Elements Of Life

• Why is the actual yield always less than the theoretical yield?

  The actual yield is always less than the theoretical yield due to:

  1. Incomplete reactions
  2. Unwanted side reactions
  3. Loss of product during transfer
• What is a co-product?


  Co-product is a product made alongside desired product.
• What is a by-product?

  By-product is a product formed in unwanted side reactions. e.g NOx in car exhausts
• What has the model for atomic structure evolved from?

  Knowledge and scientific understanding changes
• What does the current model of the atom consist of?

  A small nucleus surrounded by orbiting electrons

  
• When was the Rutherford scattering experiment conducted?

  In 1911
• What particles make up the nucleus of an atom?

  Protons and neutrons
• What charge does the nucleus of an atom have?

  Overall positive charge
• Where is most of the atom's mass located?

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

  They are equal in number
• How can the maximum number of orbiting electrons in a shell be calculated?

  Using the formula $2n^2$
• How many electrons can shell 2 hold?

  8 electrons
• What must happen before the next electron shell can hold electrons?

  The previous shell must be filled
• What does mass number (A) represent?

  Sum of protons and neutrons
• What does atomic number (Z) indicate?

  Number of protons in an atom
• 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 can the quantity of fundamental particles in an atom be calculated?

  Using atomic and mass numbers
• If an atom has an atomic number of 7 and a mass number of 14, how many neutrons does it have?


  7 neutrons
• What are ions?

  Atoms that lose or gain electrons
• What happens to the charge of an atom when it becomes an ion?

  It gains an overall charge
• How is the number of electrons in an ion calculated?

  Protons minus ionic charge
• How many electrons does Li⁺ have if it originally has 3 electrons?

  2 electrons
• What are isotopes?

  Atoms with the same atomic number but different neutrons
• How do neutral atoms of isotopes react chemically?

  They react the same way
• What affects the physical properties of isotopes?

  Different mass numbers
• What is the composition of Hydrogen in terms of protons and neutrons?

  1 proton and 1 neutron
• What is the composition of Deuterium?

  1 proton and 2 neutrons
• What is the composition of Tritium?

  1 proton and 3 neutrons
• What is Deuterium used for?

  To control nuclear processes
• How is relative atomic mass (Ar) defined?

  Weighted mean mass relative to carbon-12

  
• What does relative isotopic mass represent?

  Isotopic mass relative to carbon-12

  
• How is relative molecular mass (Mr) defined?

  Weighted mean mass of a molecule relative to carbon-12

  
• How can relative molecular mass be calculated?

  Add Ar values of component elements

  
• What is relative formula mass used for?

  For compounds with giant structures
• What does the amount of substance define?

  Number of particles in a substance