Chemistry Definitions 0.0 / 5 ? ChemistryBasic ideas about atoms and calculation definitionsASWJEC Created by: Sophia DowdenCreated on: 16-05-16 10:24 The number of protons in the nucleus of an atom Atomic Number 1 of 17 The total number of protons plus neutrons in the nucleus of an atom Mass Number 2 of 17 Atoms of the same element, with the same number of protons and electrons but different numbers of neutrons Isotopes 3 of 17 The emission of 2 protons and 2 neutrons (a He nucleus) from an unstable nucleus Alpha Decay 4 of 17 A neutron changes to a proton and an electron. The electron is then emitted. Beta Decay 5 of 17 Short wavelength, high energy electromagnetic radiation Gamma decay 6 of 17 The time taken for half the radioactive nuclei to decay Half-life 7 of 17 A region of space where an electron is likely to be found Orbital 8 of 17 The amount of energy required to remove the outermost elelctron from each gaseous atom in one mole to create uni-positive ions First Ionisation energy 9 of 17 The average mass of an atom compared to 1/12th the mass of an atom of C-12 Relative atomic mass 10 of 17 The mass of an atom compared to 1/12th the mass of an atom of C-12 Relative Isotopic Mass 11 of 17 The average mass of a molecule relative to 1/12th the mass of an atom of C-12 Relative molecular mass 12 of 17 The average mass of one formula unit relative to 1/12th the mass of an atom of C-12 Relative formula mass 13 of 17 An amount of substance that contains the smae number of particles as there are atoms in exactly 12g of C-12 Mole 14 of 17 The number of particles in one mole of a substance: 6.02 x 10(^23) Avogardo's constant 15 of 17 The simplest whole number ratio of atoms of each element present in a compound Empirical formula 16 of 17 The actual number of atoms of each element present in a molecule/formula unit of a compound Molecular formula 17 of 17
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