chem: ch 3

stoichiometry

ionic compound

made of metal and non-metal ions

covalent compound

made of only non-metal atoms

oxidation state

a number assigned to an atom in a compound that represents the total number of electrons it has lost or gained, indicating its degree of oxidation

chemical formula

includes types and numbers to show the ratio or exact count of atoms

molecular formula

a specific chemical formula that shows the actual number of atoms of each element in a single molecule of a covalent compound

diatomic molecules

H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂, At₂

how do you deduce the formula of an ionic compound?

balance the charges so the total positive charge of the cations equals the total negative charge of the anions, resulting in a neutral compound (overall charge of zero)

positive ions

1. ammonium ion, NH_4⁺

2. silver ion, Ag⁺

3. copper ion, Cu²⁺

4. iron (II) ion, Fe²⁺

5. lead ion, Pb²⁺

6. manganese ion, Mn²⁺

7. nickel ion, Ni²⁺

8. zinc ion, Zn²⁺

9. chromium ion, Cr³⁺

10. iron (III) ion, Fe³⁺

polyatomic ion

a covalently bonded group of 2+ atoms that acts as a single ion with a specific charge

negative polyatomic ions

1. hydroxide ion, OH^-

2. manganate (VII), MnO₄^-

3. nitrate ion, NO₂^-

4. nitrate ion, NO₃^-

5. carbonate ion, CO₃^2-

6. dichromate (VI), Cr₂O₇^2-

7. sulfate ion, SO₃^2-

8. sulfate ion, SO₄^2-

9. phosphate, PO₄^3-

superscript

charge of ion

subscript

number of atoms

formulae

• acids

1. hydrochloric acid, HCI

2. nitric acid, HNO₃

3. phosphoric acid, H₃PO₄

4. sulfuric acid, H₂SO₄

• ammonia, NH₃

• water, H₂O

stoichiometry

to determine the proportions in which elements/compounds react with one another based on the laws of conservation of mass and energy (same elements present on both sides of the equation)