Atomic Structure

• What happens to the model for atomic structure as scientific understanding evolves?

  It changes over time
• According to the Plum Pudding Model, what did atoms consist of?

  A sphere of positive charge
• According to the Plum Pudding Model, where were the negative charges located?

  Distributed evenly within the positive charge
• What does the modern electron shell model say that atoms consist of?

  A small, dense central nucleus
• In the electron shell model, what surrounds the nucleus?

  Orbiting electrons in electron shells
• When was the electron shell model of the atom discovered?

  1911
• What experiment led to the discovery of the electron shell model?

  Rutherford scattering experiment
• What is the overall charge of the nucleus?

  Positive
• What particles make up the nucleus of an atom?

  Protons and neutrons
• Where is almost all the mass of the atom located?

  In the nucleus
• In a neutral atom, what is the relationship between the number of electrons and protons?

  They are equal
• What is the relative charge of a proton?

  +1
• What is the relative charge of a neutron?

  0
• What is the relative charge of an electron?

  -1
• What is the relative mass of a proton?

  1
• What is the relative mass of a neutron?

  1
• What is the relative mass of an electron?

  1/1840
• How is the maximum number of electrons in a shell calculated, where n is the shell number?

  $2n^2$
• How many electrons can be held in the 3rd electron shell?

  18
• What condition must be met before the next electron shell can hold any electrons?

  Each electron shell must fill
• What symbol is used to represent mass number?

  A
• How is the mass number calculated?

  Sum of protons and neutrons
• What symbol is used to represent atomic number?

  Z
• What is the atomic number equal to?

  The number of protons
• If an atom has an atomic number of 6 and a mass number of 12, how many neutrons does it have?

  6
• What is the symbol for relative atomic mass?

  Ar

  
• What is relative atomic mass defined as?

  Mean mass of an atom divided by one-twelfth of carbon-12
• What factor does relative atomic mass take into account?

  Relative abundances of isotopes
• What are isotopes?

  Atoms of the same element with different neutron numbers
• What is the same between isotopes of an element?

  Atomic number
• What is different between isotopes of an element?

  Number of neutrons
• What is different between isotopes of an element?

  Mass number
• How do neutral atoms of isotopes react chemically?

  They react in the same way
• Why do isotopes react chemically in the same way?

  Same proton number and electron configuration
• Which property differs among isotopes?

  Physical properties
• How are ions formed?

  By losing or gaining electrons
• What is the overall charge of an ion?

  A non-zero charge
• What type of technique is Mass Spectrometry?

  Analytical technique
• What is mass spectrometry used for?

  To identify isotopes and find relative atomic mass
• What does TOF stand for in Time of Flight Mass Spectrometry?

  Time of Flight