quantative chem

• What are the main components of an atom?

  Protons, neutrons, and electrons
• Why is the mass of an atom primarily due to protons and neutrons?

  Because the mass of an electron is negligible in comparison
• 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?

  1/2000
• What does the atomic number of an element represent?

  The number of protons in the nucleus of an atom
• What are isotopes?

  Atoms of the same element with different numbers of neutrons
• How many protons does chlorine have?

  17
• What is the relative atomic mass (Ar)?

  The average mass of one atom of an element relative to 1/12th of the mass of carbon-12
• What is the relative atomic mass of hydrogen (H)?

  1
• What is the relative atomic mass of carbon (C)?

  12
• What is the relative atomic mass of nitrogen (N)?

  14
• What is the relative atomic mass of oxygen (O)?

  16
• What is the relative atomic mass of sodium (Na)?

  23
• What is the relative atomic mass of aluminum (Al)?

  27
• What is the relative atomic mass of sulfur (S)?

  32
• What is the relative atomic mass of chlorine (Cl)?

  35.5
• What is the relative atomic mass of copper (Cu)?

  64
• How can the relative atomic mass of an element be calculated?

  By considering its isotopes and their abundances
• What is the relative atomic mass of Brewisium (Bw) with 3% Brewisium-29 and 97% Brewisium-31?

  30.94
• What is the relative formula mass (Mr)?

  The mass of one formula unit of a compound relative to 1/12th of the mass of carbon-12
• How do you calculate the relative formula mass of Cu(NO3)2?

  188
• When should the term 'Relative Molecular Mass' be used?

  When dealing with simple covalent compounds
• What are the three main subatomic particles that make up an atom?

  Protons, neutrons, and electrons
• What is the relative mass and charge of a proton, neutron, and electron?

  Proton: Relative mass = 1, Relative charge = +1; Neutron: Relative mass = 1, Relative charge = 0; Electron: Relative mass = 1/2000, Relative charge = -1
• What is the difference between isotopes?

  Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons
• Why is a relative scale used to measure atomic masses?

  Because the mass of any atom is so very small, it is impractical to measure it in conventional units, so a relative scale is used with one atom of carbon-12 defined as having a mass of 12 units
• What is the relative atomic mass (Ar) of an element?

  The average mass of one atom of an element, relative to 1/12th of the mass of one atom of carbon-12
• How do you calculate the relative atomic mass (Ar) of an element with multiple isotopes?

  Ar = (percentage of isotope 1 x mass of isotope 1) + (percentage of isotope 2 x mass of isotope 2) + ...
• What is the relative formula mass (Mr) of a compound?

  The mass of one formula unit of a compound, relative to 1/12th of the mass of one atom of carbon-12
• How do you calculate the relative formula mass (Mr) of a compound?


  Mr = sum of the relative atomic masses of all the atoms in the compound's formula
• What is the percentage by mass of an element in a compound?

  The percentage of the total mass of the compound that is accounted for by that element
• How do you calculate the percentage by mass of an element in a compound?

  Percentage by mass = (total mass of that element / total mass of the compound) x 100%
• What is the mole?


  The amount of substance which contains the Avogadro constant of a specified particle or formula unit
• What is the Avogadro constant and what does it represent?

  The Avogadro constant is equal to the number of atoms in 12g of carbon-12, which is approximately 6.02 x 10^23
• What is the molar mass of a substance?


  The mass of one mole of a substance, which is numerically equal to the formula mass of the substance
• How do you calculate the amount of a substance in moles given its mass and molar mass?

  Amount of substance (mol) = mass (g) / molar mass (g/mol)
• What is the difference between the empirical formula and molecular formula of a compound?

  The empirical formula is the simplest whole-number ratio of atoms in a compound, while the molecular formula is the actual number of each type of atom in one molecule of the compound
• How do you determine the molecular formula of a compound from its empirical formula and relative molecular mass?

  The molecular formula must be a whole number multiple of the empirical formula such that the relative molecular mass is a whole number multiple of the empirical formula mass
• What are the general steps to solve reacting masses problems in chemistry?

  1. Use the information given to find the number of moles of one substance
  2. Write a balanced equation for the reaction
  3. Use the balanced equation to find the number of moles of the substance you are asked about
  4. Convert the moles to the required mass or volume