3. Atomic structure

• What is an atom?


  It is the smallest particle that can still have the same characteristics of an element
• What is the arrangement of an atom?

  
• Where are protons and neutrons found?

  In the nucleus (Nucleon number/mass number)
• Where is the mass of an atom most predominantly determined? Why?

  In the nucleus. The nucleus contains protons and neutrons which are far heavier than the mass of electrons. Thus, the mass of the electrons become insignificant
• How are electrons arranged?


  Arranged in electron shells, spaced further away from the nucleus and moving rapidly
• What is the charge of an atom? Why?

  Always electrically neutral. The number of protons, with a positive charge, is always the same as the number of electrons, which are negatively charged
• What is the atomic number?

  Number of proton in an atom
• What are isotopes?

  They are atoms of the same element with the same number of protons but different number of neutrons
• What is the property of isotopes?

  • Isotopes of the same element have the same chemical properties
  • They form compounds with the same formula but have slightly different properties
• Why do isotopes have same chemical properties as the atoms of its element?

  Since only valence electrons are involved in chemical reactions, isotopes will have the same chemical properties since they have the same number of valence electrons
• What are the physical differences isotopes have compared to an atom of its element?


  • Different densities
  • Different melting and boiling point
• Why do isotopes have different physical properties compared to the atoms of its element?

  Isotopes have a different relative atomic mass
• What is the chemical properties dependent on in an atom?

  The number of valence electrons