Aluminum element symbol7/25/2023 To use electron affinities properly, it is essential to keep track of signs. Electron affinities are more difficult to measure than ionization energies.Īn atom of Aluminum in the gas phase, for example, gives off energy when it gains an electron to form an ion of Aluminum.Īl + e – → Al – – ∆H = Affinity = 42.5 kJ/mol Note that ionization energies measure the tendency of a neutral atom to resist the loss of electrons. In other words, it can be expressed as the neutral atom’s likelihood of gaining an electron. The change in energy (in kJ/mole) of a neutral atom or molecule (in the gaseous phase) when an electron is added to the atom to form a negative ion. In chemistry and atomic physics, the electron affinity of an atom or molecule is defined as: The Standard English unit is pounds mass per cubic foot ( lbm/ft 3).Įlectron Affinity and Electronegativity of AluminumĮlectron Affinity of Aluminum is 42.5 kJ/mol. ![]() ![]() The standard SI unit is kilograms per cubic meter ( kg/m 3). In other words, the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance. It is an intensive property, which is mathematically defined as mass divided by volume: Typical densities of various substances at atmospheric pressure.ĭensity is defined as the mass per unit volume. ![]() See also: Mass Number Density of Aluminum For 63Cu, the atomic mass is less than 63, so this must be the dominant factor. A nucleus with greater binding energy has lower total energy, and therefore a lower mass according to Einstein’s mass-energy equivalence relation E = mc 2.
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