CHEMISTRY 161

Chapter 2

Compounds and Chemical Reactions

1. Structure of an Atom

subatomic particles

electrons(‘cloud’)

protons(nucleus)

neutrons(nucleus)

m(n) / m(e) ≈ 2000 m(n) > m(p)

2. Atomic & Mass Number

AZ Xatomic number

(number of protons)

(number of electrons)

mass number

(number of protons plus neutrons)

Compounds & Chemical Reactions

1. Compounds

2. The Chemical Formula

3. The Chemical Equation

4. Energy in Chemical Reactions

5. The Name of Chemicals

1. Compounds

molecular compounds ionic compoundsEXP1

Molecular Compounds

1. consist of electrically neutral particles called molecules

2. each molecule consists of atoms

3. atoms are connected via electrons

4. connections are called bonds(‘springs’)

EXP2

Molecular Compounds

Group Period IVA VA VIA VIIA Noble Gas 2 CH4 NH3 H2O HF Ne 3 SiH4 PH3 H2S HCl Ar 4 GeH4 AsH3 H2Se HBr Kr 5 SbH3 H2Te HI Xe

lots of molecules contain hydrogen

EXP3

H2, He

Jupiter

PH3

CH4

EXP4

H2, He

Saturn

NH3/PH3

CH4

H2O (s)

atom(neutral)

add electron(s)

(reduction)

anion(Cl-)(negative charge)

take electron(s)

(oxidation)

cation(Na+)(positive charge)

Ionic Compounds I1. consist of charged particles

2. charged particles are called ions

3. ions are formed by electron transfers from atoms

Ionic Compounds II

4. ionic compounds are held together by electrostatic forces

Cl-Na+metal non-metal

NaCl MgO EXP5

2. The Chemical Formulacollection of chemical symbols used to describe

the composition of elements and compounds

HeEXP6

F F

F2

O2

O O

S8

N2

N N

P4

H2

H H

2. The Chemical Formulacollection of chemical symbols used to describe

the composition of elements and compounds

NaCl

H2O Fe2O3

CaSO4 2 H2O

Compounds & Chemical Reactions

1. Compounds

2. The Chemical Formula

3. The Chemical Equation

4. Energy in Chemical Reactions

5. The Name of Chemicals

3. The Chemical Equation

chemical equation describes what happens in a chemical reaction

chemical reaction is combination of elements and/or compounds

H2 + O2 H2O

balancing & mass conservation

2 2

3. The Chemical Equation

2 H2 + O2 2 H2O

s = solid l = liquid g = gas aq = aqueous solution

2 H2(g) + O2 (g) 2 H2O (l)

1.phosphor with oxygen

2. sulfur with oxygen

Examples

3. methane with oxygen EXP7

Compounds & Chemical Reactions

1. Compounds

2. The Chemical Formula

3. The Chemical Equation

4. Energy in Chemical Reactions

5. The Name of Chemicals

4. Energy in Chemical Reactions

a chemical reaction either absorbs or releases

energy(heat or light)

releasing energy (heat) exothermic

absorb energy (heat) endothermic

EXP1/2

CONSERVATION OF ENERGY

KINETIC ENERGY

POTENTIAL ENERGY

energy of an object due to its motion

Ekin = ½ m v2

energy of an object due to its position

Epot = m g h

Etotal = Epot + Ekin = constant

chemical energy is a form of potential energy

EXP3

Compounds & Chemical Reactions

1. Compounds

2. The Chemical Formula

3. The Chemical Equation

4. Energy in Chemical Reactions

5. The Name of Chemicals

Organic Compoundscompounds containing mostly hydrogen and carbon

minor amount other elements (N, O, S, P…)

hydrocarbons

H C

alkanes CnH2n+2

CO2

CO H2O

H2COC4H10

Organic Compounds?

C4H10 combustion

EXP4

Titan – Saturn’s Largest Moon

Cassini-Huygens Mission

Cassini-Huygens Mission

Inorganic Compounds

binary compounds

compounds consisting of ONLY TWO different elements

NaCl CO2 CaSO4

nomenclature naming compounds

nomen (Latin) = name

symbol stem first element second element O ox- oxygen oxide S sulf- sulfur sulfide N nitr- nitrogen nitride P phosph- phosphorus phosphide F fluor- fluorine fluoride Cl chlor- chlorine chloride Br brom- bromine bromide I iod- iodine iodide

part one (metal)

part two

English name ofelement

stem + ide

NaCl MgO BeS

Metal (Main Group) + Non-Metal

ionic compounds

(metal + non-metal)

stem + ide

Nomenclature Inorganic Compoundsmain group

metal metal +

Greek Prefixes mono- = 1 (often omitted) hexa- = 6 di- = 2 hepta- = 7 tri- = 3 octa- = 8 tetra- = 4 nona- = 9 penta- = 5 deca- = 10

PF3 PF5

CO CO2

HCl

NO NO2N2O5

Molecular Compounds

ionic compounds

(metal + non-metal)

stem + ide

Nomenclature Inorganic Compoundsmain group

metal element +

molecular compounds prefix + element + prefix + stem + ide

ionic compounds

(metal + non-metal)

stem + ide

Nomenclature Inorganic Compoundsmain group

metal

trans. group

metal

element +

molecular compounds prefix + element + prefix + stem + ide

ionic compounds

cations & anions

Mn+ Em-

metalstransition metals

nonmetals

compounds must be electrically neutral

charge state of ions

-/+3/5 -2 -1 0+1 +2 +3

-/+2/4

K2S CaCl2

main group metals – always start with cation

Chromium Cr2+, Cr3+ Zinc Zn2+ Manganese Mn2+, Mn3+ Silver Ag+ Iron Fe2+, Fe3+ Cadmium Cd2+

Cobalt Co2+, Co3+ Gold Au+, Au3+ Nickel Ni2+ Mercury Hg2

2+, Hg2+ Copper Cu+, Cu2+

NiCl2 CuO CuCl

transition metals – always start with anions

include oxidation state in name – no prefixes

Mn2O3 B2O3

ionic compounds

(metal + non-metal)

stem + ide

Nomenclature Inorganic Compoundsmain group

metal

trans. group

metal

element +

molecular compounds prefix + element + prefix + stem + ide

stem + idemetal + oxstate +

molecular compounds

ionic compounds

polyatomic ionic compounds

ion name ion name NH4

+ ammonium ion CO32- carbonate ion

OH- hydroxide ion H3O+ hydronium ion NO2

- nitrite ion SO32- sulfite ion

NO3- nitrate ion SO4

2- sulfate ion ClO2

- chlorite ion CrO42- chromate ion

ClO3- chlorate ion Cr2O7

2- dichromate ion PO4

3- phosphate ion

ammonium chloride sodium dichromate magnesium carbonate

rubidium sulfate calcium phosphate

molecular & ionic compoundsproperties

melting pointmolecular compounds – weak interactions (gases, liquids) – low melting point

ionic compounds – strong interactions (solids) – high melting point

electrical conductivity

molecular – do not conduct electricity in solid or liquid state

ionic – do not conduct electricity in solid state

ionic – conduct electricity in liquid and aqueous state

Compounds & Chemical Reactions

1. Compounds

2. The Chemical Formula

3. The Chemical Equation

4. Energy in Chemical Reactions

5. The Name of Chemicals