Chem 1310, Some Common Polyatomic Ions

Double-replacement reaction

(also known as double-displacements or metathesis reactions), two ionic compounds exchange ions to form two new compounds

Single-replacement reactions

(also known as single-displacement or displacement reactions) occur when an element reacts with a compound and displaces one of the elements in that compound, producing a new compound and a new element.

Synthesis reactions

(or combination reactions)start with simple reactants that combine to form a single more complex product.

Compounds can exist in different forms.

- Molecular compounds or covalent compounds • Exist as individual particles made up of bonded atoms. -Ionic compounds •Exist not as individual particles but as extended, 3D lattice structures .

Ions

- Species with a net charge. The numbers of protons and electrons in the species are not equal. Anions- Have more electrons than protons Cations - Have more protons than electrons •Ions can be either monatomic (derived from a single atom) or polyatomic (a group of atoms with an overall charge).

Chemical formula

-Describes compounds in terms of their atomic substituents

A note on vocabulary:

-Formula weight or formula mass are generic terms that may refer to atoms, molecules or ionic compounds. •Most frequently used for ionic compounds since they do not exist as individual molecules. -Atomic weight or atomic mass refers to atoms -Molecular weight or molecular mass refers to molecules -Molar mass can be used to refer to the mass of one mole of atoms, molecules, or formula units of ionic compounds. •Few chemists actually use the terms formula weight or formula mass and use molar mass and molecular weight somewhat interchangeably.

Consider theobromine, the active ingredient in chocolate: C₇H₈N₄O₂

-If you eat onemolecule of theobromine, then you've consumed 7 atoms of C. -What if you eat one mole of theobromine? Did you still consume only 7 atoms of C? •No! You consumed one mole of molecules, and there are 7 atoms of C per molecule. So, you consumed 7 moles of C atoms!We can derive mole ratios from chemical formulas.

•Molecular formula

-The complete inventory of atoms

•Empirical formula

-The lowest whole number ratio of atoms in a compound

Atomic Masses (2.5)

-The mass of one isotope of one element was assigned a value, and the masses of all other atoms are measured relative to that standard. •Atomic mass -The weighted average of the masses of the naturally occurring mixture of isotopes of an element, compared with one-twelfth of the mass of a 12C atom

Ionizable hydrogen atoms

-The term for the H atoms that are released in water. -Typically, written at the beginning of the formula.

Pressure

1 atm = 760 Torr 1 atm = 760 mmHg 1 atm = 101325 Pa 1 atm = 14.7 psi 1 atm = 1.01325 bar 1 bar = 100 kPa 1 Torr = 1 mmHg

Energy

1 cal = 4.184 J 1 L·atm = 101.325 J 1 eV = 1.602×10-19 J 1 J = 1 kg·m2/s2 1 J = 1 m3·Pa 1 J = 1 L·kPa 1 J = 1 C·V

Length

1 in = 2.54 cm (exact) 1 Å = 1×10-10 m 1 mi = 5280 ft 1 mi = 1609.3 m 1 ft = 0.3048 m 1 m = 1.094 yd 1 km = 0.621 miles(mi)

Mass

1 lb = 453.6 g 1 g = 6.022×1023 amu 1 kg = 2.20 lb 1 lb = 16 oz 1 oz = 28.35 g 1 ton = 2000 lb 1 metric ton = 1 Mg

Volume

1 mL = 1 cm3 1 L = 1.0567 qt 1 gal = 3.7854 L 1 m3 = 1000 L

Chemical equations can be balanced using this four-step strategy:

1.Balance polyatomic ions as units if they are present as both reactants and products. 2.Balance elements that appear in only one reactant and one product. 3.Balance any remaining elements; resolve odd/even issues by doubling previously determined coefficients. 4.Verify that the number of each type of atom is the same in the reactants and products and that the coefficients are in the simplest form.

Steps in determining an empirical formula

1.Convert percent data into mass data, assuming 100.0 g sample. 2.Convert the mass of each element into moles of each element. 3.Divide moles of all elements by the smallest number of moles. 4.If not whole numbers, multiply by an appropriate factor. 5.Insert the numbers as subscripts in the formula.

How many grams of solute are present in 575 mL of 0.150 M KBr?

10.2

If 3.20 mol of C₅H₁₂ reacts with excess O₂, how many moles of CO₂ will be produced by the following combustion reaction? C₅H₁₂ + 8O₂ → 6H₂O + 5CO₂

3.20 x 5 = 16 moles of CO₂: 16

Assuming an efficiency of 43.00%, calculate the actual yield of magnesium nitrate formed from 126.8 g of magnesium and excess copper(II) nitrate. Mg+Cu(NO₃)₂⟶Mg(NO₃)₂+Cu

332.6

Rutherford's nuclear model

:•The atom's positive charge and the majority of its mass are located in a relatively small area, the nucleus. •The vast majority of the atom is empty space. Small, negatively charged electrons are spread throughout this empty space. •The number of negatively charged electrons is equal to the number of positively charged particles (protons) inside the nucleus.

What is the charge of the cation in the compound Al₂(SO₄)₃? A) 3+ B) 2+ C) neutral - no charge D) 2- E) 3-

A)

Consider the following reaction: 2 NO(g) + 5 H₂(g) → 2 NH₃(g) + 2 H₂O(g) A reaction mixture initially contains 5 moles of NO and 10 moles of H₂. How much (in moles) is present of each substance after the reaction goes to completion? A) 1 mol NO, 0 mol H₂, 4 mol NH3, 4 mol H2O B) 1 mol NO, 0 mol H₂, 5 mol NH₃, 5 mol H₂O C) 0 mol NO, 1 mol H₂, 4 mol NH₃, 4 mol H2O D) 0 mol NO, 1 mol H₂, 5 mol NH₃, 5 mol H₂O E) 3 mol NO, 5 mol H₂, 2 mol NH₃, 2 mol H₂O

A) 1 mol NO, 0 mol H₂, 4 mol NH3, 4 mol H2O

A sample of CH₂F₂ with a mass of 19.0 grams contains how many atoms of fluorine? A) 4.40 x 10²³ fluorine atoms B) 8.13 x 10¹⁹ fluorine atoms C) 2.20 x 10²³ fluorine atoms D) 2.24 x 10⁻²⁸ fluorine atoms E) 4.08 x 10²³ fluorine atoms

A) 4.40 x 10²³ fluorine atoms

Which of the following is best described as an ionic compound? A) CCl₄ B) SrI₂ C) NO₃- D) N₂O₄ E) There is no general rule to predict if a bond will be classified as ionic

B)

There are two types of acids: binary acids and oxyacids.

Binary acid: HCl •Releases one H+ to form Cl- •Monoprotic: one ionizable H atom Oxyacid: H2SO3 •Releases one H+ to form HSO3- •HSO3- releases another H+ to form SO32- •Polyprotic:more than one ionizable H atom

Which of the following best describes the reaction listed below? 2KI(aq) + Pb(NO₃)₂(aq) → PbI₂(s) + 2KNO₃(aq) A) Aqueous potassium iodate reacts with aqueous lead(II) nitrite to form solid lead(II) iodate and aqueous potassium nitrite. B) Aqueous potassium(I) iodide reacts with aqueous lead(II) nitrate to form solid lead(II) iodide and aqueous potassium(I) nitrate. C) Aqueous potassium iodide reacts with aqueous lead(II) nitrate to form solid lead(II) iodide and aqueous potassium nitrate. D) Aqueous potassium(I) iodate reacts with aqueous lead(II) nitrite to form solid lead(II) iodate and aqueous potassium(I) nitrite. E) Aqueous potassium iodide reacts with aqueous lead(II) nitrite to form solid lead(II) iodite and aqueous potassium nitrite.

C) Aqueous potassium iodide reacts with aqueous lead(II) nitrate to form solid lead(II) iodide and aqueous potassium nitrate.

You measure out 63.55 g of copper in lab. Which of the following statement(s) is(are) true? I. The sample contains one mole of copper atoms. II. There are 6.022 x 1023 Cu atoms present in the sample. III. All atoms in the sample have 36 neutrons. A) I only B) II only C) Both I and II D) Both I and III E) I, II and III

C) Both I and II

Cyanide

CN⁻

Carbonate

CO₃²⁻

Hypochlorite

ClO⁻

Chlorite

ClO₂⁻

Chlorate

ClO₃⁻

Perchlorate

ClO₄⁻

Combustion analysis

Combustion analysis is a lab technique used to determine the empirical formula of compounds containing C, H, and perhaps O. •A known mass of the sample reacts with oxygen. -All carbon ends up as CO2. -All hydrogen ends up as H2O. -The masses of CO2 and H2O are measured and used to determine mass of C and H in the original sample.

Weak bases

Covalent compounds with structures like ammonia, NH₃ React with water to a small extent to produce OH⁻ ions and cations - Form solutions that conduct electricity only slightly and are weak electrolytes

Chromate

CrO₄²⁻

Dichromate

Cr₂O₇²⁻

Acetate

C₂H₃O₂⁻

What is the correct symbol for an isotope that has 16 protons, 16 neutrons and 18 electrons? A) ¹⁶O²⁻ B) ¹⁶O C) ³²S D) ³²S₂⁻ E) ³²Ar

D)

10.1 grams of magnesium is reacted with excess oxygen to produce magnesium oxide and 11.9 g of MgO was collected. What is the percent yield for the reaction? 2Mg(s) + O₂(g) → 2MgO(s) A) 8.37% B) 51.2% C) 70.4% D) 71.1% E) 141%

D) 71.1%

There are two samples of different pure substances. Sample one is three moles of calcium sulfate. Sample two is three moles of calcium sulfide. Which of the following statement(s) is (are) true? A) The number of calcium ions in sample 1 equals the number of calcium ions in sample 2 B) There are more moles of sulfur in sample 2 than in sample 1 C) There are 1.807 x 10²⁴ formula units in sample 1 D) A and C only E) All the statements (A, B, C) are correct

D) A and C only

What is the empirical formula of a compound that contains 34.55% magnesium, 19.93% silicon, and the remainder oxygen by mass? A) MgO₃ B) MgSiO₃ C) Mg₂SiO₂ D) Mg₂SiO₄ E) There is not enough information given; I need the molar mass of the compound

D) Mg₂SiO₄

Dalton's early model

Dalton's early model (a) consisted of an indivisible sphere. Thomson's plum-pudding model (b) consisted of negatively charged electrons suspended in a larger sphere of positive charge. British scientist Ernest Rutherford's gold foil experiment was designed to substantiate Thomson's plum-pudding model. Instead, it led to a new nuclear model of the atom.

Strong electrolytes

Dissociate completely Soluble ionic compounds, strong acids, strong bases, good conductors

Weak electrolytes

Dissociate only a little Weak acids/weak bases, poor conductors

Which of the following name/formula combinations are incorrect? Name Formula A) lead(II) phosphate Pb₃(PO₄)₂ B) phosphorous trioxide PO₃ C) ammonium hydrogen carbonate NH₄HCO₃ D) iron(III) ion Fe³⁺ E) All of the name/formula combinations above are correct.

E) All of the name/formula combinations above are correct.

Average atomic mass

For an element can be found on the periodic table along with the atomic number. -Also called atomic mass, atomic weight, or average atomic weight. Atomic mass: (fraction of isotope) x (Mass of isotope)

Example: How many neutrons are there in an atom of the isotope 60 Co?

From the periodic table, the atomic number of Co is 27.-Mass number = 60-Atomic number = protons = 27- Neutrons = mass number - atomic number-Neutrons = 60 - 27 = 33 * Note: We often think of "isotope" in terms of radioactivity. Not all isotopes are radioactive, but 60Co happens to be. Its radioactivity is exploited in GammaKnifeTM surgery to treat brain tumors.

General Solubility Guidelines

General Solubility Guidelines Compounds of Group 1 elements (Li+, Na+, K+, Rb+, Cs+, and Fr+) or ammonium (NH4+) are soluble. Nitrates (NO3-), chlorates (ClO3-), perchlorates (ClO4-), and acetates (C2H3O2-) are soluble. Chlorides (Cl-), bromides (Br-), and iodides (I-) are soluble except for those of Ag+, Pb2+, and Hg22+. With the exception of rule 1, most carbonates (CO32-), chromates (CrO42-), phosphates (PO43-), and sulfites (SO32-) are insoluble. With the exception of rule 1 and the barium ion (Ba2+), hydroxides (OH-) and sulfides (S2-) are insoluble*. With the exception of rule 2, silver (Ag+), mercury (Hg22+), and lead (Pb2+) salts are insoluble. With the exceptions of compounds of calcium (Ca2+), strontium (Sr2+), barium (Ba2+), and the ions listed in rule 6, all sulfates are soluble. *Calcium chromate and calcium and strontium hydroxide are classified as slightly soluble, or even soluble in some textbooks. **Magnesium sulfide decomposes in water. ***Most of the oxides of Groups 1 and 2 react with water to form hydroxides.

Groups and Periods

Groups-The vertical columns of the periodic table -The modern periodic table labels the groups 1-18. Older versions use 1A-2A for the main group elements and 1B-8B for the transition metals. Roman numerals also are used frequently in older versions. •Periods-The horizontal rows of the periodic table

Hydrogen carbonate (or bicarbonate)

HCO₃⁻

Hydrogen phosphate

HPO₄²⁻

Dihydrogen phopshate

HPO₄⁻

Hydrogen Sulfite (or bisulfite)

HSO₃⁻

Hydrogen Sulfate

HSO₄⁻

Example:

How many protons and electrons are there in the chlorine atom? In the chlorine ion (Cl-)?-Chlorine atom = Cl-From the periodic table, Cl has 17 protons. In the neutral atom, there are also 17 electrons.-Chloride ion = Cl--The chlorine atom gained one electron to form an anion. The chloride ion thus has 17 protons and 18 electrons.

There are only seven strong acids. ALL other acids are weak

Hydrochloric acid: HCl: H⁺, Cl⁻ Hydrobromic acid: HBr: H⁺, Br⁻ Hydroiodic acid: HI: H⁺, I⁻ Nitric acid: HNO₃: H⁺, NO₃⁻ Perchloric acid: HClO₄: H⁺, ClO₄⁻ Chloric acid*: HClO₃: H⁺, Clo₃⁻ Sulfuric acid**: H₂SO₄: H⁺, HSO₄⁻ *Considered weak in some sources ** Only the first deprotonation is complete

Seven elements occur as diatomic molecules when they are in their elemental form.

Hydrogen Nitrogen Oxygen Fluorine Chloride Bromine Iodine

Strong bases

Ionic compound containing hydroxide ions and dissociate 100% in water -Form solutions that conduct electricity very well and are strong electrolytes

Strong acids

Ionize nearly 100% -Form solutions that conduct electricity very well and are strong electrolytes

Weak acids

Ionize only partially less than 100% -Form solutions that conduct electricity only slightly and are weak electrolytes

Example:A given compound is 41.39% C and 3.47% H by mass. The rest of the compound is composed of O. The molecular weight of the compound is 116.28 g/mol. What is its molecular formula?

Mass of O: 100.0% - 41.39% C - 3.47% H = 55.14% O •Assume 100.0 g of substance:41. 39 g C, 3.47 g H, and 55.14 g O •Use molar mass to convert g of each substance to moles

Cryolite, Na₃AlF₆(s), an ore used in the production of aluminum, can be synthesized using aluminum oxide. Balance the equation for the synthesis of cryolite. Al₂O₃(s)+NaOH(l)+HF(g)⟶Na₃AlF₆+H₂O(g) If 16.9 kg of Al₂O₃(s),16.9 kg of Al₂O₃(s), 55.4 kg of NaOH(l),55.4 kg of NaOH(l), and 55.4 kg of HF(g)55.4 kg of HF(g) react completely, how many kilograms of cryolite will be produced Mass of cryolite produced: What reactants will be in excess: What is the total mass of the excess reactants left over after the reaction is complete? total mass of excess reactants:

Mass of cryolite produced: What reactants will be in excess: What is the total mass of the excess reactants left over after the reaction is complete? total mass of excess reactants: Al2O3 + 6 NaOH + 12 HF ? 2 Na3AlF6 + 9 H2O(17.5 kg Al2O3) / (101.9614 g Al2O3/mol) x (2/1) = 0.343 kmol Na3AlF6(51.4 kg NaOH) / (39.9971 g NaOH/mol) x (2/6) = 0.428 kmol Na3AlF6(51.4 kg HF) / (20.0064 g HF/mol) x (2/12) = 0.428 kmol Na3AlF6 Since Al2O3 produces the least amount of product, Al2O3 is the limiting reactant. NaOH and HF are in excess.(0.343 kmol Na3AlF6) x (209.9413 g/mol) = 72 kg Na3AlF6 produced (17.5 kg Al2O3) / (101.9614 g Al2O3/mol) x (6/1) x (39.9971 g NaOH/mol) =41.2 kg NaOH reacted(17.5 kg Al2O3) / (101.9614 g Al2O3/mol) x (12/1) x (20.0064 g HF/mol) =41.2 kg HF reacted(51.4 kg NaOH initially - 41.2 kg NaOH reacted) +(51.4 kg HF initially - 41.2 kg HF reacted) = 20.4 kg total excess reactants left over

Permanganate

MnO₄⁻

Nitrogen and hydrogen combine at a high temperature, in the presence of a catalyst, to produce ammonia. N₂(g) + 3H₂(g) --> 2NH₃(g) There four molecules of nitrogen and nine molecules of hydrogen present in the diagram. When the reaction is complete, how many molecules of NH₃ are produced?

Molecules of NH₃: 6 What is the limiting reactant: hydrogen How many molecules of each reactant remain after the reaction is complete: molecules of H₂: 0 molecules of N₂: 1

Small quantities of oxygen can be prepared in the laboratory by heating potassium chlorate, KClO3(s) The equation for the reaction is 2KClO₃⟶2KCl+3O₂ Calculate how many grams of O₂(g)can be produced from heating 79.6 g KClO3(s).

Moles of KClO₃ = 93.9/ 122.55 = 0.7662 Moles of O₂ = ( 3/2) x KClO3 moles = ( 3/2) x 0.7662 = 1.1493 Mass of O₂ = 1.1493 x 32 = 36.78 gm

Ammonium

NH₄⁺

Nitrite

NO₂⁻

Nitrate

NO₃⁻

Nonelectrolytes

No dissociation Molecular (aka) covalent compounds, no conductivity

Atoms are electrically neutral:

Number of protons = number of electrons •Atomic numberis the number of protons in the nucleus of an atom. -All atoms of a given element have the same number of protons (the atomic number identifies the element). 14Subatomic Particles, Isotopes, and Ions (2.4)

Hydroxide

OH⁻

Peroxide

O₂²⁻

Phosphate

PO₄⁻³

Subatomic Particles, Isotopes, and Ions (2.4)

Protons, neutrons, and electrons are subatomic particles .•The nucleus comprises almost all of the mass of an atom whereas most of the volume is occupied by electrons.

Reactions occur

Reactions occur spontaneously due to a combination of changes in heat energy and randomness, which are discussed in future chapters. •Certain patterns of reactants and products tend to be associated with spontaneous reactions and can be classified by their driving force: 1) Formation of a precipitate 2) Formation of water (neutralization) 3) Oxidation and reduction

Sulfite

SO₃²⁻

Sulfate

SO₄²⁻

Significant Figures

Scientists imply the level of precision in measurements by how they report the number. Unlike in mathematics where 25 and 25.0 are identical, a measurement of 25 cm in science means something drastically different than a measurement of 25.0 cm.Scientific measurements are reported to one digit more than what is known with certainty. A reported value of 25 cm implies that the actual value is somewhere between 24 cm and 26 cm, approximately. In contrast, a reported value of 25.0 cm implies that the actual value is somewhere between 24.9 cm and 25.1 cm, approximately. Counting Significant FiguresTo know which digits in a number are "significant", first let's go over some terminology. Non-zero digits are 1, 2, 3, 4, 5, 6, 7, 8, and 9 (any digit other than zero). Leading zeros are those that come before all the non-zero digits (but not necessarily before the decimal point). Trailing zeros are those that come after all the non-zero digits (but not necessarily after the decimal point).Rule 1: Non-zero digits are always significant. For example, 25 has two significant figures.Rule 2: Leading zeros are never significant. For example 0.025 has two significant figures.Rule 3: Trailing zeros are significant if a decimal point is shown in the number, but may or may not be significant if no decimal point is shown. By convention, it is assumed that trailing zeros without a decimal point are not significant. For example, 250.0 has four significant figures, but 2500 only has two definitive significant figures. In these cases, it is best to write the number in scientific notation to avoid ambiguity.Rule 4: Zeroes that are between non-zero digits are always significant. RoundingYou will often need to round calculated numbers to the proper number of significant figures. For example, 25.18 rounded to one significant figure is 30, rounded to two significant figures is 25, and rounded to three significant figures is 25.2.How would you round a number like 99.99 to three significant figures? You could either write 100. or 1.00×102. Multiplication and Division of MeasurementsThe number of significant figures in the product or quotient of two or more measurements cannot be greater than that of the measurement with the fewest significant figures. For example: 25.0 × 1.0 = 25 Addition and Subtraction of MeasurementsThe number of digits after the decimal point in the sum or difference of two or more measurements cannot be greater than that of the measurement with the fewest digits after its decimal point. For example: 25.0 + 1 = 26 Logarithms and Antilogs The number of digits after the decimal point of log(x) should be equal to the number of significant figures of x. For example: log (3.5×105) = 5.54 For an inverse log of x (10x), the number of significant figures in the answer should be equal to the number of digits after the decimal point in x. For example: 10-3.421 = 3.79×10-4 Multi-step CalculationsWhen doing a series of mathematical operations, you should not round at each individual step. You should keep track of the number of significant figures produced at each step, then round at the end.For example: (30.62 ÷ 2.0) + 0.4 = 16To arrive at this answer, you would first analyze each step...1) 30.62 ÷ 2.0 = 15.31. If rounded, the result would have only have two significant figures, and thus no digits after the decimal point.2) Take the unrounded value, 15.31, and add 0.4. 15.31 + 0.4 = 15.71. From step 1, we know the result should have no digits after the decimal point, and so we round to the ones place, 15.71 ≈ 16.You may be wondering, "Why is 16 a better answer than 15.71? Isn't the number more accurate with more digits?". But remember, the original values (30.62, 2.0, and 0.4) each have some degree of error in them (since nearly everything in science is a measurement). If we report the answer as 15.71, we imply that we know it's between 15.70 and 15.72, and that is simply not true. The accumulated error puts the ones place in doubt, so by reporting the answer as 16 we imply that it's roughly between 15 and 17.

Soluble and Insoluble

Soluble: Dissolves easily and to a large extent Insoluble: Substances do NOT dissolve to any appreciable extent Solubility rules are a quick way to see what substances are soluble or insoluble

Components of a solution: Solvent: Solute:

Solvent: Component present in a greater amount Solute: Component present in a lesser amount

Electrolytes

Substances that dissolve in water to produce a conductive solution

Temperature

TK = TC + 273.15 TC = (5/9)(TF - 32) TF = 32 + (9/5)TC

Percent Composition

Tells us what percentage (by mass) of a compound is made up by each element in the compound - May be calculated using formula masses (atomic mass units) or molar mass (g/mol)

When ionic compounds dissolve, they dissociate or break apart into their constituent ions

The associated reaction is called a dissociation reaction Dissociation cannot without dissociation Dissolution frequently happens without dissociation Sugar is covalent so it does not dissociate in water, but it does dissolve, Water and NaCl will cause dissociation Uneven distribution of electron within water molecules cause oxygen side of water to have a partial negative charge and the H-side to have a partial positive charge Attraction between partial charges and ions result in dissociation. Resulting ions are hydrated

Atomic mass

The atomic mass of each element is the average mass of one atom, expressed in atomic mass units, amu (or u in some texts) One atomic mass unit, amu, is equal to 1g divided by Avogadro's number

The Ostwald process is used commercially to produce nitric acid, which is, in turn, used in many modern chemical processes. In the first step of the Ostwald process, ammonia is reacted with oxygen gas to produce nitric oxide and water. What is the maximum mass of H₂O that can be produced by combining 51.0g of each reactant 4NH₃(g)+5O₂(g)⟶4NO(g)+6H₂O(g)

The first step reaction of Ostwald process: 4NH₃(g)+5O₂(g)⟶4NO(g)+6H₂O(g) Given masses of reactants: m(NH₃) = 51.0 g (O₂) = 51.0 g Calculated molar masses: M(NH3) = 17 g/mol M(O2) = 32 g/mol M(H2O) = 18 g/mol Amounts of reactants:n = m/Mn(NH3) = 51/17 = 3 moln(O2) = 51/32 = 1.59 moles is obviously (accourding to the chemical reaction coefficients) that 4 moles of NH3 react with 5 moles of O2completely. But we have 3 and 1.59 moles respectively, so NH3 is in abundance. So, all calculations will be made using the amount of oxygen. 5 moles of O₂ give 6 moles of H₂O 1.59 moles of O₂ give moles of H₂Ox= 1.59×6/5 = 1.908 mol. The mass of water formed is m = nM = 1.908×18 =34.34 Answer: 34.3 g

The molecular formula

The molecular formula gives the actual number of atoms of each element in one molecule of a covalent compound. -For example, one molecule of glucose, C₆H₁₂O₆, contains 6 C atoms, 12 H atoms, and 6 O atoms. -The molecular formula is always an integer (whole-number) multiple of the empirical formula.

The periodic table is an organization of elements by

The periodic table is an organization of elements by increasing atomic number with elements having similar chemical properties aligned in vertical columns.

Aqueous Solutions

When something dissolves in water NaCl(aq)

Acid-base reactions

are a special case of double-replacement reactions -An acid is a type of compound usually written with H at the beginning of its formula. -A base is a type of compound often written with OH at the end of its formula because many bases are hydroxide compounds.

Acids

are a special class of hydrogen-containing covalent compounds that, when dissolved in water: -Release one or more H+ ions -Form an anion with a -1 charge for each H+ ion that was released.

Isotopes

are atoms of the same element that have different numbers of neutrons. •C-14 has a mass number of 14 while C-12 has a mass number of 12. •C-14 has 14 - 6 = 8 neutrons while C-12 has 12 - 6 = 6 neutrons.

Polyatomic ions

are groups of two or more bonded atoms that have lost or gained electrons, and thus have an overall net charge Ionic compounds containing polyatomic ions are named the same way as other ionic compounds, except that we use the name of the polyatomic ion whenever it occurs. -Do not change the ending of the polyatomic anion's name

Chemical formulas

combine elemental symbols and subscripts to represent chemical compounds. -Provide information about the relative number of atoms of each element -Sometimes also give information about the arrangement of atoms in the molecule. The group of atoms represented by a chemical formula is called a formula unit. -An atom or molecule of an uncombined element, a molecule of a covalent compound, or a set of ions in an ionic compound

Binary acids

contain H atoms and atoms of an element from group 6A or 7A.

Oxyacids

contain hydrogen atoms bonded to oxyanions (polyatomic ions containing oxygen).

English physicist J.J. Thomson

discovered the negatively charged subatomic particle now known as the electron in the late 1800s.•American physicist Robert Millikan succeeded in measuring the mass of a single electron in the early 1900s.-Because atoms are neutral overall, the "non-electron" part of the atom must have a positive charge equal to the negative charge of electrons.-The electron accounted for only 1/1836 of the mass of a hydrogen atom.-These observations led to Thomson's plum-pudding model of the atom.

JohnDalton

formulated his atomic theory to explain the laws of chemical combination: 1.Matter is made up of very tiny, indivisible particles called atoms. 2.Each atom of a particular element has the same mass, but the mass of an atom of one element is different from the mass of an atom of any other element. 3.Atoms combine to form what we now call molecules. When they do so, they combine in small, whole-number ratios. 4.Atoms of some pairs of elements can combine with each other in different, small, whole-number ratios to form different compounds.

Name the acids: HCl HNO HClO H₂SO₄

hydrochloric acid nitric acid chloric acid sulfuric acid

Combustion reactions

involve the rapid combination of a substance with oxygen

A mole

is a means of counting a large number of particles in samples. -One mole is the number of atoms in exactly 12 grams of 12C (carbon-12). -1 mole contains Avogadro's number(6.022 x 10²³ particles/mole) of particles. -Avagadro's number is really, really big!

The law of conservation of mass

is just one of three laws of chemical combination observed, but not understood, by early chemists: - The law of definite proportions states that any given compound is composed of definite proportions, by mass, of its elements. -The law of multiple proportions refers to compounds that are composed of the same elements (CO and CO 2, for example). It states that, for a given mass of one of the elements, the ratio of the masses of any other element in the compounds is a small, whole-number ratio.

Mass number

is the number of protons plus the number of neutrons in an atom.

Decomposition reactions

occur when a single reactant breaks down into less complex products.

Binary ionic compounds form

when metal atoms combine with nonmetal atoms. -Metal atoms give one or more electrons (forming cations) to nonmetal atoms (which form anions). •Compounds are electrically neutral overall Total positive charge = Total negative charge Example: Ca forms only the Ca2+ ionCl forms only the Cl- ion Two Cl- ions are required per Ca2+ to form a neutral compound: CaCl2