Science T1 Atomic structure.

• What particles are contained in the nucleus of an atom?


  Protons and neutrons
• What is the charge of electron shells?


  They are negatively charged
• What is the relative mass and charge of a proton?


  Relative mass is 1 and charge is +1
• What is the relative mass and charge of a neutron?


  Relative mass is 1 and charge is 0
• What is the relative mass and charge of an electron?


  Relative mass is very small and charge is -1
• Why do atoms have no overall charge?


  They have the same number of protons as electrons
• What is an ion?


  An ion is a charged particle with unequal numbers of protons and electrons
• What is the equation to calculate relative atomic mass?


  relative atomic mass (A) =
• What are the characteristics of mixtures?


  • No chemical bonds
  • Easy to separate
  • Examples: air, salt water
• What is chromatography used for?


  To separate out mixtures
• What is filtration used for?


  To separate solids from liquids
• What is required for balancing symbol equations?

  • Same number of atoms on both sides
  • Example: CH₄ + 2O₂ → 2H₂O + CO₂
• What is an element made of?

  Atoms with the same atomic number
• What is the symbol for nitrogen?


  N
• What is the symbol for fluorine?


  F
• What is the symbol for zinc?

  Zn
• What is the symbol for calcium?


  Ca
• What is an isotope?


  An isotope has the same number of protons but a different number of neutrons
• How many protons, electrons, and neutrons are in the isotope H-1?


  1 proton, 1 electron, 0 neutrons
• How many protons, electrons, and neutrons are in the isotope H-2?


  1 proton, 1 electron, 1 neutron
• How many protons, electrons, and neutrons are in the isotope H-3?


  1 proton, 1 electron, 2 neutrons
• What is a compound?


  • Two or more elements chemically joined
  • Examples: carbon dioxide, magnesium oxide
  • Difficult to separate
• How can a chemical reaction be represented?


  • Word equation: e.g. magnesium + oxygen → magnesium oxide
  • Symbol equation: e.g. 2Mg + O₂ → 2MgO
• What is the purpose of balancing chemical equations?


  To ensure the same number of atoms on each side
• What are the methods to separate a soluble salt from a solution?


  1. Evaporation - quick method
  2. Crystallisation - slower method
• What are the steps to separate salt from rock salt?


  1. Grind the mixture of rock salt
  2. Add water and stir
  3. Filter the mixture
  4. Evaporate the water to leave crystals
• What is simple distillation used for?


  To separate a liquid from a solution
• What is fractional distillation used for?


  • To separate a mixture of liquids
  • Example: separating crude oil into fractions
• Who first described atoms as solid spheres?


  John Dalton
• What model did JJ Thomson propose?


  The plum pudding model
• What did Rutherford's scattering experiment reveal?


  Most of the atom is concentrated at the nucleus
• What did Niels Bohr discover about electrons?


  Electrons are in shells orbiting the nucleus
• Who discovered neutrons in the nucleus?


  James Chadwick
• What is the electronic structure of atoms?


  • Electrons in shells
  • Maximum of 2 in the inner shell
  • 8 in the 2nd and 3rd shells
  • Fill inner shell first
• What are the properties of halogens?


  • Non-metals: fluorine, chlorine, bromine, iodine
  • Less reactive down the group
  • Higher melting and boiling points down the group
• What are the properties of noble gases?


  • Group 0 elements: helium, neon, argon
  • Un-reactive due to full outer shells
  • Colourless gases at room temperature
  • Boiling points increase down the group
• How was the periodic table developed?


  • Early 1800s: arranged by atomic mass
  • Incomplete due to undiscovered elements
  • Mendeleev left gaps for undiscovered elements
• What is the modern periodic table based on?

  • Order of atomic mass/proton number
  • Metals on the left, non-metals on the right
  • Group number indicates outer shell electrons
  • Periods show full shells of electrons
• What are the properties of alkali metals?


  • Soft, very reactive metals
  • One electron in outer shell
  • Low density
  • More reactive down the group
• What do alkali metals produce when they react with water?


  Hydrogen gas