Presentation on theme: "Compounds and Nomenclature. Bonding & Stability Atoms want to be stable. The Octet Rule states that a chemically stable atom contains 8 valence electrons."— Presentation transcript:
Types of Compounds 1. Ionic Compounds: -involve the transfer of electron(s) between 2 oppositely charged ions (cation and anion) -metal and a nonmetal or a combination involving a complex ion -forms an ionic bond -exists as an ionic crystal lattice (not individual molecules) -known as a formula unit (eg. A formula unit of salt, not a molecule)
Formula Unit a chemical formula showing the simplest whole number ratio of cations to anions in an ionic compound. Eg. NaCl – sodium chloride
Types of Compounds (continued) 2. Molecular compounds: -involve the sharing of electrons between nonmetals -forms a covalent bond - exists as individual molecules - Eg. Carbon dioxide CO 2 water H 2 O
Properties of Ionic and Molecular Compounds 1.State at room temperature: -all ionic compounds are solids -molecular compounds may be a solid, liquid or a gas 2.Conductivity of solution: -ionic compounds conduct electricity (electrolytes) -molecular compounds do not conduct electricity (non-electrolytes)
3.Solubility in water: -ionic compounds are soluble, to varying degrees (some better than others) and form colored or colorless solutions. -molecular compounds may or may not be soluble (colorless solutions if they form).
Nomenclature Chemical nomenclature is the systematic naming of chemical compounds. Science 1206 examines the naming of ionic compounds, molecular compounds and acids. Compounds can be divided into two basic categories, those which are true binary compounds (contain only two types of elements), and those which contain more than two different types of elements.
Ionic compounds Identify the type of ions: A. Monoatomic or simple ions B. Polyatomic or complex ions C.Multivalent ions D.Hydrates
Rules for Naming ionic compounds: A. Monoatomic or simple ions Single atoms that have lost or gained one or more electrons Form binary ionic compounds (2 simple ions) Consist of cations and anions Eg. Sodium + chlorine Na + Cl -
Cations are written first, anions are second (name changes to “-ide” for the anion) The total charge must be zero Do not write charges in your final answer
Naming Ionic Compounds Cation is named first Anion is named second Ending of anion is changed to “ide” Practice: NaClBaCl 2 Al 2 O 3
B. Multivalent ions -certain transition metals can form more than one type of ion, each with a different charge. - eg. Cu 2+ - copper (II) Cu + - copper (I)
Multivalent ions (continued) The transition metals have various electron configurations that will make them stable Use a roman numeral after the cation to specify its charge (Stock naming system). Eg. Iron (ii) oxideFeO Iron (iii) oxideFe 2 O 3
Stock vs. Classical FormulaStock NameClassical Name Cu + copper(I) ionCuprous ion Cu 2+ copper(II) ionCupric ion Fe 2+ iron(II) ionFerrous ion Fe 3+ iron(III) ionFerric ion
-the one written on top is the more common ion - eg. Fe 3+ - iron (III) Fe 2+ - iron (II)
C. Polyatomic/Complex Ions Polyatomic ion: atoms of 2 or more elements covalently bonded together with an overall charge eg. Nitrate NO 3 - AmmoniumNH 4 + Complex ions are groups of atoms that are made stable by sharing electrons and which then become even more stable by gaining (usually) or losing electrons.
The total positive charge in the formula must be equal to the total negative charge. Rules: Name the cation, then name the anion Don’t change the ending of a polyatomic ion! Balance the charges If you need more than 1 complex ions, use brackets for that group
Practice NaNO 3 Al 2 (SO 4 ) 3 Mg(OH) 2 NaCH 3 COO
D. Hydrates Ionic compounds that contain water in their structure eg. CuSO 4 H 2 O
Hydrate - Rules Name the ionic part of the formula first Name the water part second using a prefix system for the number of water molecules Add prefix to “hydrate” Prefixes: 1. mono 2. di 3. tri 4. tetra 5. penta 6. hexa 7. hepta 8. octa 9. nona 10. deca
Example: CuSO 4 5H 2 O Copper (II) sulfate pentahydrate
Binary molecular compounds form between 2 non-metals Covalent bonds: shared electrons Molecular formula: shows number and kind of atoms in a molecule
Naming Use prefixes to specify number of atoms of each element in the molecule Second element ends with “-ide” No charges used in formula The prefix “mono-” should not be used on the first element 1. mono 2. di 3. tri 4. tetra 5. penta 6. hexa 7. hepta 8. octa 9. nona 10. deca
Practice Name the following: NO CO 2 N 4 O 9 N 6 O Write formulas for the following: Boron trifluoride Sulfur hexafluoride Nitrogen monoxide Phosphorous pentachloride
ACIDS HClHydrochloric Acid H 2 SO 4 Sulfuric Acid HNO 3 Nitric Acid HC 2 H 3 O 2 Acetic Acid H 3 PO 4 Phosphoric Acid H 2 CO 3 Carbonic Acid
Acids have 2 criteria: 1.They must contain hydrogen (H + ) 2.They must be dissolved in water (aqueous); the formula will always contain the subscript aq.
Naming Acids Hydrogen is always the positive ion for an acid Ending Acid Name Example 1. -ide begins with hydro,HCl ends with -ic and acid 2. –ite ends with –ous and acid H 2 SO 3 3. –ate ends with –ic and acid H 2 SO 4