paper 1 Q.s

• In modern periodic table , elements are arranged in order of

  Atomic / proton number
• Why did Mendeleev's periodic table become more widely accepted than previous versions?

  • Mendeleev predicted properties of undiscovered elements based on their position in the periodic table
  • Undiscovered elements filled the spaces
  • The properties of the elements matched mendeleevs predictions
• Describe what you would see when sodium reacts with chlorine

  • Flame
  • Solid forms
  • Color of gas / chlorine disappears / fades
• Explain why carbon nanotubes conduct electricity

  • Contains delocalised electrons
  • Electrons can move through structure

  
• Suggest one reason why it costs less to use nanoparticles rather than fine particles in sunscreen

  • Greater surface area ( to volume ratio)
  • Less can be used
• Define mass number

  The number of protons and neutrons in an elements
• Why is the mass number in isotopes different?

  Different numbers of neutrons
• Explain how evidence from the plum scattering experiment led to a change in the model of the atom

  • Most alpha particles passed straight through the gold foil
  • so the mass of the atom is concentrated in the centre/nucleus
  • so most of the atom is empty space
  • Some particles were deflected
  • So atom has a positively charged nucleus
• Why is electrolysis used to extract some metals?

  Those metals are more reactive than carbon
• Describe test for carbon dioxide

  Bubbling gas through limewater

  limewater turns milky
• Calcium hydroxide solution reacts with an acid to form calcium chloride

  word equation for the reaction

  Calcium hydroxide+hydrochloric acid -> calcium chloride+ water
• Explain why a mixture is used as the electrolyte instead of using only aluminium oxide

  • Mixture has a lower melting point
  • less energy needed
• What happens at the negative electrode during the production of aluminium

  Aluminium ions gain electrons
• Explain why the positive electrode must be continually replaced

  • Electrode reacts with oxygen
  • electrode is carbon/graphite
  • so carbon dioxide is produced
• explain why sodium chloride solution cannot be used as the electrolyte to produce sodium metal

  • Hydrogen would be produced
  • sodium more reactive than hydrogen