | 1.843 g/cm^3 (cesium) | lowest | 0.512 g/cm^3 (lithium) | distribution | molar volume | median | 45.7 cm^3/mol | highest | 70.73 cm^3/mol (cesium) | lowest | 13 cm^3/mol (lithium) | distribution | Mohs hardness | median | 0.4 | highest | 0.6 (between talc and gypsum) (lithium) | lowest | 0.2 (between talc and gypsum) (cesium) | distribution | Brinell hardness | all | 0.14 MPa | 0.216 MPa | 0.363 MPa | 0.69 MPa bulk modulus | median | 3.1 GPa | highest | 11 GPa (lithium) | lowest | 1.6 GPa (cesium) | distribution | shear modulus | median | 3.3 GPa | highest | 4.2 GPa (lithium) | lowest | 1.3 GPa (potassium) | distribution | Young's modulus | median | 3.7 GPa | highest | 10 GPa (sodium) | lowest | 1.7 GPa (cesium) | distribution | ultimate tensile strength | all | 10 MPa | 15 MPa sound speed | median | 2600 m/s | highest | 6000 m/s (lithium) | lowest | 1300 m/s (rubidium) | distribution | thermal conductivity | median | 85 W/(m K) | highest | 140 W/(m K) (sodium) | lowest | 36 W/(m K) (cesium) | distribution | (properties at standard conditions)

resistivity | median | 9.4×10^-8 Ω m (ohm meters) | highest | 2×10^-7 Ω m (ohm meters) (cesium) | lowest | 4.7×10^-8 Ω m (ohm meters) (sodium) | distribution | electrical conductivity | median | 1.1×10^7 S/m (siemens per meter) | highest | 2.1×10^7 S/m (siemens per meter) (sodium) | lowest | 5×10^6 S/m (siemens per meter) (cesium) | distribution | volume magnetic susceptibility | median | 5.74×10^-6 | highest | 1.37×10^-5 (lithium) | lowest | 3.98×10^-6 (rubidium) | distribution | mass magnetic susceptibility | median | 6.7×10^-9 m^3/kg (cubic meters per kilogram) | highest | 2.56×10^-8 m^3/kg (cubic meters per kilogram) (lithium) | lowest | 2.6×10^-9 m^3/kg (cubic meters per kilogram) (rubidium) molar magnetic susceptibility | median | 2.22×10^-10 m^3/mol (cubic meters per mole) | highest | 3.72×10^-10 m^3/mol (cubic meters per mole) (cesium) | lowest | 1.78×10^-10 m^3/mol (cubic meters per mole) (lithium) | distribution | work function | all | 1.95 eV | 2.26 eV | 2.29 eV | 2.36 eV | 2.93 eV

valence | median | 1 | highest | 1 (6 elements) | lowest | 1 (6 elements) electronegativity | median | 0.82 | highest | 0.98 (lithium) | lowest | 0.7 (francium) | distribution | electron affinity | median | 48.4 kJ/mol (kilojoules per mole) | highest | 59.6 kJ/mol (kilojoules per mole) (lithium) | lowest | 45.5 kJ/mol (kilojoules per mole) (cesium) | distribution | first ionization energy | median | 410.9 kJ/mol (kilojoules per mole) | highest | 520.2 kJ/mol (kilojoules per mole) (lithium) | lowest | 375.7 kJ/mol (kilojoules per mole) (cesium) | distribution |

term symbol | all | ^2S_(1/2) atomic radius | median | 220 pm | highest | 260 pm (cesium) | lowest | 145 pm (lithium) | distribution | covalent radius | median | 212 pm | highest | 260 pm (francium) | lowest | 128 pm (lithium) | distribution | van der Waals radius | median | 227 pm | highest | 275 pm (potassium) | lowest | 182 pm (lithium) | distribution | (electronic ground state properties)