C - Definitions List

• Valency


  Capacity an atom has for bonding
• Isotopes


  Atoms of the same element with different neutrons
• Relative Atomic Mass (Ar)


  Weighted mean mass relative to 12C
• Atomic Orbital


  Region with high electron probability
• Covalent Bond


  Strong attraction between shared electrons
• Dative Covalent Bond


  Attraction with one atom donating electrons
• Electronegativity


  Atom's ability to attract electrons in bond
• Bond Polarity


  Charge unevenness due to electronegativity difference
• Ionic Bond


  Attraction between oppositely charged ions
• Metallic Bond


  Attraction in lattice with delocalized electrons
• Periodicity


  Repeating trends in properties across periods
• Exothermic Reaction


  Release of energy forming bonds
• Endothermic Reaction


  Absorption of energy breaking bonds
• Activation Energy


  Minimum energy for reaction initiation
• Reversible Reaction


  Products can reform reactants
• Dynamic Equilibrium


  Constant reactant/product concentrations
• Structural Isomers


  Same formula, different structure
• Stereoisomers


  Same formula, different spatial arrangement
• Optical Isomerism


  Non-superimposable mirror image isomers
• Chiral Centre


  Carbon atom bonded to 4 different groups
• Free Radical


  Molecule with unpaired electron
• Homolytic Bond Fission


  Bond electron distribution to form radicals
• Heterolytic Bond Fission


  Electron distribution forming ions
• σ Bond


  Orbital overlap on bond axis
• π Bond

  P-orbitals overlap above and below bond axis
• Valency


  Capacity an atom has for bonding, the number of electrons able to take part in bonds
• Isotopes


  Atoms of the same element (same atomic number) but with different number of neutrons (different mass number)
• Relative Atomic Mass (Ar)


  Weighted mean mass of an atom of an element relative to a 1/12th the mass of an atom of 12C
• Atomic Orbital


  Region of space with a high probability of finding an electron. Four types: s, p, d, f
• Covalent Bond


  Strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
• Dative Covalent Bond


  Strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms, but the pair of electrons are donated by one of the atoms only
• Electronegativity


  Ability of an atom to attract the bonding pair of electrons in a covalent bond
• Bond Polarity


  Uneven distribution of charge due to a large difference in electronegativities of atoms in a covalent bond
• Ionic Bond


  Electrostatic attraction between oppositely charged ions in a lattice
• Metallic Bond


  Electrostatic attraction between a lattice of positively charged ions and a sea of delocalized electrons forming a giant metallic structure
• Periodicity


  Repeated trends found across periods in physical and chemical properties
• Exothermic Reaction


  Releases thermal energy to surroundings, more energy released forming bonds than put in to breaking bonds
• Endothermic Reaction


  Absorbs thermal energy from surroundings, more energy put in to breaking bonds than released forming bonds
• Activation Energy


  Minimum amount of energy that reactants require for a reaction to proceed
• Reversible Reaction


  Products can react to reform the original reactants, represented using ⇌