atomic structure & periodic table

• What are atoms the smallest part of?

  An element
• What does the chemical symbol Na represent?

  An atom of sodium
• How are compounds formed?

  • Formed from elements by chemical reactions
  • Involve formation of new substances
  • Often involve an energy change
• What do compounds contain?

  Two or more elements chemically combined
• How can compounds be represented?

  By formulae using chemical symbols
• What is the formula for hydrochloric acid?

  HCl
• How can compounds be separated into elements?

  Only by chemical reactions
• What is a mixture?

  • Consists of two or more substances
  • Not chemically combined
  • Chemical properties of substances remain unchanged
• How can mixtures be separated?

  By physical processes
• What are the methods to separate mixtures?

  • Filtration
  • Crystallisation
  • Simple distillation
  • Fractional distillation
  • Chromatography
• What was the first model of the atom thought to be?

  Tiny spheres that could not be divided
• What did the plum pudding model propose?

  Atom is a ball of positive charge
• What did the alpha particle scattering experiment conclude?

  Mass of an atom is concentrated at the nucleus
• What was aimed at thin gold foil in the scattering experiment?

  A beam of alpha particles
• What happened to some alpha particles in the experiment?

  They were deflected at different angles
• Who suggested that electrons orbit the nucleus?

  Neil Bohr
• What did later experiments reveal about the nucleus?

  It can be subdivided into protons
• Who provided evidence for neutrons in the nucleus?

  James Chadwick
• What is the atomic number?

  Number of protons in an atom
• What is the relative charge of a proton?

  +1
• Do all atoms of a particular element have the same number of protons?

  Yes
• What is the relative charge of a neutron?

  0
• What is the relative charge of an electron?

  • 1
• What is the overall charge of an atom?

  0
• What is the radius of an atom approximately?

  0.1 nm
• How does the radius of a nucleus compare to that of an atom?

  Less than 1/10,000 of that of the atom
• What is the mass number?

  Sum of protons and neutrons
• What are isotopes?

  Atoms of the same element with different neutrons
• What is relative atomic mass?

  Average value considering isotope abundance
• How do you calculate the relative atomic mass of carbon with isotopes?

  Use the formula: ((isotope 1 mass x abundance) + (isotope 2 mass x abundance)) ÷ 100
• What is the relative atomic mass of carbon with isotopes carbon-14 (20%) and carbon-12 (80%)?

  12.4
• What is the electronic structure of an atom?

  • Tells how many electrons are in each shell
  • Electrons occupy lowest available energy levels
  • Example for sodium: 2, 8, 1
• How many electrons are in shell 1 for sodium?

  2 electrons
• How many electrons are in shell 2 for sodium?

  8 electrons
• How many electrons are in shell 3 for sodium?

  1 electron
• How do transition elements compare to group 1 elements in terms of hardness and strength?

  They are harder and stronger
• What is a notable exception regarding the melting points of transition elements?

  Mercury has a lower melting point
• Why are transition elements considered less reactive than group 1 elements?

  They react much less vigorously with oxygen or water
• What are the typical properties of transition elements?

  • Ions with many different charges
  • Form coloured compounds
  • Useful as catalysts
• What type of ions do transition elements typically have?

  They have ions with many different charges