Topic 3 Vocab

• Measurement uncertainty 


  estimate of how far the experimental value might be from the true value
• significant figures 


  are those digits in a number that are known with certainty plus its first digit that is uncertain
• mole 


  defined as 6.022 x 10^23 elementary entities of a substance. one mole of any substance contains 6.022 x 10^23 particles of that substance
• Avogadro's number 


  6.022 × 10^23
• molar mass 


  obtained directly from periodic table and is the relative formula mass or relative molecular mass of the compound. Expressed in grams per mole. (gmol-1)
• percentage composition 


  percentage by mass of each element present in a compound
• concentration 


  amount of solute dissolved in a given amount of solution
• empirical formula 


  simplest ratio of elements present in a compound
• molecular formula 


  exact formula of a molecule that gives the accurate number of each atom present
• chemical bond 


  electrostatic force of attraction between opposite charges in matter
• metallic bond 


  strong electrostatic attraction between cations and delocalised electrons
• delocalised 


  electrons able to move around
• malleable 


  substance that is able to be hammered or bent into shape without breaking or cracking
• ductile 


  able to be drawn out into a thin wire
• brittle 


  fractures when subjected to stress but has a tendency to deform before rupture
• alloy 


  homogeneous mixture of two or more elements, where at least one element is a metal
• ionic bond 


  strong electrostatic bond between oppositely charged ions
• covalent bond


  electrostatic attraction between a shared pair of electrons and two adjacent nuclei
• molecule 


  group of atoms joined by covalent bonds
• intermolecular force


  force of attraction between molecules are weak forces
• Lewis structure 


  way of representing the number and arrangement of valence electrons in atoms, molecules and ions
• bonding pair 


  two electron shared between atoms creating a bond
• non-bonding pair 


  pair of valence electrons not involved in any covalent bonding
• allotrope 


  different structural forms of the same element