Presentation on theme: "Chemical Naming & Formula Writing How do you do this???"— Presentation transcript:
Chemical Naming & Formula Writing How do you do this???
What are Ionic Compounds? Ionic compounds consist of a cation (+ ion) and an anion (- ion) Monotomic cations can be found to the left of the staircase Monotomic anions can be found to the right of the staircase Ex: NaCl, CaBr 2, K 3 PO 4, NH 4 Cl
How are Ionic Compounds Bonded? Ionic compounds are formed when electrons are transferred between the cation and anion The cation will lose electron(s) to become stable and look like a noble gas The anion will gain electron(s) to become stable and look like a noble gas
How is NaCl Formed? Na Cl Na has 1 valence electron and Cl has 7 valence electrons. Na will transfer its 1 valence electron to Cl so that they can both become stable and look like noble gases. Na +1 now looks like Ne from the outer shell and Cl -1 now looks like Ar.
What Does an Ionic Formula Represent? An ionic formula represents the lowest whole number ratio of atoms in a compound This ratio is referred to an a formula unit Na+ (green) ions will ionically bond with Cl- (purple) ions in a repeating pattern toform what is called a crystal lattice.A formula unit is the lowest whole numberratio of the Na to Cl atoms which would be 1:1 NaCl. Na+ (green) ions will ionically bond with Cl- (purple) ions in a repeating pattern toform what is called a crystal lattice.A formula unit is the lowest whole numberratio of the Na to Cl atoms which would be 1:1 NaCl.
Unique Properties of Ionic Compounds? Solids at room temperature Relatively high melting points (>300°C) High solubility in water No conductivity as a solid but as an aqueous solution or molten, they are conductive You must have ions present in order to conduct electric current
What are Molecular Compounds? Molecular compounds consist of 2 nonmetals located to the right of the staircase 2 types: polar and nonpolar covalent Polar covalent compounds usually are made up of 2 or more different nonmetals Ex: H 2 O, NH 3, CO Nonpolar covalent compounds usually are made up of 2 of the same nonmetals Ex: Br 2, Cl 2, O 2
How are Molecular Compounds Formed? For polar covalent compounds, electrons are unequally shared between the nonmetals to achieve noble gas stability The higher electronegative element will pull the electron(s) its sharing closer to it than the less electronegative element For nonpolar covalent compounds, electrons are equally shared between the nonmetals to achieve noble gas stability
Nonpolar covalent equal sharing of an electron between 2 F atoms to become more stable and look like Ne F2F2 H2OH2O Polar covalent unequal sharing of an electron between each of the 2 H atoms and the O atom allows H to look like He and O to look like Ne. The electrons are pulled closer to because it is the more electronegative element
What Does a Molecular Formula Represent? A molecular formula represents the actual number of atoms in a compound There are 2 H and 1 O atoms in 1 water molecule There are 3 H and 1 N atoms in 1 ammonia molecule
Unique Properties of Polar Covalent Compounds? Usually liquids or gases at room temperature Melting point is <300°C (less than ionic) Solubility in water varies Not conductive
Unique Properties of Nonpolar Covalent Compounds? Gases at room temperature (exceptions include I 2 solid and Br 2 liquid ) Very low melting point (less than polar covalent) No solubility in water Not conductive
What are Metallic Compounds? Metallic compounds consist at least one metal Ex: Cu, Pt, Sn, Pb, Ag Metallic compounds made up of more than 1 metal are called alloys Ex: brass (70% Cu & 30% Zn), stainless steel, pewter, 14K-24K Au
How are Metallic Compounds Formed? Metallic compounds are bonded by a sea of electrons that hold the metal cations together The delocalized electrons do not belong to any single cation. They swim in the sea, holding the cations together
What Does a Metallic Compound Represent? Like an ionic formula, metallic formulas also represent the lowest whole number ratio of atoms in a compound This ratio is referred to an a formula unit
Unique Properties of Metallic Compounds? Solids at room temperature (exception Hg liquid ) Very high melting points (higher than ionic) No solubility in water Conductive because of the mobile ions swimming in the sea of delocalized electrons