Chapter 2

• Name all three subatomic particles

  Protons, Neutrons and Electrons
• How do chemists compare the masses of subatomic particles?

  They use relative masses.
• How do the masses of one Proton and one Neutron compare?

  Their mass is virtually the same. A Neutron is slightly heavier at 1.001375, this is so close to 1 that chemists usually assume both Protons and Neutrons have the same mass.
• How do the masses of one Proton and one Electron compare?

  An electron has about 1/1836th the mass of a Proton, meaning that 1836 Electrons have an equal mass to 1 Proton.
• What are the charges of a Proton, Neutron and Electron.

  A proton has a positive charge. A neutron has no charge, it is neutral. An Electron has a negative charge.
• What is the overall charge of an atom?

  0, it is neutral. The total positive charge from Protons is cancelled by the total negative charge from Electrons.
• Where does an atom hold nearly all of its mass?

  In the nucleus.
• Where can you find the number of Protons in an element on the periodic table?

  From its atomic number, sometimes known as its proton number.
• What is an isotope?

  Isotopes are atoms of the same element with different numbers of Neutrons and different masses.
• Most elements are made up of a mixture of isotopes' True or False?

  True
• What are the chemical notations used to represent isotopes?

  A = Mass Number or Nucleon Number (number of Protons and number of Neutrons)

  Z = Atomic Number (number of Protons)
• Is this table of the atomic structures for isotopes of Oxygen correct?

  Yes.

  
• What do chemical reactions involve?

  The Electrons surrounding the nucleus.
• Does the number of Neutrons have an effect on reactions of an element?

  No.
• Do different isotopes of the same element react the same?

  Yes because different isotopes of the same element have the same number of Electrons. It is only the Neutrons that are different, Neutrons have no effect on the reactions of an element.
• What can the small differences in physical properties be for higher-mass isotopes of an element?

  Higher-mass isotopes of an element can have higher melting point, boiling point and density.
• What is an ion?

  An ion is a charged atom.
• What makes an ion different to an isotope?

  It is the number of Electrons which is different from the number of Protons.

  An isotope has different numbers of Neutrons and different masses.
• What is a positive ion? What is it called?

  A positive ion has fewer Electrons than Protons. They are called Cations and have an overall positive charge.
• What is a negative ion? What is it called?

  A negative ion has more Electrons than Protons. They are called Anions and have an overall negative charge.
• What did Albert Einstein discover about the strong nuclear force holding together Protons and Neutrons?

  That the strong nuclear force holding them together comes at the expense of the loss of a fraction of their mass.
• What is the small amount of mass lost through a strong nuclear force holding together Protons and Neutrons called?

  The mass defect.
• What is the international standard for the measurement of atomic masses?

  The Carbon-12 isotope.
• What is the mass of one atom of Carbon-12?

  1.992646538x10 to the power of -26 kg.
• Working in kg would be very awkward. What is the new unit used instead called?

  It is called the Atomic Mass Unit (u).
• What is the mass of a Carbon-12 isotope defined as?

  The mass of a Carbon-12 isotope is defined as 12 atomic mass units (12u) exactly.
• What is the standard mass for atomic mass?

  The standard mass for atomic mass is 1u, 1/12th the mass of an atom of Carbon-12.
• On the scale of 1u being the standard mass for atomic mass, 1u is approximately the mass of a Proton or a Neutron' True or False?


  True.
• Define relative isotopic mass.

  Relative isotopic mass is the mass of an isotope relative to 1/12th of the mass of an atom of Carbon-12.
• Define relative atomic mass.

  Relative atomic mass, is the weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of Carbon-12.
• What is the chemical notation for relative atomic mass?

  Ar.
• What does the weighted mean mass take account of?

  The weighted mean mass takes account of the percentage abundance of each isotope as well as the relative isotopic mass of each isotope.
• What is used to find the percentage abundances of isotopes in a sample of an element?

  A mass spectrometer.
• What are the basic principles of a mass spectrometer?

  1. A sample is placed in the mass spectrometer

  2. The sample is vaporised and then ionised to form positive ions (cations)

  3. The ions are accelerated. Heavier ions move more slowly and are more difficult to deflect than lighter ions, separating the ions of each isotope.

  4. The ions are detected on a mass spectrum as a mass-to-charge ratio (m/z). Each ion reaching the detector adds to the signal, so the greater the abundance, the larger the signal.
• What is the mass-to-charge (m/z) ratio?


  Relative mass of ion OVER relative charge of ion (m/z).
• Is the ratio equivalent to the relative isotopic mass if an ion has one positive charge?

  Yes.
• Can a mass spectrometer also determine relative isotopic mass?

  Yes, a mass spectrometer can record the mass-to-charge (m/z) ratio of each isotope so that accurate values of relative isotopic mass can be measured.
• When ions are formed, electrons are either gained or lost in order to achieve what?

  Electrons are gained or lost to achieve the same electron structure as the nearest noble gas.
• Learn This

  All the elements in the highlighted columns have the same charge. It is good to know the charges of the highlighted elements off the top of your head.

  
• Do atoms of metals on the left of the periodic table gain or lose Electrons?

  Atoms of metals on the left of the periodic table lose Electrons to form Cations.