Gen Chem

• chemical formula 


  represents pure substances, either elements or compounds
• chemical formulas consist of symbols of the elements contained in the substance and subscript numbers
• what are the types of chemical formulas

  molecular formula

  empirical formula

  structural formula
• molecular formula


  this gives the composition of the molecule in terms of the actual number of atoms present
• structural formula


  shows the location of the atoms relative to one another in a molecule and the number of chemical bonds between the atoms
• empirical formula


  gives only the relative number of atoms of each type in a molecule
• standard types of formulas and models

  molecular formula

  structural formula

  ball and stick model

  space filling model
• molecular formula shows the exact number of atoms of each element
• empirical formula shows the simplest whole number ratio
• the formula of the elements is its chemical symbol
• a molecule is the smallest particle of a pure substance that has the composition and characteristics of the substance
• a molecule is an aggregate of two or more atoms (usually nonmetals) in a definite arrangement held together by chemical forces
• monoatomic molecules


  these are molecules consisting of only one atom
• diatomic molecules


  their chemical formula consists of the symbol of the element followed by a subscript of two
• polyatomic molecules


  contain more than two atoms in their molecules
• an ion is an atom, or group of atoms, that has a net positive or negative charge
• cation is an ion with a positive charge
• if a neutral atom loses one or more electrons, it becomes a cation
• anion is an ion with a negative charge
• if a neutral atom gains one or more electrons, it becomes an anion
• a monoatomic ion contains only one atom
• a polyatomic ion contains more than one atom
• compounds are substances formed from two or more elements chemically united in fixed proportions
• ionic compounds consist of a combination of cations and anions
• 3 types of ionic compounds

  binary ionic compounds

  transition metal ionic compounds

  ternary ionic compounds
• binary ionic compounds have -ide added to the element
• transition metal ionic compounds indicate charge on metal with roman numerals
• in the traditional method, the latin name of the metal uses -ous for lower charge and -ic for higher charge
• ternary ionic compounds are compounds with three(3) elements and usually involves polyatomic ions
• an acid can be defined as a substance that yields hydrogen ions when dissolved in water
• an oxoacid is an acid that contains hydrogen, oxygen, and another element
• a base can be defined as a substance that yields hydroxide ions when dissolved in water
• hydrates are compounds that have a specific number of water molecules attached to them
• valence electron is a single electron or one of two or more electrons in the outer shell of an atom that is responsible for the chemical properties of the atom
• oxidation number is a number assigned to an element in chemical combination which represents the number of electrons lost or gained by an atom of that element in the compound
• 2 methods of ionic compound

  stock method

  traditional method
• stock method uses roman numerals
• traditional method uses -ic and -ous
• molecular compounds are made up of two nonmetals
• binary acids are composed of hydrogen and another element, usually a nonmetal