Unit 1

The Structure of Matter

Units of MeasurementSI Units

Physical Quantity Unit Name Symbol

length meter m

mass kilogram kg

time second s

electric current ampere A

temperature Kelvin K

amount of substance mole mol

luminous intensity candela cd

Metric System Conversions

Generally require temperatures are in Kelvins

T (K) = t (˚C) + 273.15

Generally require temperatures are in Kelvins

T (K) = t (˚C) + 273.15

Temperature Conversions

Celsius

100 ˚C

0 ˚C

100˚C

Kelvin

373 K

273 K

100 K

Fahrenheit

32 ˚F

212 ˚F

180˚F

Three targets with three arrows each to shoot.

Can you hit the bull's-eye?

Both accurate and precise

Precise but not accurate

Neither accurate nor precise

How do they compare?

Can you define accuracy and precision?

• All nonzero numbers and zeros between nonzero digits are significant 

216.4 200.8(four siggy figgies in each)

 • Zeros to the left of the first nonzero number are not significant

 0.000005 0.023

(one siggy figgy and two siggy figgies)• Zeros at the end of a number to the right of the decimal are significant

   276.00 305.0

(five siggy figgies and four siggy figgies)• Zeros at the end of number greater than one are not significant unless their

significance is indicated by the presence of a decimal point

100 100.(one siggy figgy and three siggy figgies)

 

 

Significant Figures

• The coefficients of a balanced equation and numbers obtained by counting objects are infinitely significant

  Using Significant Figures in Computations• When multiplying or dividing – the result should have the same number of

significant figures as the number in the calculation with the smallest number of significant figures.

When adding or subtracting – the result should have the same number of decimal places as the number in the calculation with the smallest number of decimal places.

Why Are Significant Figures Significant?

More Practice

Calculations & Conversion Practice

Determine the length in kilometers if a 5.345 x 1013m automobile race. Watch for significant figures and be sure to include units on your answer. 

Calculations & Conversion Practice

Calculate the mass of 1.0L of benzene if it has a density of 0.879g/mL 

Calculations & Conversion Practice

If the volume of an object is reported as 5.0 cm3, what is the volume in m3? 

Calculations & Conversion Practice

If the volume of an object is reported as 4.5m3, what is the volume in nm3? 

Classification of Matter

 2.6 – Molecules and Molecular Compounds (Covalent Compounds)

•Two or more atoms tightly bound together •Bond by a covalent bond – the sharing of electrons

•Usually nonmetals bonded to other nonmetals

•Elements found in nature in molecular form – N2, O2, F2, Cl2, Br2, I2, H2

•Previous list is called diatomic elements

•Molecular formulas – indicate actual numbers of and types of atoms in a molecule

•Term “molecule” refers only to covalently bonded substances.

•Empirical formulas – smallest possible whole number subscripts

•Use the Greek prefixes to name binary covalent compounds

Prefixes Used in Naming Molecular Compounds

Number Prefix

1 mono-

2 di-

3 tri-

4 tetra-

5 penta-

6 hexa-

7 hepta-

8 octa- ExampleGive the chemical formula for the following: silicon tetrachloride

disulfur dichloride

2.7 – Ions and Ionic Compounds

•Ion – formed when electrons are added or removed from an atom

•Cation – ion with a positive charge – typically metals

•Anion – ion with a negative charge – typically non-metals

•Polyatomic ions – atoms joined as a molecule but have a net positive or negative charge

•Use the periodic table to predict charges

•Formed by the transfer of electrons

•Compounds formed when cations and anions are attracted to each other

•Typically formed by metals and nonmetals

Naming Ionic Compounds•Cations – metals – have the same name as the metal

•Must use roman numerals if dealing with a metal that can have various charges – usually the transition metals

•One atom anions – nonmetals – ending changes to –ide

•Must Memorize the polyatomic chart below!

Dealing With Various Amounts of Oxygen

Example The formula for bromate ion is BrO3

-. What is the formula for hypobromite ion?   

ExampleName the following: NH4Br, Cr2O3, Co(NO3)2

  

ExampleGive the chemical formula for the following:

magnesium sulfate

silver sulfide

lead(II)nitrate

Naming acids

I –ate it and it was –ic

I caught –ite –ous

Binary AcidsHydro ……. -ic

 

ExampleGive the formulas for the following:

1. hydrobromic acid

2. carbonic acid

3. Sulfurous acid

Stoichiometry – the math of chemistry

Law of Conservation of Mass – the total mass of all substances present after a chemical reaction is the same as the total mass before the reaction.

Atomic Theory – atoms are neither created nor destroyed

3.1 – Chemical Equations  Fe (s) + O2 (g) Fe2O3 (s)

  C2H4 (g) + O2 (g) CO2 (g) + H2O(g)

  Al (s) + HCl(aq) AlCl3 (aq) + H2(g)

3-4 – The Mole

1 mol element = 6.02 x 1023 atoms

1mol molecule = 6.02 x 1023 molecules

1 mol ions = 6.02 x 1023 ions

 How many oxygen atoms are in 0.25 mol of Ca(NO3)2?  

How many oxygen atoms are in 1.50 mol of sodium carbonate?

Molar mass(a.k.a gram formula mass)

•The mass of one mole of any substance

•Units are g/mol

•Calculated from periodic table ExamplesCalculate the molar mass of Ca(NO3)2

  How many moles of sodium bicarbonate are there in 508g of sodium bicarbonate?  What is the mass in grams of 6.33 mol of NaHCO3?  What is the mass in grams of 3.0 x 10-5 mol of sulfuric acid?  How many nitric acid molecules are in 4.20g of HNO3? How many oxygen atoms are there?  

3.5 – Empirical and Molecular Formulas ExampleA 5.325 g sample of methyl benzoate, a compound used in the manufacturing of perfumes, is found to contain 3.758g of carbon, 0.316g of hydrogen and 1.251g of oxygen. What is the empirical formula of this substance?  

 ExampleEthylene glycol, the substance uses in automobile antifreeze, is composed of 38.7% carbon, 9.7% hydrogen and 51.6% oxygen by mass. Its molar mass is 62.1g/mol. What is the empirical formula? What is the molecular formula?  

 ExampleCaprice acid, which is responsible for the foul odor of dirty socks, is composed of C, H and O atoms. Combustion of 0.225 g sample of this compound produces 0.512g of CO2 and 0.209g of H2O. What is the empirical formula of caproic acid? The molar mass is 116g/mol. What is the molecular formula?  

3.6 – Quantitative Information Coefficients of balanced equations

•Relative number of molecules

•Relative number of moles

•Use in mole ratio to convert between substances in a stoichiometry calculation 

ExampleThe decomposition of KClO3, is commonly used to prepare small amounts of O2 in the laboratory. 

2KClO3 (s) 2 KCl (s) + 3O2(g) How many grams of O2 can be prepared from 4.50g of KClO3?  

ExamplePropane is a common fuel used in cooking and heating. What mass of O2 is consumed in the combustion of 1.00g of propane?  

3.7 – Limiting Reagents Limiting reactant or reagent • Reactant that is completely consumed in a chemical reaction

 Theoretical Yield • Amount of product you would get in a perfect experiment (determined mathematically)

 Actual yield• What you actually get during the experiment (determined experimentally)

   

ExampleA strip of zinc metal massing 2.00g is placed in an aqueous solution containing 2.50g of silver nitrate, causing the following reaction to occur:

Zn (s) + 2 AgNO3 (aq) 2 Ag(s) + Zn(NO3)2 (aq)

Which reactant is limiting? How many grams of Ag will form? How many grams of Zn(NO3)2 will form? How many grams of excess reactant will be left at the end of the reaction?   

Example – Percent Yield ProblemImagine that you are working on ways to improve the process by which iron ore containing Fe2O3 is converted into iron. In your tests you carry out the following reactions on a small scale:

Fe2O3 (s) + 3 CO (g) 2Fe(s) + 3CO2 (g)

If you start with 150g of Fe2O3 as the limiting reagent, what is the theoretical yield of Fe? If the actual yield of Fe in your test was 87.9g, what is your percent yield?   

2Al (s) + 3 Cl2 (g) 2 AlCl3 (s)

A mixture of 1.50 mol Al and 3.00 mol Cl2 are allowed to react. What is the limiting reagent? How many moles of AlCl3 are formed? How many moles of excess reagent remain at the end of the reaction?