Course:CHEM121/Some Basic Concepts

From UBC Wiki
Jump to: navigation, search
  • Extensive Properties: properties of matter that depend on the quantity of the matter observed (volume, mass, heat).
  • Intensive Properties: properties of matter that are independent of the amount of matter observed (density, temperature).
  • Homogeneous mixtures: uniform throughout and include such things as solutions
  • Hetrogeneous mixtures: not uniform; components of the mixture vary in concentration throughout the mixture.
  • Qualitative Properties: subjective properties (colour, Odour, etc.)
  • Quantitative Properties: Objective and empirical properties (weight, volume, etc.)
  • Precision: the degree of reproducibility of a measured quantity.
  • Accuracy: how close a measured value is to the actual value.
  • Isotopes: elements with the same number of protons but a different number of neutrons and a different atomic mass.
  • Allotropes: different structural forms of the same element (O2, O3)
  • Atomic number: or (Z) is the number of protons in the nucleus of an atom. Atomic number is not the number of electrons in an atom, however, in an electronically neutral atom the number of electrons and protons happens to be the same.
  • Atomic mass: = (fractional abundance of isotope 1)(mass of isotope 1)+ (fractional abundance of isotope 2)(mass of isotope 2) + . . . + (fractional abundance of isotope n)(mass of isotope n)
  • Avogadro Constant: number of elementary entities in a mole, 6.02x10^23 mol^-1
  • Theoretical Yield: the calculated quantity of product that one expects from given quantities of reactants.
  • Strong Acid: molecular compounds that are almost completely ionized in water.
  • Strong Base: one that is completely ionized in an aqueous solution.
  • Weak Acid: one that is incompletely ionized in aqueous solution.
  • Oxidation:loss of electrons by a chemical species [Oil--> Oxidation Is Losing]
  • Reduction:gain of electrons by a chemical species [Rig--> Reduction Is Gaining]
  • Oxidizing Agent: oxidizes another compound; itself is reduced in the process.
  • Reducing Agent: reduces another compound; itself is oxidized in the process.
  • Bond pair: pair of electrons being shared between two atoms, represented by a line
  • lone pair: pair of electron not invovled in sharing between two atoms; belong to the element itslef

Lewis Diagram

only shows the valence electrons: use group/family number to figure out how many electrons in the valence shell

covalent compound

-usaully between a non-metal and non-metal -both atoms found on Left side of periodic table -both have negative ion charge--> both want to take electrons -therefore, share electrons between them, inorder for all atoms involved to have full valence elctrons (1 outer electrons) "compromising realtionship"

ionic compound

-always between between metal and nonmetal -first atom positive ion, last atom negative ion first atom found on Right side of periodic table, last atom found on left side of periodic table -transfer of electrons occur ("give-take realationship") -until valence shell of all atoms involved are stable (has 8 electrons)

Back to ChemHelp Back to Chem121