Chem

• Atomic number


  The number of protons in the nucleus of an atom.

  Atomic number = number of protons = number of electrons
• Isotope


  Atoms of an element with the same atomic number but a different mass number, indicating a different number of neutrons.
• Mass number


  The total number of protons and neutrons in the nucleus of an atom
• Cation


  A positively charged ion formed when a metal atom loses one or more electrons
• Protons


  Positively charged particles in the nucleus of an atom
• Anion

  A negatively charged ion formed when a non-metal atom gains one or more electrons
• Neutrons


  Neutral particles in the nucleus of an atom
• Electrostatic


  Relating to stationary electric charges and the forces between them
• Electrons


  Negatively charged particles that orbit the nucleus of an atom
• Atom


  The smallest part of an element that can exist on its own. Inside are smaller, sub-atomic particles.

  Atoms are neutral.
• Ionic bonding


  A metal atom transfers electrons to non-metals so both have a full outer shell
• Ionic bonding


  • Sodium chloride
• Atoms contain protons, neutrons and electrons
• Atomic structure components


  • Proton
  • Electron
  • Neutron
• Atoms are electrically neutral as they contain the same number of positive protons and negative electrons
• Atomic number


  Tells the number of protons (and in an atom, the number of electrons)
• Mass number


  Tells the number of protons AND the number of neutrons
• John Dalton proposed that atoms were the smallest particles
• J.J. Thomson proposed the plum pudding model where electrons were embedded in a positive sphere
• Rutherford proposed planetary model where electrons orbit a central nucleus containing positive protons and an unknown particle
• Chadwick discovered the neutron (difficult to discover as it has no charge)
• Isotopes


  Atoms of the same element with the same number of protons but a different number of neutrons
• Isotopes of chlorine


  • C135
  • C137
• The atomic number will always be the same for isotopes, but the mass number will be different from the Periodic Table
• Electronic configuration of atoms

  • First shell holds max. 2 electrons
  • Second shell holds max. 8 electrons
  • Third shell holds max. 8 electrons
• Magnesium needs to lose 2 electrons and chlorine needs to gain 1 electron
• Magnesium transfers 2 electrons to 2 atoms of chlorine (each atom receives 1 electron)
• Magnesium ion has a full outer shell and a charge of 2+, each chloride ion has a full outer shell and a charge of 1-
• Positive Mg2+ attracts negative Cl-
• Ionic lattice


  Ions regularly arranged in a giant structure
• We can use the % abundance to work out the Relative Atomic Mass (RAM) of chlorine
• Relative Atomic Mass (RAM)


  All atoms are measured relative to the mass of an atom of carbon-12
• Cation


  A positively charged ion formed when an atom loses electrons
• Anion


  A negatively charged ion formed when an atom gains electrons
• Atoms will lose or gain electrons to get a full outer shell (like a Noble Gas)
• Bonding pair


  A pair of shared electrons in a covalent bond
• Lone pair


  A pair of unshared electrons in a covalent bond
• Covalent bond


  A chemical bond formed by the sharing of one or more pairs of electrons between atoms
• Diatomic


  A molecule consisting of two atoms
• Van der Waals forces


  Weak intermolecular forces between molecules