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Basic Concepts

100

What is an ionic compound? Provide an example.

An ionic compound is a chemical compound composed of positively charged cations  (metal)  and negatively charged anions (non-metal)  , held together by ionic bond . Example: Sodium chloride (NaCl).

200

What is a binary compound?  Give an Example.

A binary compound is a chemical compound composed of only two elements. 

Magnesium oxide (MgO).

300

Write the names of the following compounds: CaO, KBr, Al₂O₃. 

Calcium oxide, 

potassium bromide, 

aluminum oxide.

400

Write the chemical formulas for the following compounds: magnesium oxide, aluminum chloride, potassium sulfide.

Magnesium oxide → MgO

Aluminum chloride → AlCl₃

Potassium sulfide → K₂S

500

Explain the role of superscripts (charge notation) and subscripts (quantity of atoms) in chemical formulas.

• Superscripts represent the charge of an ion (e.g., Na⁺, O²⁻).
• Subscripts indicate the number of atoms in a chemical formula (e.g., H₂O has 2 hydrogen atoms and 1 oxygen atom).

Naming & Balancing Ionic Compounds

100

What is the name of NaCl?

Sodium chloride.

200

What is the chemical formula for potassium bromide?

KBr.

300

Calculate the ion ratio in CaCl₂ and explain why it needs to be balanced.

• Calcium ion (Ca²⁺) has a +2 charge, and chloride ion (Cl⁻) has a -1 charge.
• To balance the charges, two Cl⁻ ions are needed for every Ca²⁺ ion, forming CaCl₂.

400

Why do multivalent metals (e.g., Fe) require Roman numerals in their names?

Multivalent metals can have multiple states. Roman numerals indicate which charge is used in a compound. Example: FeCl₂ = Iron(II) chloride, FeCl₃ = Iron(III) chloride.

500

Write the chemical formula for iron(III) oxide and explain the electron transfer process.

• Iron(III) means Fe³⁺ (3+ charge).
• Oxygen forms O²⁻ (2- charge).
• To balance charges, we need 2 Fe³⁺ ions and 3 O²⁻ ions, forming Fe₂O₃.

Polyatomic Ions & Multivalent Metals

100

What is a polyatomic ion? Provide an example.

A polyatomic ion is an ion composed of two or more atoms covalently bonded, carrying a net charge. Example: Nitrate (NO₃⁻).

200

Write the chemical formula for potassium nitrate

KNO₃.

300

Copper (Cu) can form two common ions. What are they, and how are their compounds named? Write Examples.

• Cu⁺ → Copper(I)
• Cu²⁺ → Copper(II)
• Example: Cu₂O = Copper(I) oxide, CuO = Copper(II) oxide

400

Why do we use parentheses in Mg(NO₃)₂? 

• Mg²⁺ needs two NO₃⁻ ions to balance the charge.

• Since NO₃⁻ is a polyatomic ion, parentheses are used when there’s more than one of them.

500

Write the chemical formula for calcium phosphate and explain its ionic composition.

Calcium ion: Ca²⁺

Phosphate ion: PO₄³⁻

To balance charges, three Ca²⁺ ions and two PO₄³⁻ ions are needed, forming Ca₃(PO₄)₂.

Naming Covalent Compounds

100

What is a covalent compound? Provide an example.

A covalent compound is a chemical compound where atoms share electrons. Example: Water (H₂O).

200

What is the correct name for CO₂?

Carbon dioxide.

300

Write the name of P₄S₁₀ and explain the use of prefixes.

• P₄S₁₀ = Tetraphosphorus decasulfide
• Prefixes indicate the number of atoms: "tetra-" = 4, "deca-" = 10.

400

Write the names of SO₃ and FeCl₃, and explain how they differ.

• SO₃ = Sulfur trioxide (a covalent compound, uses prefixes).
• FeCl₃ = Iron(III) chloride (an ionic compound, uses Roman numerals).

500

Compare the naming rules of binary covalent compounds and binary ionic compounds.

• Covalent compounds: Use prefixes (mono-, di-, tri-, etc.). Example: CO₂ = Carbon dioxide.
• Ionic compounds: No prefixes, but Roman numerals for multivalent metals. Example: FeCl₂ = Iron(II) chloride.

Writing Chemical Formulas

100

Write the chemical formula for barium fluoride.

BaF₂.

200

What is the chemical formula for magnesium oxide?

MgO

300

Write the chemical formula for dinitrogen tetroxide.

N₂O₄.

400

What is the chemical formula for iron(III) sulfate?

Fe₂(SO₄)₃.

500

Based on the name "Lead(IV) sulfide," write the correct chemical formula and explain how charge balancing works.

• Lead(IV) means Pb⁴⁺.
• Sulfide ion is S²⁻.
• To balance, we need 2 S²⁻ for every 1 Pb⁴⁺, forming PbS₂.