C1 key concepts

• Approximately how big is a molecule?

  200 pm (2 x 10^-10 m)
• Approximately how big is an atom?

  100 pm (1 x 10^-10 m)
• Mendeleev organised the elements into the Periodic Table using properties of elements and compounds
• Dalton-tiny hard spheres-All substances are made of atoms. Atoms are small particles that cannot be created, divided, or destroyed.
• Thompson-plum pudding model-negative electrons are scattered throughout soft blobs of positively charged material.
• Rutherford-alpha particles shot at gold foil,discovered dense region in the middle (nuclues),electrons travel around nucleus
• relative atomic mass:​(mass of isotope-A x % of isotope-A) + (mass of isotope-B x % of isotope-B) ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​/ 100
• metals-react to form + ions,loose elements in order to form these ions,forming stable structure like noble gas
• non-metals- form - ions,gain electrons to be stable like noble gas
• ionic bonds

  transfer of electrons to produce a full outer shell between METAL and NON METAL

  form cations and anions

  FORCE OF ATTRACTION BETWEEN OPP CHARGED IONS =ELECTROSTATIC FORCE
• ionic compounds

  High melting and boiling points

  Conduct electricity-but only as water/liquid=ions are free to move (delocalised)
• -ide= non metal forms a negative ion
• -ate=when a compound contains oxygen asw another element,NON METAL FORMS THIS ONLY
• lattice structure

  a giant structure of ions

  held by strong electrostatic forces,which act in all directions

  regular arrangement of ions
• covalent bonds

  sharing of electrons,with NON METALS

  INTERMOLECULAR FORCES

  leads to formation of molecules=SIMPLE/GIANT COVALENTS
• Simple molecular substances COVALENT RMBR!

  low boiling and melting points=weak intermolecular forces

  dont conduct electricity=no overall charge -but when broken down in water they do

  Many are insoluble in water, but some are soluble=can form intermolecular forces with water stronger than water molecules
• Giant covalent structures

  strong intermolecular forces

  high melting and boiling points

  some conduct electricity

  insoluable in water
• metallic bonding

  giant structure of atoms arranged in regular patterns

  delocalised electrons = contains heat and electricity=gives strong metallic bonds

  high melting and boiling points

  STRENGTH

  malleable=atom layers can slide over eachother

  Electrostatic forces

  coductivity=ability for electrons to move

  INsoluable
• Diamond

  carbon joined to 4 other carbon atoms

  no free electrons=cannot conduct

  rigid strucute w strong covalent bonds =cutting tools/diamond tipped drils

  high melting points
• graphite

  bonded to 3 other carbons=forms layers w hexagonal rings

  layers can slide=weak intermolecular forces=soft & slippery

  one delocalised electron = conducts electricity

  pencils/lubricants/electrodes
• Graphene

  -single layer of graphite

  high melting points

  strong =regular arrangement

  useful in electronics and composites
• Fullerenes

  molecular form of carbon with hollow shapes eg nano tubes and buckyballs

  based on hexagonal rings of carbon atoms, but they may also contain rings with five or seven carbon atoms

  first fullerene to be discovered was Buckminsterfullerene (C60), which has a spherical shape
• Carbon nanotubes

  cylindrical fullerenes,high length to diameter ratios

  used in nanotech,electronics and tennis racket frames

  high tensile strength(tension)

  conduct electricity
• Buckyballs

  spheres of carbon atoms

  weak intermolecular forces

  little energy=low boiling points and slippery
• polymers

  large molecules with repeat units

  strong covalent bonds

  solids at room temp
• allotropes

  two subsatnces made from same elemetns,same physical state but different structures rg diamond and grpahite
• What is the definition of one mole of particles of a substance?

  The Avogadro constant number of particles of that substance

  or

  a mass of ‘relative particle mass’
• How do you calculate the number of moles of a substance? (2 equations)

  Number of moles = mass (g) / relative formula mass

  Number of moles = number of particles / Avogadro’s constant
• What is the formula of a hydroxide ion?

  OH-

  What is the formula of a nitrate ion?

  NO3-

  What is the formula of a carbonate ion?

  CO32-

  What is the formula of a sulfate ion?

  SO42-
• simple molecular substances have low boiling points because there are weak intermolecular forces between the molecules which don’t require much energy to break.
• ionic compounds have High boiling points because there are strong electrostatic forces of attraction between the ions which require lots of energy to break.
• What are the stages for calculating the empirical formula of a compound?

  1. Write down the masses or percentages given in the question
  2. Divide by the relevant relative atomic mass
  3. Divide by the smallest number
  4. Write down the simplest whole number ratio
• What is the unit for concentration of a solution?

  g dm-3
• How do you convert from cm3 into dm3?

  Divide by 1000
• Where can you find the relative atomic mass of an element?

  It’s the larger / top number on the Periodic Table.
• ball-stick -> doesnt show which atoms the e- in the bonds come from
• dot and cross->


  doesnt show relative size of atoms or their arrangement in space
• displayed formula-> doesnt show 3d structure or sizes of atoms
• 3d model->only shows outer layer