Chemical Names and Formulas

Chemical Names and Formulas

A. Formulas1. For a molecular compound (only nonmetals), the

formula shows the actual number of atoms of each element in a molecule.

2. For an ionic compound (metal + nonmetal), the formula represents a formula unit (simplest ratio of ions) of the compound.


B. Ions1. Atoms are neutral because they have equal

numbers of protons and electrons.2. Ions- positive or negative particles formed when

atoms lose or gain electrons.3. Cations are positive ions• Metals lose electrons to form (+) ions• Na⁺ Sodium ion lost one electron (e⁻)• Mg²⁺ Magnesium ions lost two electrons

Chemical Names and Compounds

B. Ions 4. Anions are negative ions.

• Nonmetals gain electrons to form (-) ions• Monatomic anions have –ide endings• Cl⁻ chloride ion gained one electron• O²⁻ oxide ion gained two electrons


C. Charge of Ions1. Main Group Elements (8 tall columns)• Group number shows the number of electrons

in the outer energy level (use second digit for group 13 – 18)

• Metals lose all their outer level electrons; nonmetals gain to get 8 outer level electrons.

Group Outer Electrons

Lose/Gain Charge

Na 1 1 Lose 1 1+

Ca 2 2 Lose 2 2+

Al 13 3 Lose 3 3+

C 14 4 Shares None

N 15 5 Gain 3 3-

S 16 6 Gain 2 2-

Br 17 7 Gain 1 1-

Ne 18 8 Unreactive None


D. GroupCharge

1 2 13 14 15 16 17 18

1+ 2+ 3+ 0 3- 2- 1- 0

Li N O F Na Mg Al S Cl

K Ca Br Rb Sr I Cs Ba


2. Transition Metals (short column)a. Also called d-blockb. Most have more than one possible chargec. Use Roman Numerals to show the charge of

transition metals

d. Ag⁺, Zn²⁺, and Cd²⁺ have ONLY one possible charge and don’t get a Roman Numeral.

Fe²⁺ Iron (II) Cu⁺ Copper (I)

Fe³⁺ Iron (III) Cu²⁺ Copper (II)


D. Binary Ionic Compounds1. Contain only two elements (metal + nonmetal)2. (+) and (-) charges MUST balance3. Positive ion (metal) written first4. -ide ending usually indicates a binary compound5.

Sodium Chloride Magnesium Oxide

Calcium Bromide Potassium Oxide

Iron (III) Oxide Lead (IV) Sulfide


6. Naming Binary Ionic Compoundsa. Name of Metal + Name of Nonmetal (-ide)b. CaBr₂ ____________________

Na²O ____________________

c. Use Roman Numerals to show the charge of transition metals (except Ag, Zn, Cd)

CuCl _____________________ CuCl₂ _____________________


E. Polyatomic Ions1. Polyatomic ions- group of atoms that act as one

ion.2. -ite ending indicates one less oxygen than –ate;

the charge will be the same.

SO₄²⁻ SO₃²⁻Sulfate ion Sulfite ion


3. Prefix per- means one more oxygen than -ate; prefix hypo- means one less oxygen than -ite.

CIO₄⁻ PerchlorateCIO₃⁻ ChlorateCIO₂⁻ ChloriteCIO⁻ Hypochlorite

4. H⁺ + CO₃²⁻ => HCO₃⁻Hydrogen Carbonate Hydrogen Carbonate


F. Compounds Containing Polyatomic Ions1. Use parentheses if subscript is added for the

polyatomic ion.2. Sodium Ammonium Carbonate _________ Sulfate _________

Calcium Magnesium Nitrate __________ Hydroxide

__________


G. Binary Molecular Compounds1. Contain two nonmetals2. Same two nonmetals can form several different

compounds.3. Use prefixes in name to show how many atoms

of that element1. Mono- 6. Hexa- 2. Di- 7. Hepta-3. Tri- 8. Octa-4. Tetra- 9. Nona-5. Penta- 10. Deca-


4. CO₂ CO Carbon Dioxide Carbon Monoxide5. Do not use mono- for the first element.6. CBr₄ _______________ N₂O₅ _______________ PCl₃ _______________ N₂O _______________


H. Acids – compounds which produce H⁺ ions in water.

1. Use prefix –hydro where there are only two elements.

2. Anion Endings Acid Name -ide hydro-( )-ic acid -ate ( )-ic acid -ite ( )-ous acid


3. HCl _______________ H₂SO₄ _______________ HNO₃ _______________ Acetic Acid ____________ Phosphoric Acid ________ Carbonic Acid __________4. H₂SO₄ H₂SO₃ Sulfuric Acid Sulfurous Acid


I. Using Chemical Formulas

A. Formula Mass (amu) –sum of the atomic masses of all the atoms in the formula.

B. Molar Mass (g) – the mass of one mole of a substance.

C. Formula mass and molar mass are calculated the same way, but the units are different.


D. Calculate the formula mass and molar mass:Formula Mass Molar Mass

CO₂ ___________ amu ________ g

Ba(NO₃)₂ _________ amu ________ g

Calcium Chloride ___________ amu _________ g

E. Conversions1. Molar Mass 6.022*10²³Grams moles particles

Names Of Particles2. Most elements atoms H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂ molecules Molecular Compounds molecules Ionic Compounds formula units

3. How many moles are in 4.55 grams of magnesium bromide?

4. How many oxygen molecules are in 32 moles of oxygen?

5. Find the mass of 3.4*10²⁵ molecules of methane (CH₄).

6. How many hydrogen atoms are in 89 g of water?

F. Percent Composition – the percent, by mass, of each element in the compound.

1. % composition from lab dataMass of element (100)

1. % element= Mass of compound

2. Calculate % composition if 29.0 grams of silver reacts with 4.30 grams of sulfur to form a compound

3. % Composition from the formulamass of element in 1 mol compound (100)

% element= mass of 1 mol compounds

4. Find the % comp. of magnesium hydroxide.

Chemical Names and CompoundsE. Determining Chemical Formulas- may or may not be correct molecular form.

A. Empirical Formula- Simplest whole number ratio of elements in the compound.

1. Find the empirical formula if 79.8 g carbon reacts with 20.2 g Hydrogen.a. Convert grams to moles of atoms.

b. Find ratio of moles (divide each by the smallest)

c. Empirical Formula

Chemical Names and Compounds2. Find the empirical formula if 25.9% N and

74.1% O.a. Choose to use 100 g compound and convert

grams to moles

b. Find Ratio of moles

c. Need whole number ratio for empirical formula

B. Molecular Formula – shows the actual number of atoms in the molecule

1. Molecular formula = (x) (empirical formula) Molar mass

x= Empirical Mass2. Determine the molecular formula if the empirical formula is CH₂ and the molar mass in 42.0

B. Molecular Formula – shows the actual number of atoms in the molecule

3. Determine the empirical formula and the molecular formula if 58.8% C, 9.8% H, and 31.4% O and the molar mass= 102g

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Chemical Names and Formulas