Atomic structure + formulae

• What is the first statement of Dalton's atomic theory?

  Atoms are tiny particles made of elements
• What does Dalton's atomic theory state about the divisibility of atoms?

  Atoms cannot be divided
• According to Dalton's atomic theory, what can be said about atoms in an element?

  All the atoms in an element are the same
• How does Dalton's atomic theory describe atoms of different elements?

  Atoms of one element are different from those of other elements
• What charge do electrons have according to Thompson's discovery?

  Electrons have a negative charge
• What can electrons be deflected by according to Thompson's discovery?

  Electrons can be deflected by magnet and electric field
• What is the mass of electrons as discovered by Thompson?

  Electrons have very small mass
• What is the plum pudding model of the atom?

  • Atoms are made up of negative electrons
  • Electrons move around in a sea of positive charge
• What did Rutherford propose about the location of mass and positive charge in the atom after the gold leaf experiment?

  Most of the mass and positive charge of the atom are in the nucleus
• According to Rutherford's proposal, where do electrons orbit?

  Electrons orbit the nucleus
• What does Rutherford's proposal state about the volume of the atom?

  Most of the atom's volume is the space between the nucleus and the electrons
• What must balance according to Rutherford's proposal?

  Overall positive and negative charges must balance
• What are the key features of the current model of the atom?

  • Protons and neutrons are found in the nucleus
  • Electrons orbit in shells
  • Nucleus is tiny compared to the total volume of the atom
  • Most of the atom's mass is in the nucleus
  • Most of the atom is empty space between the nucleus and the electrons
• What is the charge of a proton?

  1+
• What is the charge of an electron?

  1-
• Which particle has the same mass as a proton?

  Neutron
• Which two particles make up most of the atom's mass?

  Protons and neutrons
• Which letter is used to represent the atomic number of an atom?

  Z
• What does the atomic number tell about an element?

  Atomic number = number of protons in an atom
• Which letter represents the mass number?

  A
• How is mass number calculated?

  Mass number = number of protons + number of neutrons
• What is an isotope?

  Atoms of the same element with different number of neutrons
• Why do different isotopes of the same element react in the same way?

  Neutrons have no impact on the chemical reactivity
• How do you calculate the number of neutrons?

  Number of neutrons = mass number - atomic number
• What is the second reason why different isotopes of the same element react in the same way?

  Reactions involve electrons, isotopes have the same number of electrons in the same arrangement
• What are ions?

  Charged particles that are formed when an atom loses or gains electrons
• What is the charge of the ion when electrons are gained?

  Negative
• What is the charge of the ion when electrons are lost?

  Positive
• What is the unit used to measure atomic masses called?

  Unified atomic mass unit, u
• What is relative atomic mass?

  The weighted mean mass of an atom of an element compared with one twelfth of the mass of an atom of carbon-12
• What is the unit of relative atomic mass?

  No units
• What is relative isotopic mass?

  The mass of an atom of an isotope compared with one twelfth of the mass of an atom of carbon-12
• The relative isotopic mass is the same as which number?

  Mass number
• What assumptions are made when calculating atomic masses?

  • Atoms are indivisible
  • All atoms of a given element are identical
• What is the definition of relative atomic mass?

  The weighted mean mass of an atom of an element compared with one twelfth of the mass of an atom of carbon-12
• What is the definition of relative isotopic mass?

  The mass of an atom of an isotope compared with one twelfth of the mass of an atom of carbon-12
• What two assumptions are made when calculating mass number?

  1. Contribution of the electron is neglected; 2. Mass of both proton and neutron is taken as 1.0 u
• How do you calculate the relative molecular mass and relative formula mass?

  By adding the relative atomic masses of each of the atoms making up the molecule or the formula
• What are the uses of mass spectrometry?

  • Identify unknown compounds
  • Find relative abundance of each isotope of an element
  • Determine structural information
• How is the group number related to the number of electrons?

  Group number = number of electrons in the outer shell