性質
選択した性質で化学元素を比較します。
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Atomic & electronic
- Atomic number Number of protons in the nucleus of an atom of each element. Defines the element’s identity and its place in the periodic table.
- Atomic weight (u) Standard atomic weight of an element — the weighted average over natural isotopes. Shown with the uncertainty or the natural-variation interval; for elements without a standard value the mass number of the selected isotope is listed separately.
- Atomic radius (pm) Characteristic size of an atom. Compared separately by measurement type — empirical, calculated, covalent, van der Waals and metallic radii are different quantities and must not be mixed.
- Electron configuration Arrangement of electrons over atomic orbitals in the ground state of the neutral atom — both the full configuration and the shorthand form.
- Electrons per shell & Bohr model Distribution of electrons over shells K, L, M and beyond for the neutral atom, with Bohr-model diagrams of every element.
- Valence electrons Number of electrons that can participate in chemical bonding, and how it follows from the element’s position in the periodic table.
- Ionization energies (eV) Successive energies required to remove electrons from a gaseous atom. Large jumps between successive steps indicate the start of a deeper shell.
- Protons, neutrons and electrons Composition of the neutral atom: protons and electrons equal the atomic number Z; the neutron count N = A − Z is given for the explicitly selected isotope with mass number A.
- Electron affinity (eV) Energy released when a neutral gaseous atom acquires a first electron. Positive values mean energy is released (the atom binds the extra electron).
- Ionic radius (pm) Radii of specific ions with their charge, coordination number and spin state. A single element has several ionic radii — there is no one universal value.
Chemical
- Electronegativity (Pauling scale) Tendency of an atom to attract bonding electrons, on the Pauling scale. Missing values are never replaced with zero.
- Oxidation states All known oxidation states of each element, with the most common ones highlighted. The summary counts how many elements exhibit each state.
- Valency & common ions Typical valences derived from common oxidation states, and the monatomic ions an element actually forms with their charges. Valency, ion charge and oxidation state are related but distinct quantities.
Physical
- Density (kg/m³) Density of the elemental substance under standard conditions, with separate rankings for gases and condensed phases.
- Melting point (K) Temperature at which the elemental substance melts at atmospheric pressure.
- Boiling point (K) Boiling temperature of the elemental substance at standard atmospheric pressure.
- Phase at STP & room temperature State of matter of the elemental substance at standard conditions (0 °C, 100 kPa). Counts of solid, liquid and gaseous elements are summarized below.
- Color & appearance How the elemental substance looks at room conditions: color, luster, transparency. Allotrope forms can differ.
- Crystal structure (pm) Crystal lattice type of the solid elemental substance, with lattice constant a where measured. Gases and liquids at these conditions are marked “not applicable”.
- Magnetic properties Dia-, para-, ferro- and other magnetic behavior of the elemental substance, with Curie/Néel temperatures where applicable. 開発中
Thermal & electrical
- Specific heat capacity (J/(g·K)) Heat capacity per unit mass (Cp) of the elemental substance at the reference temperature, with a separate molar mode.
- Thermal conductivity (W/(m·K)) Ability of the elemental substance to conduct heat at room conditions. The table doubles as a ranking of best and worst heat conductors.
- Electrical conductivity / resistivity Electrical conductivity in S/m and resistivity in Ω·m of the elemental substance, with temperature and form noted. 開発中
- Heat of fusion (eV) Enthalpy of fusion of the elemental substance at its melting point.
- Heat of vaporization (eV) Enthalpy of vaporization of the elemental substance at its boiling point.
Isotopes & abundance
- Isotopes Number of known and stable isotopes per element, with natural isotopes and their abundances listed in expandable rows.
- Radioactivity & half-life Whether an element has stable isotopes, and for the others the longest-lived known isotope with its half-life and decay mode. Half-life always belongs to an isotope, never to an element in general.
- Element abundance (mg/kg) How common each element is in a given environment. Modes are separate datasets and are never mixed.
Reference
- Group, period and block Position of each element in the periodic table: group, period and s/p/d/f block — the key to comparing electron structure.
- Element categories Metals, nonmetals, metalloids and finer categories such as alkali metals, halogens and noble gases. Boundaries between categories vary between sources; this site follows its catalog’s classification.
- Identifiers & data sources CAS Registry Numbers, InChI and InChIKey identifiers of the elemental substance, with links to external databases and an overview of data completeness.