Naming Compounds
- The first element in the compound retains its original name.
- The second element receives the suffix "-ide".
- Carbon becomes carbide.
- Oxygen becomes oxide.
- Phosphorus becomes phosphide.
- Prefixes are added to indicate the quantity of each element.
- One: Mono
- Two: Di
- Three: Tri
- Four: Tetra
- Five: Penta
- Six: Hexa
- Seven: Hepta
- Eight: Octa
- Nine: Nona
- Ten: Deca
- The prefix "mono" is omitted for the first element.
Examples:
- Carbon Dioxide (CO_2)
- Carbon: No prefix, implying one carbon atom.
- Oxygen: "Di" prefix indicates two oxygen atoms, named oxide.
- Carbon Monoxide (CO)
- Carbon: One carbon atom, no prefix.
- Oxygen: One oxygen atom, named monoxide.
- Dihydrogen Monoxide (H_2O) (Water)
- Hydrogen: "Di" prefix indicates two hydrogen atoms.
- Oxygen: "Mono" prefix indicates one oxygen atom, named monoxide.
- Diphosphorus Pentoxide (P2O5)
- Phosphorus: "Di" prefix indicates two phosphorus atoms.
- Oxygen: "Penta" prefix indicates five oxygen atoms, named oxide.
Acids
- Acids involve a relationship between hydrogen and a nonmetal anion.
- Acids must contain hydrogen.
Binary Acids
- Composed of hydrogen and a single element.
- Examples: HCl, HBr, H2S, H3P.
- Naming Convention:
- Start with "hydro-".
- Add the element's root name.
- End with "-ic acid".
- The "hydro-" prefix indicates the element stands alone, bonded to hydrogen only.
- HCl: Hydrochloric acid (chlor- from chlorine).
- HBr: Hydrobromic acid (brom- from bromine).
- H_2S: Hydrosulfuric acid (sulf- from sulfur).
Oxoacids
- These acids contain oxygen. They are derived from polyatomic ions.
- Important Anions to Remember: Sulfate (SO4^{2-}, Carbonate (CO3^{2-}, Phosphate (PO4^{3-}, Nitrate (NO3^{-}$)
- "-ate" Suffix Rule: When the anion name ends in "-ate", replace it with "-ic acid".
- Sulfate (SO4^{2-}) becomes sulfuric acid (H2SO_4).
- Carbonate (CO3^{2-}) becomes carbonic acid (H2CO_3).
- Phosphate (PO4^{3-}) becomes phosphoric acid (H3PO_4).
- Nitrate (NO3^{-}$) becomes nitric acid (HNO3).
- If the compound contains oxygen, there is no "hydro" prefix.
Naming acids - Examples
- H2SO4: Sulfuric acid (sulfate ion).
- H2CO3: Carbonic acid (carbonate ion).
- HBr: Hydrobromic acid (binary acid).
- "Hydro" prefix means hydrogen and the element alone.
Chemical Composition - Chapter 6
The Mole
- A mole is a unit of measurement.
- 1 mole = 6.02 \times 10^{23} (Avogadro's number).
- Avogadro's Number: 6.02 \times 10^{23}. It's the number of atoms, molecules, or particles in one mole of a substance.
- 1 mole of carbon-12 contains 6.02 \times 10^{23} atoms and weighs 12 grams.
Molar Mass
- The mass of one mole of a substance, usually expressed in grams per mole (g/mol).
- Molar Mass Equation: \text{Molar Mass} = \sum \text{Atomic Weights}
- To find molar mass, sum the atomic weights of each element in the chemical formula.
- The atomic weight is the number with a decimal found on the periodic table.
Calculating Molar Mass - Example
- Water (H_2O)
- Hydrogen (H): 1.008 g/mol (x2 = 2.016 g/mol).
- Oxygen (O): 16.00 g/mol (x1 = 16.00 g/mol).
- Molar Mass of Water: 2.016 + 16.00 = 18.016 g/mol.
Calculating Molar Mass - Example
- Sodium Chloride (NaCl)
- Sodium (Na): 22.99 g/mol
- Chlorine (Cl): 35.45 g/mol
- Molar mass of NaCl: 22.99 + 35.45 = 58.44 g/mol.
Mole Conversions
- Moles can be expressed using:
- Avogadro's Number: 1 mole = 6.02 \times 10^{23} atoms/molecules/particles.
- Molar Mass: 1 mole = X grams (where X is the molar mass of the substance).
- These equalities can be written as fractions for dimensional analysis.
Dimensional Analysis Reminder
- Given number and unit → Conversion factors → Desired unit.
Mole Conversion - Example
- How many grams of lead (Pb) are in 2 moles of lead?
- Given: 2 moles of Pb.
- Molar mass of Pb: 207.2 g/mol (from the periodic table).
- Conversion: 2 \text{ mol Pb} \times \frac{207.2 \text{ g Pb}}{1 \text{ mol Pb}} = 414.4 \text{ g Pb}
Mole Conversion - Example
- How many moles of lead (Pb) are there in 3.4 grams of lead?
- Given:3.4 g of Pb
- Known: Molar Mass Pb = 207.2 g/mol
- 3.4 g Pb * \frac{1 mol Pb}{207.2 g Pb} = 0.016 \text{ mol Pb}
Two-Step Conversions
Grams can be converted to moles using molar mass, and moles can be converted to atoms/molecules using Avogadro's number, and vice versa.
Multi-Step Conversion - Example
- How many atoms are there in 3.4 grams of lead?
- 3.4g Pb → moles of Pb → Atoms PV
- Given 3.4 grams of lead, PV is 207.2g
3.4 g Pb * \frac{1 mol Pb}{207.2 g Pb} * \frac{6.02 \times 10^{23} atoms Pb}{1 mol Pb} = 9.9 \times 10^{21} atoms Pb