2.1.1 Atomic structure, Isotopes, 2.12 Compounds, formulae

• What is the atomic number?

  The number of protons in the nucleus of an atom
• What is the bohr model?

  The bohr model describes an atom as a small dense nucleus with electrons orbiting around the nucleus. This model explains different periodic properties of atoms.
• What is an electron?

  A negatively charged subatomic particle which orbits the nucleus at various energy levels. The relative mass is negligable.
• What is an ion?

  A charged atom or molecule.
• What is an isotope?

  An isotope is a variant of an element that has the same number of protons but a different number of neutrons in its nucleus.
• What is the mass number?

  The total number of protons and neutrons in the nucleus of an atom
• What is mass spectrometry?

  An instrument which gives accurate information about relative isotopic

  mass and the relative abundance of isotopes.
• What is a neutron?

  A neutral subatomic particle found in the nucleus of an atom. The relative mass of a neutron is 1
• What is a proton?

  A positively charged subatomic particle found in the nucleus of an atom. The relative mass of a proton is 1
• What is relative abundance?

  the amount of one substance compared with another.
• What is the relative atomic mass?

  The weighted average mass of an element's isotopes.
• What is the relative isotopic mass?

  The sum of the masses of the isotopes of an element, weighted by their relative abundance.
• What is the relative formula mass?

  The sum of the atomic masses of all the atoms in a chemical formula.
• What is the relative molecular mass?

  The sum of the atomic masses of all the atoms in a molecule.
• What is an ionic compound?

  a compound which is made up of oppositely charged ions that are held

  together by electrostatic forces.