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 Magnesium 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. The nuclear binding energy varies between nuclei.This increases the mass of nuclei with more neutrons than protons relative to the atomic mass unit scale based on 12C with equal numbers of protons and neutrons. The neutron is slightly heavier than the proton.There are two reasons for the difference between mass number and isotopic mass, known as the mass defect: For example, 63Cu (29 protons and 34 neutrons) has a mass number of 63, and an isotopic mass in its nuclear ground state is 62.91367 u. The isotopic mass usually differs for other isotopes and is usually within 0.1 u of the mass number. One unified atomic mass unit is approximately the mass of one nucleon (either a single proton or neutron) and is numerically equivalent to 1 g/mol.įor 12C, the atomic mass is exactly 12u since the atomic mass unit is defined from it. One atomic mass unit is equal to 1.66 x 10 -24 grams.
The unit of measure for mass is the atomic mass unit (amu). Note that, each element may contain more isotopes, therefore this resulting atomic mass is calculated from naturally-occuring isotopes and their abundance. See also: Properties of Magnesium Atomic Mass of Magnesium Magnesium – Properties Element Magnesium Atomic Number 12 Symbol Mg Element Category Alkaline Earth Metal Phase at STP Solid Atomic Mass 24.305 Density at STP 1.738 Electron Configuration 3s2 Possible Oxidation States +2 Electron Affinity - Electronegativity 1.31 1st Ionization Energy 7.6462 Year of Discovery 1755 Discoverer Black, Joseph Thermal properties Melting Point 649 Boiling Point 1090 Thermal Conductivity 156 Specific Heat 1.02 Heat of Fusion 8.954 Heat of Vaporization 127.4 Magnesium is a shiny gray solid which bears a close physical resemblance to the other five elements in the second column (group 2, or alkaline earth metals) of the periodic table: all group 2 elements have the same electron configuration in the outer electron shell and a similar crystal structure. Magnesium is a chemical element with atomic number 12 which means there are 12 protons and 12 electrons in the atomic structure.
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