chem chapter 3 2/27/25

Ionic Compounds vs. Molecular Compounds

• Ionic Compounds: Formed from metal and nonmetal ions, characterized by the transfer of electrons.

• Molecular Compounds: Composed of nonmetals, involve covalent bonds where electrons are shared.

Naming Molecular Compounds

• Naming Convention:

  • Name the first element (e.g. Nitrogen).

  • Name the second element and change the suffix (e.g. Iodine to Iodide).

  • Use prefixes to indicate the number of atoms (e.g., Tri- for three).

• Example:

  • N2I3: Named as Triiodide (due to the prefix tri for three iodine atoms).

  • If the first atom has a subscript greater than one, use the appropriate prefix (e.g. Penta- for five).

• Example:

  • N2O5: Named as Dinitrogen Pentoxide.

Reverse Naming from Given Names

• Given a compound's name, you can derive the formula directly:

  • For example, PCl3 can be derived from its name Phosphorus Trichloride.

  • S2O4 would be derived from its name Disulfur Tetroxide.

Introduction to Acids

• Types of Acids:

  • Binary Acids: Consist of hydrogen and one other nonmetal.

  • Oxoacids: Contain hydrogen, oxygen, and another element (polyatomic ion).

• Naming Binary Acids:

  • Use prefix "Hydro-" followed by the nonmetal's name, change suffix to "-ic," and end with "acid."

  • Examples:

    • HI -> Hydroiodic Acid

    • HCl -> Hydrochloric Acid

    • H2S -> Hydrosulfuric Acid

Naming Oxoacids

• Derived from polyatomic ions:

  • If an ion has an "-ate" ending, name the acid with the same root, change the suffix to "-ic," and add "acid."

  • If an ion has an "-ite" ending, change the suffix to "-ous" and add "acid."

• Examples:

  • HNO3 (Nitrate) -> Nitric Acid

  • HNO2 (Nitrite) -> Nitrous Acid

  • H2SO4 (Sulfate) -> Sulfuric Acid

Calculating Mass Percentages

• Concept: Determine the mass percentage of an element in a compound by dividing the total mass of that element in the compound by the compound's molar mass, then multiply by 100.

• Example:

  • For C2H6: Calculate molar mass (C: 12, H: 1) -> 30 g/mol.

  • Mass percent of Carbon = (2 x 12 / 30) x 100 = 80%.

Moles and Subscripts in Compounds

• The subscript in a chemical formula indicates the number of atoms of an element in one molecule of the compound.

• Example of C4H10: Find moles of hydrogen by multiplying the number of moles of the compound by the subscript.

Real Application of Calculating Moles

• Problem Example: Given a mass of a compound, convert grams to moles then calculate moles of a specific element by using the subscripts from the formula.

• Mass Calculation Example:

  • For Na3PO4: Calculate molar mass (Na: 23, P: 31, O: 16) -> approx. 164 g/mol.

  • Use the number of moles to find grams of a specific element (Na in this case).

Ensuring Accuracy in Calculations

• Always check that the calculated mass of an element cannot exceed the mass of the overall compound to ensure accuracy in computations.

Ionic Compounds vs. Molecular Compounds

Ionic Compounds

• Formed from the electrostatic attraction between metal cations and nonmetal anions.

• Characterized by the transfer of electrons, leading to the formation of charged ions.

• Generally have high melting and boiling points due to strong ionic bonds.

• Typically soluble in water and conduct electricity when dissolved or molten.

Molecular Compounds

• Composed solely of nonmetals, which share electrons through covalent bonds.

• Have lower melting and boiling points compared to ionic compounds due to weaker intermolecular forces.

• Generally do not conduct electricity in any state as they do not form ions.

Naming Molecular Compounds

Naming Convention:

• Name the first element using its full name (e.g., Nitrogen).

• Name the second element, modify its suffix (e.g., Iodine becomes Iodide), and adhere to specific prefix rules to indicate the number of atoms present.

• Common prefixes include:

  • Mono- (1)

  • Di- (2)

  • Tri- (3)

  • Tetra- (4)

  • Penta- (5)

  • Hexa- (6)

  • Hepta- (7)

  • Octa- (8)

  • Nona- (9)

  • Deca- (10)

Examples:

• N₂I₃ is named Triiodide due to the prefix "tri" indicating three iodine atoms.

• N₂O₅ is named Dinitrogen Pentoxide, where "di" indicates two nitrogen atoms and "penta" indicates five oxygen atoms.

Reverse Naming from Given Names

• To derive a formula from a compound's name:

  • Example: Phosphorus Trichloride can be represented as PCl₃, indicating one phosphorus atom and three chlorine atoms.

  • Example: Disulfur Tetroxide corresponds to S₂O₄, indicating two sulfur atoms and four oxygen atoms.

Introduction to Acids

Types of Acids:

1. Binary Acids:

   • Consist of hydrogen and one other nonmetal (e.g., HCl, HF).

   • Properties include being molecular and often weakly ionizing in water.

2. Oxoacids:

   • Contains hydrogen, oxygen, and another element, typically forming from polyatomic ions (e.g., H₂SO₄, HNO₃).

Naming Binary Acids:

• Use prefix "Hydro-" followed by the nonmetal's name and changing the suffix to "-ic," concluding with "acid."

  • Examples:

    • HI is named Hydroiodic Acid.

    • HCl is named Hydrochloric Acid.

    • H₂S is named Hydrosulfuric Acid.

Naming Oxoacids

• Derived from their corresponding polyatomic ions:

  • If an ion ends with "-ate," name the acid using the root of the ion, changing the suffix to "-ic" followed by "acid."

  • If an ion ends with "-ite," alter the suffix to "-ous" and add "acid."

  • Examples:

    • HNO₃ (from Nitrate) is named Nitric Acid.

    • HNO₂ (from Nitrite) is named Nitrous Acid.

    • H₂SO₄ (from Sulfate) is named Sulfuric Acid.

Calculating Mass Percentages

• Concept: To determine the mass percentage of an element in a compound, divide the total mass of that element by the compound's molar mass, then multiply the result by 100 to get a percentage.

Example:

• For C₂H₆:

  • Calculate molar mass where Carbon (C) is 12 g/mol and Hydrogen (H) is 1 g/mol, leading to a total molar mass of 30 g/mol.

  • Thus, the mass percent of Carbon is calculated as:Mass percent of Carbon = ( (2 , \times 12) , / 30 , \times 100 = 80% ).

Moles and Subscripts in Compounds

• The subscript in a chemical formula denotes the number of atoms of each element present in one molecule of that compound.

Example:

• In C₄H₁₀, the number of moles of hydrogen can be found by multiplying the moles of the compound by the subscript 10.

Real Application of Calculating Moles

Problem Example:

• Given the mass of a compound, convert grams to moles, then use the subscripts in the formula to calculate the moles of a specific element.

Mass Calculation Example:

• For Na₃PO₄, calculate molar mass (Na = 23, P = 31, O = 16) yielding an approximate molar mass of 164 g/mol.

• The number of moles helps determine the grams of a specific element, such as Sodium (Na) in this instance.

Ensuring Accuracy in Calculations

• Always verify calculated mass of an element against the total mass of the compound to confirm computational accuracy.

• It is crucial to ensure that mass values logically align with the physical properties of the compound, enhancing reliability in chemical applications.

Ionic Compounds vs. Molecular Compounds in Marvel Terms

Ionic Compounds

• Think of ionic compounds like the Avengers, formed from powerful metal heroes (cations) teaming up with their trusty sidekick nonmetal companions (anions).

• They rely on the dramatic transfer of electrons (like Thor's hammer being passed around) to create a strong bond—a true superhero partnership!

• These compounds have high melting and boiling points (like Iron Man's suit under pressure) and are typically soluble in water (they blend in seamless), conducting electricity when dissolved, just like the Avengers when they unite in battle.

Molecular Compounds

• Imagine molecular compounds as the Guardians of the Galaxy, a team of quirky nonmetal heroes joining together through covalent bonds (like their unique personalities forming friendships).

• They don’t stick together as tightly as the Avengers, which gives them lower melting and boiling points (like a chill day in space).

• And just like the Guardians don’t have electric powers, molecular compounds don’t conduct electricity because they don’t form charged ions.

Naming Molecular Compounds

Naming Convention:

• To name these cosmic compounds, you first name the main hero (like “Rocket”) using their full name.

• Then you name the sidekick, adjusting their title (like “Groot” becoming “Grootoid”) while using comedy prefixes to tell how many there are (like ‘Tri-’ for three).

Examples:

• For N₂I₃, it’s like saying, "Three Groots!"—Triiodide!

• For N₂O₅, think of it as “Two Rockets and Five Um… Things!”—Dinitrogen Pentoxide.

Reverse Naming from Given Names

• If you hear a name like Phosphorus Trichloride (just like crafting a superhero's secret identity), you can draw the formula, PCl₃—easy as pie!

• Disulfur Tetroxide rings out like a Marvel movie—S₂O₄, signifying two Sulfur heroes teaming up with four Oxygen sidekicks.

Introduction to Acids

Types of Acids:

1. Binary Acids:

   • These are like the duo heroes: One hydrogen and one nonmetal (e.g., HCl as Hulk and Black Widow)!

2. Oxoacids:

   • These acid powerhouses consist of hydrogen, oxygen, and another element (like Hulk teaming up with the Avengers!), generally from polyatomic ions (H₂SO₄ like a giant fungus takeover!).

Naming Binary Acids:

• To rename these bad boys, use the prefix “Hydro-” (like Hydro-Man) followed by the nonmetal’s name, switch the ending to “-ic,” and finalize with “acid.”

  • Examples:

    • HI becomes Hydroiodic Acid (like Hydro-Man getting angry!).

    • HCl becomes Hydrochloric Acid (Hydro-Man, but this is a real heavyweight!).

Naming Oxoacids

• Derived from their corresponding polyatomic heroes:

  • If an ion ends with “-ate,” change it to “-ic” (like Hickory changing to Heroic!), followed by “acid.”

  • If it ends with “-ite,” swap to “-ous” and add “acid.”

  • Examples:

    • HNO₃ (like Nitron as Nitric Acid)—boom!

    • H₂SO₄ (Sulfurate turning into Sulfuric Acid) has the power of everything!

Calculating Mass Percentages

• Imagine tracking how much of a hero makes up a team: take their total heroic mass and divide it against the team’s total weight, then multiply by 100 for their percentage share!

Example:

• For a molecule like C₂H₆ (carbon and hydrogen combining forces), figure out their total strengths: Carbon is 12, and Hydrogen is just 1.

  • So, the mass percent of Carbon is 80%, like saying, “90% Hero Power!”

Moles and Subscripts in Compounds

• Each subscript tells us how many heroes (atoms) are in a compound!

Example:

• In C₄H₁₀, the subscripts tell you the number of Hydrogen heroes—10! Like saying, “We have ten sidekicks!”

Real Application of Calculating Moles

Problem Example:

• When relating mass to moles, it’s like taking your team’s total weight and converting it into hero units—then using subscripts to find which hero is on duty!

Mass Calculation Example:

• For Na₃PO₄, calculate the total team weight (Sodium is 23, Phosphorus is 31, Oxygen is 16) yielding a grand total of 164 hero units.

Ensuring Accuracy in Calculations

• Always double-check your calculations to ensure your hero stats align with realism—mass values should reflect their heroic abilities accurately, keeping your superhero chemistry in line!