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Chemistry definition
Question | Answer |
---|---|
Atomic number | the X of an element is the number of protons in the nucleus of one atom of that element |
Relative atomic mass | The X of an element is the weighted average mass of an atom of that element divided by 1/12 the mass of a carbon-12 atom |
Relative molecular mass | The X of an element or compound is the average weighted mass of a molecule of that element or compound divided by 1/12 the mass of a carbon-12 atom |
Mass number of an isotope | The X of an element is the sum of the number of protons and neutrons in the nucleus of an atom of that isotope. |
Relative isotopic mass | The X is the mass of an atom of that element divided by 1/12 the mass of a carbon-12 atom |
Isotope | X are atoms of the same element that have the same number of protons but different number of neutrons. |
Electronegativity | The X of an element is the extent to which is attracts a pair of electrons in a covalent bond towards itself. |
First electron affinity | The X is the energy change when one electron is added to each atom in one mole of neutral gaseous atoms. |
Standard enthalpy change of reaction | The enthalpy change when the number of moles of the substance in the equation as written react under certain conditions of 1 atm pressure and a stated temperature, usually 298K. The units are kJ per mol. |
Standard enthalpy change of combustion | The enthalpy change when 1 mol of the substance is burnt in excess oxygen under standard conditions of 1 atm pressure and a stated temp of usually 298K. The units are kJ per mol. |