Chemical Names and Formulas 6.1 Introduction to Chemical Bonding 6.2 Representing Chemical Compounds 6.3 Ionic Charges 6.4 Ionic Compounds 6.5 Molecular Compounds and Acids 6.6 Naming and Formula Writing

6.1 Objectives Distinguish between ionic and molecular compounds Define cation and anion, relate them to metal and non- metal metal/cation nonMetal/anion

6.1 Vocabulary Molecule Molecular compound Ions Cations Anions Ionic compounds

Introduction to Chemical Bonding Molecules and Molecular Compounds Tend to have low boiling and melting points May be gases or liquids at room temperature (RT) Are composed of non-metals, CO2 Ions and Ionic Compounds, (+) and (-) Have balanced charges, 2(+) must have 2(-) Have high boiling and melting points, (solid at RT) Are composed of metals and non-metals (combined)

Ions: Symbols and Names Cations: these are metals that lose electrons When you lose a (-) you become more positive If Potassium (K) loses 1 electron it becomes K+1 Example: (19+ and 19–) changes to (19+ and 18-) Anions: these are nonMetals that gain electrons When you gain a (-) you become more negative If Bromine (Br) gains one electron it becomes Br-1 Example: (35+ and 35-) changes to (35+ and 36-) Anions change their suffix to –ide, (Bromine to Bromide)

Characteristics of Compounds Molecular Compound Ionic Compound Representative Unit Molecule Formula Unit Type of Elements nonMetals Metal and nonMetal Physical State Solid, liquid , or Gas Solid Melting Point Low, (below 300 C) High, (above 300C)

Questions What is the symbol and name for an Oxygen atom that has gained two electrons? O2- and Oxide What is the symbol and name for an Iron atom that has lost two electrons? Fe2+ and Iron (II)

Definitions A Molecule is the smallest electrically neutral unit of a substance A Molecular compound are combinations of atoms Ions are charged atoms or molecules Cations are positively charged (+) Anions are negatively charged (-) Ionic compounds combine the (+) and (-)

6.2 Objectives Distinguish among chemical formulas, molecular formulas, and formula units Use experimental data to show that a compound obeys the law of definite proportions

Vocabulary Chemical formula Molecular formula Formula unit Law of Definite Proportions Law of Multiple Proportions

Formula Unit is a crystal

HONClBrIF Diatomic Molecules, (exist as two bonded atoms) (H) Hydrogen as H2 (O) Oxygen as O2 (N) Nitrogen as N2 (Cl) Chlorine as Cl2 (Br) Bromine as Br2 (I) Iodine as I2 (F) Fluorine as F2

Counting Atoms and Assigning Mass When elements react to form compounds, they react in defined, whole-number ratios. The experiments that Dalton and others performed showed that reactions are not random events; they proceed according to precise and well-defined formulas.

Water, for example, is always made up of two parts hydrogen and one part oxygen. The chemical formula of a compound is written by listing the symbols of the elements together, without any spaces between them. If a molecule contains more than one atom of an element, a number is subscripted after the symbol to show the number of atoms of that element in the molecule. Thus the formula for water is H2O, never HO or H2O2.

Questions How are the images different? In every sample of Carbon Monoxide the mass ratio is 3:4 for the mass of Carbon : Oxygen. In sample 1: Carbon is 9 grams and Oxygen is ____ In sample 2: Carbon is _____and Oxygen is 8 grams

Definitions A Chemical formula shows the kind and number of atoms in a representative unit A Molecular formula shows the kind and number of atoms in a molecule A Formula unit is the lowest whole number ratio in a compound, when ions come together to form a crystal Law of Definite Proportions: the masses of the elements in a compound always conform to a ratio Law of Multiple Proportions: different compounds may have different ratios of the same elements

6.3 Objectives Use the Periodic Table to determine the charge of an ion Define a polyatomic ion Name the most common examples of polyatomic ions

Vocabulary Monoatomic ions Polyatomic ions

The Mono-Atomic Ions See the table on page 143 for the Representative Elements See the table on page 144 for some Transition Metal Elements

Some Transition Metal Ions Complexes may be quite colorful The paint industry uses transition metal ions to provide color

Poly-Atomic Ions Ammonium ion is positive (+) Nitrate ion is negative (-) In each case there are multiple atoms acting as a tightly bound unit The table on page 147 provides a good list

Questions What is the charge on a Potassium atom that has changed to an ion? What is the charge of a Bromine atom that has changed to an ion? Using page 147, what is the charge of Sulfite? What is the charge of Iron (III)? How would you write an ion of Cobalt (II)? What is the name of Sn+4 ?

Definitions Monoatomic ions are ions consisting of only one atom Cation: Li+1 Anion: Br-1 Polyatomic ions are tightly bound groups of atoms that behave as a unit and carry a charge Cation: NH4+1 Anion: Cr2O7-2

6.4 Objectives Apply the rules for naming and writing formulas for binary compounds Apply the rules for naming and writing the formulas for ternary ionic compounds

Vocabulary Binary compounds Ternary compounds

How to write a chemical formula Start by identifying the types of atoms Hydrogen and Oxygen Count the atoms of each type Two H and One O leads to the formula H2O

Naming a binary ionic compound Determine the positive ion, in this case Sodium+ Determine the negative ion, in this case Chlorine- Determine the charges (+) and (-), both are 1 The positive (cation) is first, then the anion Sodium Chloride is NaCl and has no charge

Naming a ternary ionic compound Notice the green ball, (Mg+2), and the ball that is red/white, (OH-), the ratio is 1:2 or Mg(OH)2 Magnesium Hydroxide

Definitions Binary compounds are composed of two elements NaCl Ternary compounds are composed of three different elements CaCO3

6.5 Objectives Apply the rules for naming and writing formulas for binary molecular compounds Name and write formulas for common acids

Binary molecular compounds Prefixes for naming binary molecular: mono- 1 di- 2 tri- 3 tetra- 4 penta- 5 hexa- 6 hepta- 7 octa-8 nona- 9 deca- 10 - diNitrogen tetraHydride, (N2H4)

Naming common acids (aq) means it is in water Acids break apart in water Six acids are commonly used, (see the chart at left) There are rules for naming acids, (hydro- and –ic acids)

6.6 Objectives Use the flowchart in Fig. 6.21 to write the name of a compound when given its chemical formula Use the flowchart in Fig. 6.23 to write a chemical formula of a compound when given its name