Chemistry PreFinal

• Compounds are substance made up of two or more different chemical elements combined in a fixed ratio
• When elements come together, they react with each other and form chemical bonds that are difficult to break
• Covalent Compounds are formed from two non or more non-metal elements
• Ionic Compounds is formed from two ions, a combination of metals and non metals
• Diatomic Molecules where some elements exist in nature as molecules
• Chemical Formulas are used to express the composition of molecules and ionic compounds in terms of chemical symbols
• Molecular Formulas give the exact number of each element present in the smallest unit of a substance. It gives the kind and number of atoms of each element present in the molecular compound
• Structural Formulas is a graphic representation of the molecular structure. It shows how the atoms are possibly arranged in the real 3-D space. It provide a more complete geometric representation of the molecular structure
• Ball and Stick Model are 3-D models where atoms are represented by sphere of different colors and bonds are represented by sticks between the spheres.
• In the ball and stick model particular atoms are associated with different colors, black is usually used to represent carbon and white to represent hydrogen
• Space Filling Model shows how much space an atom or molecule occupies. It is more accurate in depicting the sizes of atoms. However, they are time consuming to construct
• Perspective Diagram, in order to represent such configurations on a two dimensional surface, we often use perspective drawings in which the direction of a bond is specified by the line connecting the bonded atoms
• Empirical Formula are formulas that show which element are present and in what ratio they exist in the substance. The ones you get when analyzing compounds
• In the Empirical Formula, it is the simplest whole number ratio of elements
• In the Molecular Formula the actual whole number ratio multiple of empirical
• Ionic compounds have charges that are neutral even though they are made up of ions.
• Monatomic Ions contain only 1 atom which can be either be negatively or positively charged
• Polyatomic Ions contain 2 or more atoms that are can either be positively or negatively charged. The change carried by the polyatomic ion is the sum of the charges of all atoms in the ion
• Acids are a molecular compound that contains one or more hydrogen atoms and produces hydrogen ions when dissolved in water
• Molecular - which means that in their pure state they are individual molecules and do not adopt the extended three-dimensional structure of ionic compounds
• A binary acid is an acid that consists of hydrogen and one other element
• The most common binary acids contain a halogen
• An Oxyacid is an acid that consists of hydrogen, oxygen, and a third element. The third elements is usually a nonmetal
• Acids are electrically charged
• Mole is the SI unit for amount of substance
• The number 6.02 x10^23 is called the Avogadro's number
• An Italian physicist and lawyer Amadeo Avogadro di Quaregna
• Representative particle is the species present in a particular substance
• Molar mass is the mass of one mole of a pure substance
• Molar mass is expressed in grams(g)
• Molecular mass is expressed in amu