Module 2: Atomic structure and isotopes

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  • Created by: clarke148
  • Created on: 21-04-16 16:05
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  • Atoms, Ions and Compounds
    • nucleus contains subatomic particles: protons and neutrons
      • Electrons are arranged around the nucleus in shells
    • The mass of a proton and neutron = 1 An electrons mass is = 1/1836
    • Atoms contain the same number of protons as electrons
    • The charge of a proton is +1 a neutron is 0 and an electron is -1
    • Nearly all of the atoms mass is in the nucleus
    • The total positive charge from protons is cancelled by the total negative charge of electrons
      • The overall charge of the atom is zero
  • Atomic number
    • The identity of an element: the number of protons in an element
    • Every atom of the same element contains the same number of protons
    • Different elements contain atoms that have different numbers of protons
    • Atoms, Ions and Compounds
      • nucleus contains subatomic particles: protons and neutrons
        • Electrons are arranged around the nucleus in shells
      • The mass of a proton and neutron = 1 An electrons mass is = 1/1836
      • Atoms contain the same number of protons as electrons
      • The charge of a proton is +1 a neutron is 0 and an electron is -1
      • Nearly all of the atoms mass is in the nucleus
      • The total positive charge from protons is cancelled by the total negative charge of electrons
        • The overall charge of the atom is zero
    • The periodic table lists elements in order of the number of protons  in the nucleus
  • Isotopes
    • Every atom of an element has the same number of protons
    • Isotopes are atoms of the same element with different numbers of neutrons
      • They have different masses
    • Most elements are made up of a mixture of elements
    • Representing Isotopes
      • Mass number =A
        • A= number of protons + number of neutrons
      • Atomic number = z
        • z = to the number of protons
    • Different isotopes of the same element have the same number of electrons
    • The number of neutrons has no effect on reactions of an element
      • Different isotopes of an element therefore react in the same way
        • Physical properties: with higher -mass isotopes of an element having higher boiling points, melting points and densities
  • Atomic structure of ions
    • An ion is a charged atom
    • Positive ions are cations, are atoms wih fewer electrons than protons
      • cations have an overall positive charge
    • Negative ions are anions, are atoms with more electrons than protons
      • Anions have an overall negative charge
    • Mg2+ has 2 fewer electrons than protons
      • Cl- has one more electron than portons
    • Ions and atoms of an element have the same number of protons but different number of electrons

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