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UNIT 1Chemistry in

ActionThis unit provides you with the opportunity to examine the

interactions among elements as they form compounds through chemical reactions. You will become familiar with the formulas and

naming of binary compounds, and investigate the Law of Conservation of Mass. The recognition that mass is conserved in

chemical reactions allows you to balance equations with both words and symbols, and classify them by type. The principles of

acid-base chemistry are studied and extended to large-scale environmental interactions. You will investigate the use of chemistry in biological, industrial, and domestic settings,

recognizing that chemical use is pervasive in modern society.

Specific Learning Outcomes Relate an element’s position on the periodic table to its combining capacity

(valence). Include: alkali metals, alkaline earths, chalcogens, halogens, noble gases.

Explain, using the periodic table, how and why elements combine in specific ratios to form compounds. Include: ionic bonds, covalent bonds.

Write formulas and names of binary ionic compounds. Include: IUPAC guidelines and rationale for their use.

Write formulas and names for covalent compounds using prefixes. Include: mono, di, tri, tetra.

Investigate the Law of Conservation of Mass, and recognize that mass is conserved in chemical reactions.

Balance chemical equations.

Investigate and classify chemical reactions as synthesis, decomposition, single displacement, double displacement, or combustion.

Perform an experiment to classify acids and bases using their characteristic properties. Include: pH, indicators, reactivity with metals.

Explain how acids and bases interact to form a salt and water in the process of neutralization.

Gr. 10 Science Chemistry in Action

Review of the AtomAtoms can be broken down into _______________________________________. The three main subatomic particles are ____________________, ____________, and ______________________.

Charge Location MassProtonsElectronsNeutrons

Determining the Number of Subatomic ParticlesNumber of protonsThe number of protons is equal to the atomic number.

Number of electronsIn any atom, the number of electrons is equal to the atomic number.

Number of neutronsThe number of neutrons is equal to the mass number (rounded to a whole number) minus the atomic number.

Bohr’s Atomic ModelBohr's model of the atom proposed that electrons occupy __________________ or ________________________ or _________________. Bohr discovered that the location


Mass number = atomic number (number of protons) + number of neutrons

Atomic number = mass number- number neutrons

Protons =

Electrons =

Neutrons =

=

of each shell was a certain distance from the nucleus. He also discovered that only a specific number of ________________________ populated each shell.

When electrons occupy the shells, they begin at the_____________________ shell to the nucleus. The first shell can contain a maximum of _______ electrons, and the second and third shells allow a maximum of __________ electrons.

Hydrogen Helium

Bohr’s Atomic ModelLithium


Fluorine

These electrons are important in helping to determine how an element will react with other materials. These electrons in the outermost energy level are called ________________________________________.

The Periodic TableDmitri Mendeleev, a Russian scientist and professor, placed characteristic properties of elements on pieces of paper and arranged them in many different ways. He discovered a certain pattern or repetition of properties.

This repetition of properties or _________________ was an important outcome of Mendeleev's work. Mendeleev used the periodicity of properties to create a


When an element has more than four electrons in its shell, you arrange the dots in twos.

periodic table. This table summarized the structure and properties of the elements.

Today's periodic law states that ______________________________________ _______________________________________________________________.

The periodic table is an important tool for chemists. It quickly determines some key facts about an element. The basic information with regard to the structure of an atom is quickly established with the periodic table.


The Periodic TableColumns in the Periodic TableThe periodic table arranges the elements in columns. A single column is called a __________________ or ____________________. A family contains elements that have similar but not identical properties.

Alkali Metals ( ) o Occupies the _______ column in the periodic table. o Has _______ valence electron in its outer energy level. o Most reactive metals o In their natural state, alkali metals are always found combined with other

substances because of their reactivity.

Alkaline Earth Metals ( )o Located in the ________________ column of the periodic table. o Less reactive than the alkaline metal family. o Has _______ valence electrons in the outer energy level.

Chalcogens ( ) o Located in the __________ column.o Slightly less reactive than the halogen family. o Have _________ valence electrons in their outer energy level

Halogens ( ) o The halogen family is the __________ family o Halogens such as fluorine and chlorine react with one atom of hydrogen to

form HF and HCl respectively. o Have ________ valence electrons o Most reactive non-metals.o In their natural state, the highly reactive halogens are found combined with

another element.

Noble Gases ( ) o The noble gas family is the 18th familyo Called noble gases because they do not generally form compounds with

other elements. o Inert, unreactive because their outer energy levels are completely filled with

electrons. o No natural compounds formed from these gases exist.

The Periodic TableHydrogeno Sometimes hydrogen behaves as a _________ and sometimes as a

___________.


o Hydrogen has _______ electron in its outermost energy level, so it is reactive.o Almost all the hydrogen on Earth is combined with other materials or with

itself.

Look at your periodic table and note the number of valence electrons in each family. State the number of valence electrons for the families in the table shown below.

Family Number ofValence Electrons

alkali metals

alkaline earth metals

chalcogens

halogens

noble gases

Rows in the Periodic TableRows in the periodic table are called _______________. Elements in periods do not demonstrate similar properties as they do in families. Periods, however, show trends.


You should be able to predict with some accuracy the properties of elements that are in the same families.

Electron Dot DiagramsAn electron dot diagram or Lewis diagram represent an _______________and its _____________________. The electrons in the valence shell are shown as __________ placed around the symbol. Electron dot diagrams are a valuable tool for _______________, _______________, and _______________compound formation.

Example:Draw an electron dot diagram for calcium.

Example:Draw an electron dot diagram for sulphur.

Example:Draw an electron dot diagram for nitrogen.


Ionic BondsIonic bonds result when electrons are transferred from metal atoms to non-metal atoms. The metal atoms lose electrons to become positive ions, while the non-metal atoms gain electrons to become negative ions. The ions are then held together by the action of opposite charges in an ionic bond.

Atoms are considered neutral because the number of protons in the nucleus and the number of electrons in the shells around the nucleus are ____________________, resulting in a ____________ net charge for the atom.

Cations (Positive Ions)What happens if an electron is removed from an atom?

Sodium atom Sodium ion

How many positive charges in the atom?

How many positive charges in the ion?

How many negative charges in the atom?

How many negative charges in the ion?

What is the residual (net) charge in the atom?

What is the residual (net) charge in the ion?

Ionic BondsGr. 10 Science Chemistry in Action

Na

Mg

When an atom from the alkali family reacts with an atom from another element, it will ______________________ its valence electron to the other atom. In giving away its electron, the alkali metal atom has a filled outer shell. Also, in giving away its electron, the atom becomes positively charged with a __________________.

Atoms from the alkaline earth family have two valence electrons. These atoms will give off the two valence electrons when combining with an atom from another element. After giving away the two valence electrons, the alkaline earth metal atom has a ______________________.

Alkali and alkaline earth metals form positive ions when forming an ionic bond with another element.

Ionic BondsAnions (Negative Ions)


Always write the charge with the number first, followed by the sign ie.) 1+

8 p8 n

9 p10 n

The oxygen family and the halogen family behave differently. These two families readily _________________ electrons to fill their valence shells so that their electron configuration also resembles a _________________________. The halogens need only one electron to fill their valence shells, so they accept only one electron. Once the extra electron is accepted, a 1- ion is formed.

Oxygen

Oxygen has a combining capacity of two. The chalcogen family all have the same combining capacity.

Fluorine

Fluorine has a combining capacity of one. The halogen family all have the same combining capacity.

Ionic BondsWhen a positively charged ion comes near a negatively charged ion, they _________ each other and form a bond called an ________________________. An ionic bond will hold the two ions together to form a _______________________.

The formation of ___________________ often takes place vigorously when metals and non-metals are placed together. If a sample of sodium metal is placed in a container of chlorine gas, an explosive reaction takes place and the sodium combines with the chlorine to form sodium chloride. The Bohr model below provides an explanation for this reaction.


11 p12 n 17 p

18 n

11 p12 n 17 p

18 n

Notice that atoms when combine to form ionic compounds, they always gain or lose enough electrons to have a valence shell like its closest noble gas neighbour.

Ionic BondsMetals and Non-metals

Metals Non-metals


There are exceptions to this general classification and some families have members that behave as both metals and non-metals (e.g., silicon). These elements are called __________________________. Many periodic tables have stair steps across families at the right side. These steps show the dividing line between metals and non-metals. The elements on the dividing line are metalloids.

Ionic Bonds

State Appearance

Conductivity

Malleability and

Ductility


Metals

Non-metals

Metalloids


Ionic BondsReview of Valence Electrons

Family Valence Electrons

Electrons Lost/Gained

Chargeof Ions

Alkaline metals

Alkaline earth metalsBoron

Carbon

Nitrogen

Chalcogen

Halogen

Noble gas

When ionic compounds are formed, elements with a positive valence number will combine with elements having a negative valence number.

In general, ______________________ (families 1 and 2) combine with ____________________________ (families 16 and 17).


Covalent BondsMany compounds do not form ionic bonds. These compounds contain two or more non-metallic atoms. For example, C02 is made of two different non-metals, carbon and oxygen. These compounds are formed through the _______________________ of valence electrons. A covalent bond is formed when two or more non-metallic atoms share valence electrons.

Two hydrogen atoms form a covalent bond by sharing electrons to produce a hydrogen molecule.

o A molecule is the smallest unit of a covalent compound.o A molecule has different characteristic properties from the atoms that

form it.

The Bohr model for hydrogen shown below illustrates a covalent bond.

The electrons are shared in the outer shells of both atoms. This covalent bond forms a molecule of hydrogen (H2). The two hydrogen atoms form a __________________ molecule.

Example:H2O

Covalent BondsDiatomic Molecules


A basic rule in chemistry is that an atom with eight electrons in its outer shell is particularly stable. This need for eight electrons in a covalent bond is called the

octet rule.

Name of Element

Symbol for One Atom of the

Element

Formula for One

MoleculeHydrogen

Nitrogen

Oxygen

Fluorine

Chlorine

Bromine

Iodine

The elements forming diatomic gases are unstable as single atoms and combine almost instantaneously to form stable molecules.

Diatomic molecules are still classified as elements even though they are molecules. Remember that diatomic molecules are made of only one kind of atom.


Chemical FormulasChemistry has its own language. Chemists communicate in this language to describe the millions of known compounds. This communication depends on a standard system of naming and writing the formulas for compounds. Chemists formed a group to standardize the system of naming and called themselves the International Union of Physical and Applied Chemists, or ________________________.

A chemical formula is a shorthand method to represent compounds that uses the elements' symbols and subscripts. The chemical formula gives the following information:

o The different elements in the compound.o The number of atoms of each element in the compound.

Example:

H2O

Na2SO4


______________________ tells you the amount of each element.

______________________ contains:

______________________

______________________

*No subscript indicates no ________________ is present.

Contains:

______________________

______________________

______________________

Naming Ionic CompoundsWhen naming an ionic compound from its formula follow the rules below:

1. The cation (positive ion) is named first, followed by the anion (negative ion).

2. Write the full name of the metallic element (positive ion). 3. Write the name of the non-metallic element (negative ion) and change

the ending to "-ide".

Example: Write the name of NaCl.

Step 1: Name the first element.

Step 2: Name the second element and change the ending to "-ide".

The name of the compound is _________________________________________.

Example: Write the name of Mg3P2.

Step 1: Name the first element.

Step 2: Name the root of the second element and add "-ide".

The name of the compound is _________________________________________.

Writing Ionic FormulasThe following must occur, when writing the formula for ionic compounds.

1. The formula must have the cation first, followed by the anion.


2. The sum of the charges of the ions must be zero. That is, the number of positive charges must equal the number of negative charges.

3. You may not change the charge of the ions to make the ion charges equal zero.

The "Cross-Over" Method1. Write the ions and their charges side by side. 2. Make the number of the charge of one ion the subscript of the other ion

(omitting the + or – sign). Remember we do not write the number one as a subscript.

3. Reduce all subscripts to their simplest form, if necessary.

Example: Write the formula for aluminum oxide.

Step 1: Write the ions and their charges.

Step 2: Make the number of the charge of one ion the subscript of the other ion.

Example:Write the formula for barium fluoride.

Writing Ionic FormulasExample:Write the formula for magnesium chloride.


The charge on the fluoride ion is 1-. Since IUPAC rules do not write the number one as a subscript, we leave the barium without a subscript.

Example:Write the formula for calcium oxide.


Polyatomic IonsSome ions are composed of several atoms joined covalently. These are called polyatomic ions (poly = many).

The charge for polyatomic ions is for the whole group of atoms not just for the atom written last. DO NOT change the subscripts of polyatomic ions; if you change the subscripts you change the identity of these ions.

When indicating the presence of more than one polyatomic ion in a compound, we use parenthesis around the polyatomic ion, followed by its subscript. For example, the compound Al(CH3COO)3 has an aluminum ion and 3 acetate ions. Placing the acetate ion in parenthesis and following it with the subscript 3 indicates there are 3 acetate ions.

Example:Write the name for KNO3.

Step 1: Identify the cation.

Step 2: Identify the anion.

Step 3: Write the name of the cation first, followed by the anion.

Example:Write the name of Na3PO4.





Polyatomic IonsWriting the formula for polyatomic ions is the same as writing the formula for ionic compounds. You will use the cross-over method and your polyatomic table.

Example:Write the formula for sodium sulfate.




Example: Write the name of ammonium thiocyanate.


Stock Naming SystemMost of the transition metals have more than one possible ion charge. They are often referred to as being _______________. For example,

Ion PossibleIon Charges

Copper 1+, 2+Iron 2+, 3+

Cobalt 2+, 3+Chromium 2+, 3+

Lead 2+, 4+Tin 2+, 4+

o In 1919, Alfred Stock (1876 – 1946), a German chemist, suggested using numbers to indicate the charge of the ions. Prior to this the ions were given different names based upon their charge.

o The Cu+ ion was called cuprous and the Cu2+ ion was called cupric. However, the Fe2+ ion was ferrous and the Fe3+ ion was ferric.

o Since the charges were not always the same, the "–ic" and "–ous" suffixes caused some confusion.

o Today, the Stock naming system uses Roman numerals following the ___________ ion's name to indicate the ion's charge.

Example:

Copper (I) = Cu+ Copper (II) = Cu2+

Iron (II) = Fe2+ Iron (III) = Fe3+

Multivalent CompoundsExample: Write the formula for iron (III) chloride

Step 1: Write out the ions.


As a general rule, all metals are multivalent (have more than one ion charge) except group one and two metals, silver, cadmium, zinc,

and aluminum. Unless the metal is one of these use the Roman numeral.

Step 2: Cross-over the charges.

Example: Write the formula for lead (IV) sulfide.

Step 1: Write the ions.

Step 2: Cross-over the charges.

Step 3: Reduce the subscripts.

Naming Multivalent CompoundsWe name in a very similar manner as those ions with a single ion charge, except we must determine the charge on the metal ion.

Example:Write the name for FeCl3.

Step 1: Use the reverse of the cross-over method and add the charge signs to each ion.


Step 2: Check that the charge of the anion is correct. If not, multiply both charges by the multiplier needed to have the correct charge of the anion.

Step 3: Write the name, indicating the charge of iron using roman numerals.

Example:Write the name for FeO.

Step 1: Use the reverse of the cross-over method and add the charge signs to each ion.

Step 2: Check that the charge of the anion is correct. If not, multiply both charges by the multiplier needed to have the correct charge of the anion.

Step 3: Write the name.


Naming Multivalent CompoundsExample:Write the name for MnO2.

Example:Write the name for PbO.


Naming Covalent CompoundsNon-metals tend to combine chemically by sharing electron pairs. These bonds are known as ____________________________________. Neutral compounds made of atoms joined covalently are called ____________________ or _____________ _________________________.

We name covalent compounds differently than ionic compounds. We must indicate the number of each element by adding a prefix in front of the element's name.

Subscript Prefixonetwo

threefourfivesix

seveneightnineten

There are three exceptions to the naming rules. Here the common names for the compounds are used:


H2O = waterNH3 = ammoniaCH4 = methane

Naming Covalent CompoundsExample:Write the name for CO2.

Step 1: Name the first atom with prefixes.

Step 2: Name the second element using prefixes and end in "-ide".

Step 3: Write the name of the compound writing the substance found more to the

left on the periodic table first.

Example:Write the name for N2O4.

Example:Write the name for SF6.


Writing Covalent FormulasWriting formulas for covalent compounds involves the following rules:

1. Write the symbol for the first element followed by the subscript indicated by the prefix.

2. Write the symbol of the second element followed by the subscript indicated by its prefix.

DO NOT REDUCE THE SUBSCRIPTS!!!

Example:Write the formula for dinitrogen monoxide.

Step 1: Write the symbol and subscript for the first element.

Step 2: Write the symbol and subscript for the second element.

Step 3: Combine

Example:Write the formula for sulphur hexachloride.

Example:Write the formula for carbon tetrachloride.


Balanced EquationsBalancing EquationsThe Law of Conservation of Mass tells us that every chemical equation must have equal numbers of atoms of each element on each side of the equation.

This means atoms cannot be created or destroyed in a chemical reaction.

As you balance equations, there are several rules to remember.

1. You cannot change the formula of any reactant or product to change the numbers of atoms.

2. You can only change the coefficients in front of the reactants and products.

a. Coefficients can be placed only in front of the formula, not somewhere inside it.

b. Coefficients apply to the whole molecule. If no coefficient is shown in front of a molecule, it means the molecule has a coefficient of 1.

c. Note the difference between a coefficient and a subscript. i. A ___________________________ tells us the number of molecules

in an equation and can be changed to balance an equation.

ii. A ___________________________ tells us the number of atoms in a molecule and cannot be changed.


Balanced EquationsThere are some rules that you can use when you are given an unbalanced equation that needs to be balanced.

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

1. Determine the number of atoms for each element in the molecules for reactants and products.

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

2. If the numbers of atoms on both sides of the equation are equal at this point, the equation is already balanced and you are finished. In this example, they are not the same and you go to the next step.

3. Choose the substance that has the most influence on the equation and insert coefficients in the formulas as needed.

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

4. Inspect the equation and recalculate the numbers of atoms on both sides of the equation. If they are equal, the equation is balanced. If they are not equal, change the coefficients until the equation is balanced.


Balanced EquationsExample:

C + O2 CO2

Example:

HCl + MgBr2 MgCl2 + HBr.

Example:

Al2(SO4)3 + CaCl2 AlCl3 + CaSO4


Balanced EquationsTo be able to write out a word equation you first need to know what all the symbols stand for.

Symbol Meaning+

(s)

(l)

(g)

(aq)

Writing out a chemical equation is similar to writing out a math equation. You need to understand what all the words mean before you write out the symbols and formulas. Once you have determined the chemical equation, you must balance the equation.

ALWAYS BALANCE THE CHEMICAL EQUATION!!!Example:Solid aluminum combines with three chlorine gas to produce solid aluminum chloride.

Example:Methane gas reacts with oxygen forming carbon dioxide gas and water.


Types of Reactions Single Displacement (Replacement) ReactionsIn single displacement reactions, one element replaces another element in a compound.

There are two possible reactions.i. One positive ion replaces another.

Zn + HCl ZnCl2 + H2

ii. One negative ion replaces another.

Cl2 + 2NaBr 2NaCl + Br2

Single displacement reactions can be illustrated using the following general equation.

element + compound element + compound

A + BC B + AC

Synthesis ReactionsTwo or more simple elements or compounds combine to form a more complex compound in synthesis reactions.

2Mg + O2 2MgO

A synthesis reaction can be illustrated using the general equation shown below.

two or more elements or compounds compound

A + B ABTypes of ReactionsDecomposition ReactionsGr. 10 Science Chemistry in Action

During decomposition, one compound splits apart into two (or more pieces). These pieces can be elements or simpler compounds.

2HgO 2Hg + O2

A decomposition reaction can be illustrated using the general equation shown below.

compound two or more elements or compounds

AB A + B

Double Displacement (Replacement) ReactionsIn a double displacement reaction, the two molecules split up and exchange ion partners.

FeS + 2HCl FeCl2 + H2S

A double displacement reaction can be illustrated using the general equation shown below.

compound + compound compound + compound

AC + BD AD + BC

Types of ReactionsCombustion ReactionsCombustion reactions are very rapid reactions of a hydrocarbon (contain hydrogen, carbon and sometimes oxygen) with oxygen gas producing carbon dioxide and water plus a lot of heat.


A combustion reaction can be illustrated using the general equation shown below.

hydrocarbon + oxygen carbon dioxide + water

hydrocarbon + O2 CO2 + H2O

To Summarize:

Type of Reaction General Formula

Synthesis

Decomposition

Single Displacement

Double Displacement

Combustion


Acids and BasesCommon Acids and BasesAcids are used in many industrial processes. Production of paper, steel, and many other products requires the use of acids. Sulphuric and hydrochloric acids are commonly used in such industrial processes.

Bases are important household chemicals used for cleaning and disinfecting. Bases are also used in hairdressing when a "permanent" change is needed to change straight hair to curly hair.

The names and formulas of some common acids and bases are shown below.

Acids Baseshydrochloric acid HCl sodium hydroxide NaOH

sulphuric acid H2SO4 calcium hydroxide Ca(OH)2

nitric acid HNO3ammonium hydroxide NH4OH

Notice that acids tend to have __________ in their formula and bases often have _________ (hydroxide) as the second component in their formula.


Acids and BasesCharacteristics of Acids and Bases

Acids Bases

Taste

Feel

Reaction to Litmus Paper

Other Properties

Reactions

Examples


Acids and BasesA substance that changes colour when added to an acid or base is called an _____________________.

The table below gives you a brief list of the most common indicators.

Indicator Acid BaseLitmus

PhenolphthaleinMethyl Orange

Bromothymol Blue

NeutralizationAn acid and a base, when combined, will ______________________________ each other. Acids will lose their acid properties and bases will lose their base properties.

When an acid reacts with a base, a salt and water are produced.

acid + base salt + water

A _________________ is a compound composed of the __________________ ion of an acid and the ______________________ ion of the base. The water is formed when the hydrogen ion (H+) of the acid combines with the hydroxide ion (OH-) of the base.

Example:

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


Acids and BasesMeasuring the Strength of Acids and Bases The strength of an acid or a base is measured using a scale called pH.

The table below shows the range of pH values for acids and bases.

pH 0-6.9acidic

Measures the strength of acid where a smaller number equals stronger acid and a larger number equals weaker acid

pH 7 (water)neutral Neutral-neither acid nor base

pH 7.1-14basic (alkaline)

Measures the strength of base where smaller number equals weaker base and larger number equals stronger base

Question:Use the pH values described below to determine whether the substance is neutral, a weak or strong acid, or a weak or strong base.

pH = 12 pH = 7 pH = 6 pH = 9 pH = 2


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