Unit 1: Chemistry (P. 134-279)Unit 1: Chemistry (P. 134-279)

Patterns and Compounds– Periodic Table, Naming, Balancing Equations

Chemical Reactions– Energy, 4 Types, Combustion

Acids and Bases– Properties, pH, Reactions

Chemical Reactions in the Environment– Factors affecting Rates, Chemicals and Us

Classification of MatterClassification of Matter

S U S P E N S IO N S E M U L S IO N S C O L L O D IA LD IS P E R S IO N

E L E M E N TS C O M P O U N D

P U R E S U B S TA N C E

S O L U TIO N M E C H A N IC A LM IX TU R E

M IX TU R E

M A TTE R

Classification of MatterClassification of Matter PURE SUBSTANCE:A substance with a fixed composition

and constant properties– ELEMENT: A substance that cannot be broken down into simpler substances

by chemical means. Atoms are the simplest particles that cannot be broken down by chemical means

– COMPOUND: A substance that is made up of two or more different atoms (molecules). These substances can be broken down only by chemical means.

MIXTURE: A mixture consists of two or more kinds of matter, each keeping its own characteristic properties.

– SOLUTIONS: A mixture that is homogeneous. If the solution is a liquid or gas, it is transparent.

– MECHANICAL MIXTURE: A heterogeneous mixture with parts that are visibly distinguishable

MetalsMetals MetalloidsMetalloids NonmetalsNonmetals

Metals vs. Non MetalsMetals vs. Non Metals

•Shiny

•Ductile

•Malleable

•Conducts Electricity

•Conducts Heat

•Dull

•Brittle

•Does Not Conduct Electricity

•Does Not Conduct Heat

Elements and the Periodic Table:Elements and the Periodic Table:A Review A Review

Every Element has a unique– Name– Symbol– Atomic Mass Number (A)

Represents the number of protons + number of neutrons

– Atomic Number (Z) Represents the number of protons and the number of electrons in a

neutral atom

– The number of neutrons can be calculated by subtracting A - Z

Atomic Number Atomic MassAtomic Number Atomic Mass

He2

4

Atomic Number

Atomic Mass

Number of electrons, protons

Number of Protons and Neutrons

Number of Neutrons = Atomic Mass – Atomic Number

ExampleExample

19

K39.098

Name Potassium

Atomic Mass 40

Atomic Number 19

Electrons & Protons

19

Neutrons 20

Grouping of ElementsGrouping of Elements

Elements are subdivided into:– “groups” or "families" (vertical columns)– and “periods” (horizontal rows)

Metals elements are on the left Non-metal elements on the right separated by a dark "staircase line". Elements bordering this division line exhibit some

properties of both metals and non-metals and are called metalloids.

Copy table 5.1 on page 140 into your notes.

Alkali Metals

Alkaline Earth Metals

Group 3

Carbon Group

Nitrogen Group

Oxygen Group

Halogens

Noble Gases

Group NamesGroup Names

Bohr-Rutherford DiagramsBohr-Rutherford Diagrams The following information is required:

– 1. Number of Electrons: Is the same as the number of protons in a neutral atom. The electrons

are organized into shells in the following order.– up to 2 electrons in the first shell– up to 8 electrons in the second shell– up to 18 electrons in the third shell– up to 32 electrons in the fourth shell

– 2. Number of Protons Is the same number as the atomic number

– 3. Number of Neutrons Can be determined by subtracting the atomic mass from the atomic

number

Bohr Rutherford DiagramBohr Rutherford Diagram

18p36n

Nucleus with protons and Neutrons

Electron Orbits (shells) with a 2,8,8, pattern

Predicting Chemical ReactivityPredicting Chemical Reactivity

Elements with 8 electrons in their outer energy level appear to have a special significance. Elements with this arrangement do not react easily and are considered stable.

All noble gases (Neon, Krypton, Xenon, Radon) have 8 electrons in their outer energy level and are very non-reactive elements (Helium is a special gas that is very stable with 2 electrons in its first level).

All elements want to be stable and therefore want to gain or lose electrons in order to achieve a stable 8 configuration (Stable Octet).

Whenever an atom gains or loses electrons they become negative or positive and they are called ions.

Two main factors determine chemical Two main factors determine chemical activity(reactivity)activity(reactivity)

1) The number of electrons in the outer energy level– i) Elements with 1-3 electrons on outer level lose

electrons (become positive)– ii) Elements with 5-7 electrons in outer level gain

electrons (become negative)– iii) Elements with 4 electrons in outer level are special

(tend to become positive) 2) The number of energy levels

– As the number of energy levels increase, the attraction between those electrons in the outermost energy level and the positive nucleus decrease

Ions: To gain or lose an Ions: To gain or lose an ElectronElectron

Positively Charged: Cations– When a neutral atom gives up one or more electrons,

the positively charged ion that results is called a Cation.

– For example:

Negatively Charged: Anions– When a neutral atom gains one or more electrons, the

negatively charged ion that results is called an Anion.– For example:

Electron Dot DiagramsElectron Dot Diagrams

A Bohr-Rutherford diagram represents an atom and all its electrons.

A simpler way to represent atoms and ions of atom is with electron dot diagrams

Electron Dot Diagrams show only the outer energy level (valence shell) of an atom. Only these electrons are represented because they are responsible for an atom’s chemical properties. For example:

Lewis Dot / Electron Dot Lewis Dot / Electron Dot diagramsdiagrams

C N

Chemical Bonds: Forming Chemical Bonds: Forming CompoundsCompounds

Most substances on earth do not exist as elements, they are composed of two or more different elements joined together to make compounds.

When two atoms collide, valence electrons on each atom interact. A chemical bond forms between them if the new arrangement of their valence electrons have less energy than their previous arrangement.

For many atoms that new arrangement of their electrons will be that of their closest noble gas.

Atoms may acquire a valence shell like that of its closest noble gas in one of three ways:

– 1. An atom may give up electrons and forma ion– 2. An atom may gain electrons and form an ion– 3. An atom may share electrons

Ionic CompoundsIonic Compounds

Substances held together by ionic bonds are called Ionic compounds e.g. NaCl, KCl. Ionic Bonds occur because of the attraction of cations and anion for each other. Electrons are transferred between the atoms during bond formation.

Properties include:

• High melting point (i.e. strong bonds)

• Conduct electricity when dissolved in water or molten• Form crystal lattice structures• Soluble in water

Molecular Compounds Molecular Compounds

Substances that are composed of molecules are called molecular compounds. Many non-metals form compounds with other non-metals. When this occurs there is no transfer of electrons between the two atoms instead they share electrons forming a covalent bond.

Although bond between atoms are strong, bonds between molecules are weak. eg. Moth crystals, nitrogen gas etc.

Properties Include: Low melting and boiling points Often have an odour Don’t conduct heat Don’t conduct electricity (non-electrolytes)

Diatomic molecules (e.g. O2, F2 etc.) are also the result of covalent bonds.

Chemical Naming and FormulasChemical Naming and Formulas

Binary IonicTransition Metals

– Stock versus Classical

Polyatomic IonsBinary Molecular

General RulesGeneral Rules

The Metal is always written firstThe nonmetal suffix in a compound is either

“ide” or “ate”Every compound must be electrically

neutral– All Positive charges must equal Negative

charges

Binary Compounds: Formula to NameBinary Compounds: Formula to Name

Composed of two ElementsOne metal and one nonmetalWrite the name of the metal first unchangedWrite the name of the nonmetal secondChange the ending to an “ide”

– LiCl Lithium Chloride

– MgI2 Magnesium iodide

Binary Compounds: Name to FormulaBinary Compounds: Name to Formula

Write the symbol for each element with the metal written first

Find the ionic charge for each element Cross the number value of the charge and place it

as the subscript of the other element Reduce the values to lowest ratio

Magnesium Oxide Mg2+ O2-

Mg2O2

MgO

Transition Metals: Groups 3-12+Transition Metals: Groups 3-12+Name to formulaName to formula

Almost all are able to form more than one cation

When writing the formula the charge of the metal cation will be indicated by roman numerals after the metal

Lead (III) chloride PbCl3

Iron (II) oxide FeO

Transition Metals: Groups 3-12+Transition Metals: Groups 3-12+Formula to NameFormula to Name

Finding the charge on the metal can be done two ways

1. Reverse Cross-Over Method– The subscript of the nonmetal becomes the charge of

the metal– Sometimes the charge is misleading

2. Charge Balancing– Charge = Subcript of the nonmetal multiplied by the

charge of the nonmetal divided by the subscript of the metal

Chemical Equations and ReactionsChemical Equations and ReactionsA chemical equation is a description of a chemical reaction using chemical symbols, not wordsSteps:1) The reactants are written first2) The products are written second3) The state for each atom is indicated

(g) gas, (s) solid, (l) liquid, (aq) aqueous

4) The reactants and products are separated by an "arrow" ( )

e.g. Word Equation

Hydrogen gas plus chlorine gas produces hydrogen chlorine gas

e.g. Chemical Equation

H2(g) + Cl2(g) HCl(g)

Balanced and Unbalanced Chemical Balanced and Unbalanced Chemical Equations Equations

The Law of Conservation of Mass states:

Matter cannot be created or destroyed; it can only be changed from one form to another.

Therefore, the number of atoms in the reactants must equal the number of atoms in the products

An unbalanced or skeleton equation does not follow the Law of Conservation of Mass. The number of atoms on the left side (reactants) does not equal the atoms on the right side (products)

e.g. H2(g) + Cl2(g) HCl(g) 4 atoms (2 H, 2 Cl) 2 atoms(1 H, 1 Cl)

A balanced chemical equation follows the Law

of Conservation of Mass. The number of atoms

on the left side (reactants) equals the atoms on

the right side (products)

e.g. 1H2(g) + 1Cl2(g) 2HCl(g)

4 atoms (2 H, 2 Cl) 4 atoms(2 H, 2 Cl)

Writing Balanced Chemical EquationsWriting Balanced Chemical Equations

1. Write the chemical formula for each reactant and product followed by the state of each: solid (s); liquid (l); gas (g); aqueous(aq)

2. Adjust the numbers of molecules until there are the same number of atoms of each type on both sides of the equation. This balances the mass of both the reactants and products.

3. Usually, balancing is easiest when hydrogen and oxygen atoms are left until the end

NOTE: Do not change the subscript in a formula to balance an equation. Changing these numbers changes the molecular structure of the molecule.

Energy Changes and Chemical Energy Changes and Chemical ReactionsReactions

Chemical reactions, physical changes of state and dissolving processes often involve energy changes.

Exothermic Processes:

Processes that release energy (e.g. heat and light) and increase the temperature of the surroundings.

Endothermic Processes:

Processes that absorb energy and decrease the temperature of the surroundings.

Factors Affecting Chemical Reaction Factors Affecting Chemical Reaction RateRate

The Rate of Reaction is defined as:

The time it takes for a given product to form, or for given amounts of reactant to react.

Reaction rate is determined by:i. Measuring how fast reactants are used up.ii. Measuring how fast the products are formed.

Factors affecting Reaction Rate

1. Concentration and Reaction Rate

Concentration (amount of substance in a given volume) Rate

2. Surface Area and Reaction Rate

Surface Area (area exposed) Rate

3. Temperature and Reaction rate

Temperature Rate

4. Catalysts and Reaction Rates

A Catalyst is defined as:

A substance that speeds up the rate of a chemical reaction without being used up in the reaction.

Catalyst lower the energy required to break the bonds that hold substances together. Examples include: enzymes (biological catalysts), platinum, rhodium and palladium (chemical catalyst used in catalytic converters)

Types of Chemical ReactionsTypes of Chemical ReactionsThere are four basic patterns that most chemical reactions follow:

1) Synthesis ReactionsThis type of reaction fits the general pattern:

A + B AB

e.g. N2(g) + 3H2(g) 2NH3(g)

CaO(s) + H2O(l) Ca(OH)2

A synthesis reaction involves the formation of a new compound from simpler elements or compounds

Combustion reactions (involving the reaction

with O2) are examples of Synthesis Reactions

e.g. Cu(s) + O2(g) 2CuO(s)

Mg(s) + O2(g) 2MgO(s)

2) Decomposition Reactions2) Decomposition Reactions

These type of reactions are opposite to direct combinations. They fit the general pattern:

AB A + B

e.g. CuCO3(s) CuO(s) + CO2(g)

2KClO(s) 2KCl(s) + 3O2(g)

A decomposition reaction involves the breaking down of a compound into simpler compounds or elements

3) Single Displacement Reactions3) Single Displacement ReactionsA single displacement or substitution reaction fits the general pattern of:

A + BC AC + B

This type of reaction involves a change in partners. One element displaces or knocks off another element in a compound..

e.g. Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g)

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

4) Double Displacement Reactions4) Double Displacement ReactionsA double displacement reaction fits the following general pattern:

AB + CD AD + CB

This type of reaction involves a change of both partners. The cation (positive element or polyatomic ion) of one compound changes place with the cation of the second compound.

e.g. Na2S(aq) + ZnCl2 (aq) ZnS(s) + 2NaCl(aq)

AgNO3(aq) + KBr(aq) AgBr(s) + KNO3(aq)

SF4(s) + 2H2O(l) SO2(g) + 4HF(aq)

Carbon Chemistry

Organic Chemistry: The study of carbon containing compounds and their properties e.g. hydrocarbons

When hydrocarbons (contain carbon and hydrogen) are burned in enough oxygen complete combustion occurs.

Hydrocarbon + oxygen gas carbon dioxide + water + E (good supply)

If hydrocarbons are burned in a poor supply of oxygen, incomplete combustion occurs.

Hydrocarbon + oxygen gas carbon dioxide + water + E (poor supply) + carbon monoxide + residue

Classification of Substances by Their Classification of Substances by Their BehaviourBehaviour

The process of grouping substances

according to common properties is called

classification.

Previously we have classified substances

according to:

i) State (e.g. solid, liquid or gas)

ii) Composition (e.g. pure substances, mixtures etc.)

Matter can also be classified by

chemical behaviour.

Acids and bases make up two classes of

compounds that have been classified by

their chemical behaviour.

Acids and BasesAcids and BasesAcids:

An acid is a compound that dissolves in water to produce hydrogen ions (H +) in solution. e.g. HCl

Bases:A base is a compound that dissolves in water to produce hydroxide ions in solution (OH -) e.g. NaOH

Copy Table 7.3 “Acids and Bases: A Summary” found on page 230 in your text.

Preparation of Common AcidsPreparation of Common AcidsA common way to prepare an acid is to react a nonmetal oxide

with water. An oxide is an element combined with only

oxygen e.g.

sulphur trioxide + water sulphuric acid

carbon dioxide + water carbonic acid

Some common acids in the laboratory include:

i) sulfuric acid ( H2S04 )

ii) nitric acid (HNO3)

iii) hydrochloric acid (HCl)

iv) acetic acid, (CH3COOH)

Other common acids include:

i) acetylsalicylic acid (aspirin)

ii) ascorbic acid (vitamin C)

iii) carbonic acid (carbonated soft drinks)

Preparation of Common BasesPreparation of Common Bases

A common way to prepare a base is to react a metal oxide

with water. e.g.

sodium oxide + water sodium hydroxide

calcium oxide + water calcium hydroxide

Some common bases in the laboratory include:

i) Sodium hydroxide (NaOH)

ii) Calcium hydroxide (Ca(OH)2)iii) Potassium hydroxide (KOH)

iv) Magnesium hydroxide (Mg(OH)2)

IndicatorsIndicatorsAn indicator is a chemical that changes colour as the concentration of H+ (aq) and OH- (aq)

changes. e.g.

i) Litmus: • blue litmus turns red in acid• red litmus turns blue in base

ii) Phenolphthalein • turns pink in base

Indicators can be made from flowers, fruits, vegetables, leaves (e.g red cabbage, tea etc.)

Synthetic Indicators are more easy to use than natural indicators because they: • last longer than natural indicators • can be produced in large quantitiese.g. bromothymol blue (BTB)

phenolphthalein methyl orange methylene blue

The pH ScaleThe pH ScaleThe pH scale describes the "strength of the hydrogen ion (H+)".

The scale is numbered from 0 to 14• acids have a pH less than 7 [H+] > [OH-]• bases have a pH more than 7 [H+] < [OH-]• neutral substances have a pH of 7 [H+]= [OH-]

The change in 1 pH unit represents a tenfold increase in the concentration of hydrogen ions in solution. e.g.

A pH of 2 is 10 x's stronger than a pH of 3A pH of 2 is stronger than a pH of 5A pH of 2 is _ stronger than a pH of 7

pH can be estimated using pH paper or measured using a pH meter (measures electric properties)

The Strength Of Acids And BasesThe Strength Of Acids And BasesThe strength of an acid or base is dependant on two factors:

1. Concentration

The concentration of an acid or base is the amount of the pure substance dissolved in 1 L of water.

2. Ionization

When acids and bases are dissolved in water, they ionize (break apart into charged particles). The term “Percent Ionization” refers to the number of molecules that will ionize for every 100 molecules

that dissolve. e.g. HCl + H2O H3O+ + Cl-

Solutions that form ions in water are called electrolytes. Electrolytes conduct electricity.

The higher the concentration of ions the stronger the electrolyte.

The Strength of Acids

Strong acids: ionize completely in water e.g H2SO4

Weak acids: ionize partially in water e.g. CH3COOH

The Strength of Bases

Strong Bases: ionize completely in water e.g NaOH

Weak Bases: ionize partially in water e.g. NH3

NeutralizationNeutralization

Neutralization occurs when hydroxide ions (base) and hydrogen ions (acid) are mixed to make water. The general word equation is:

Acid + Base Water + Salt

e.g

hydrochloric + sodium water + sodium chloride acid hydroxide

(HCl) (aq) + ( NaOH)(aq) ( H2O)(l) + ( NaCl) (aq)

After neutralization, the solution no longer has a high concentration of either ion.

Soaps and Detergents Soaps and Detergents What makes up soap ?

1. fatty acid (lipid)2. strong base (NaOH)

The word equation is: fat + base soap + glycerol

Soap curds cling as scum to whatever it comes into contact with, and does not rinse away easily. This problem led to the development of synthetic detergents called syndets. Advantages include:

1. good at removing dirt2. more soluble in water3. prevented dirt from collecting back onto clothes4. did not form a curd5. mild to hands and fine fabrics6. less expensive (made from plant oils and animal fats)

How soap cleans

A soap or detergent molecule consists of two ends:1. Hydrophillic (water loving)

The end with the sodium ion is attracted to water and becomes soluble

2. Hydrophobic (water hating) Hydrocarbon end is attracted to insoluble dirt (grease)

on clothes etc.

For example: