4.1 Atomic Theory and Bonding - Mr. C's Math and Science...

Chapter 4 Notes Science 10 Name: ____________________

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4.1 Atomic Theory and Bonding

Atomic Theory

• An atom is the smallest particle of an element that still has the

___________ of that element

• 50 million atoms, lined up end to end = 1 cm

• An atom = proton(s) + neutron(s) + electron(s)

• Atoms join together to form ___________.

• A compound is a ___________ substance that is composed of two or

more atoms combined in a specific way.

• Oxygen and hydrogen are atoms/___________; H2O is a compound.

• A chemical change occurs when the arrangement of atoms in

compounds changes to form new compounds.

• Atoms are made up of smaller particles called ___________ particles.

• The nucleus is at the ___________ of an atom.

• The nucleus is composed of ___________ and ___________.

• ___________ exist in the space surrounding the nucleus.

• # of protons = # of electrons in every atom

• Nuclear charge = charge on the nucleus = # of protons

• ___________ number = # of protons = # of electrons


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Learning Check

1. What is the electric charge on each of the three subatomic particles?

2. Which two subatomic particles have nearly equal mass?

3. Which particle determines the nuclear charge?

4. Which two subatomic particles are present in equal number in every atom of the same element?

Organization of the Periodic Table

� In the periodic table elements are listed in order by their _______ number.

� Metals are on the _____ (the transition metals range from group 3 to group

12), non-metals are on the _____, and the metalloids form a “__________”

toward the right side.

� Rows of elements (across) are called ___________.

• All elements in a period have their electrons in the same general area

around their nucleus.

� Columns of elements are called groups, or ___________.

• All elements in a family have similar ___________ and bond with

other elements in similar ways.

· Group 1 = ___________ metals

· Group 2 = alkaline ___________ metals

· Group 17 = the ___________

· Group 18 = ___________ gases

With a partner find the following on the periodic table? (p. 172)

• Atomic number

• Period

• Group/Family

• Metals

• Non-metals

• Transition metals

• Metalloids

• Alkali metals

• Alkaline earth

metals

• Halogens

• Noble gases


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Periodic Table and Ion Formation

� Atoms gain and lose electrons to form bonds.

• The atoms become electrically charged particles called ___________.

• Metals lose electrons and become ___________ ions (___________).

o Some metals (_______valent) lose electrons in different ways.

o For example, iron, Fe, loses either two (Fe2+

) or three (Fe3+

)

electrons

• Non-metals gain electrons and become _________ ions (________).

• Atoms gain and lose electrons in an attempt to have the same

number of valence electrons (electrons farthest from the nucleus) as

the nearest noble gas in the periodic table.

Fourth Period or Row

Checking for Understanding

1. (a) What is another name for each row in the periodic table?

(b) What is another name for each column or group in the periodic table? 2. Which group of metals is more reactive, the alkali metals or the alkaline earth metals? 3. List all five halogen elements.

4. Name the first and the last transition metal in period 4.


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Bohr Diagrams

• Bohr diagrams show how many electrons appear in each

electron shell around an atom.

� Electrons in the outermost shell are called __________ __________.

Think of the shells as being 3-D like spheres, not 2-D like circles

What element is this?

• It has 2 + 8 + 8 = 18 electrons, and 18 protons.

• It has three electron shells, so it is in period 3.

• It has eight electrons in the outer (valence) shell.

Patterns of Electron Arrangement in Periods and Groups

Electrons appear in shells in a very predictable manner.

• There is a maximum of two electrons in the first shell, eight in the 2nd shell,

and eight in the 3rd shell.

• The period number = the number of shells in the atom.

• Except for the transition elements, the last digit of the group number = the

number of electrons in the valence shell.

• The noble gas elements have full electron shells and are very stable.


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Practice Problems

Use the periodic table in Figure 4.3 on page 172 to help you answer the following questions.

1. Based on the patterns of the periodic table, identify the number of occupied shells for each of

the following elements.

(a) calcium, Ca

(b) krypton, Kr

(c) sulfur, S

(d) iodine, I

2. Based on the patterns in the periodic table, identify the number of valence electrons for each

of the following elements.

(a) chlorine, Cl

(b) magnesium, Mg

(c) strontium, Sr

(d) bromine, Br

Forming Compounds

• When two atoms get close together, their ___________ electrons interact.

� If the valence electrons can combine to form a low-energy ________, a

compound is formed.

� Each atom in the compound attempts to have the ___________ number

of valence electrons as the nearest ___________ gas.

� Metals may ___________ electrons and non-metals may ___________

electrons (ionic bond), or atoms may share electrons (covalent bond).

• Ionic bonds form when electrons are ___________ from positive ions to

negative ions.

• Covalent bonds form when electrons are _________between two non-metals.

� Electrons stay with their atom but overlap with other shells.


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Ionic bonds are formed between positive ions and negative ions.

� Generally, this is a ___________ (+) and a ____-metal (-) ion.

� For example, lithium and oxygen form an ionic bond in the compound

Li2O.

Covalent bonds are formed between two or more ____-metals.

� Electrons are ___________ between atoms.

Learning Check 1. How many valence electrons are there in an atom of carbon?

2. (a) How many electrons in phosphorus are paired?

(b) How many are single?

3. How many electrons are there in an ion of S

2-?

4. What ion has 36 electrons and a charge of 1- ?


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Lewis Diagrams

• Lewis diagrams illustrate chemical bonding by showing only an atom’s

valence electrons and the chemical symbol.

• Dots representing electrons are placed around the element symbols at the

points of the compass (north, east, south, and west).

• Electron dots are placed singly until the fifth electron is reached then they

are paired.

Lewis Diagrams of Ions

• Lewis diagrams can be used to represent ions and ionic bonds.

� For positive ions, one electron dot is ___________ from the valence

shell for each positive charge.

� For negative ions, one electron dot is ___________ to each valence shell

for each negative charge.

� ___________ brackets are placed around each ion to indicate transfer of

electrons.


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Lewis Diagrams of Covalent Bonds

• Lewis diagrams can also represent covalent bonds.

� Like Bohr diagrams, ___________ electrons are drawn to show sharing

of electrons.

� The shared pairs of electrons are usually drawn as a ___________ line.

Lewis Diagrams of Diatomic Molecules

• Diatomic molecules, like O2, are also easy to draw as Lewis diagrams.

4.1 Practice Quiz

http://www.bcscience.com/bc10/pgs/quiz_section4.1.htm


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Magnesium oxide is used as a drying agent.

4.2 Names and Formulas of Compounds

• Ionic compounds are made up of positive and negative ions.

� All of the positive and negative ions organize in a

pattern.

� Negative-positive ___________.

� Negative-negative and positive-positive ___________.

� Ionic compounds form from the inside out as solid

crystals.

� Ionic compounds are like a solid stack of bricks.

� A salt shaker contains thousands of small pieces of NaCl.

• Covalent molecules share electrons.

� There is generally no order to the formation of covalent ___________.

� These molecules ___________ together as solids, liquids or gases.

� Covalent molecules are like a play-pit full of plastic balls.

� Each plastic ball = 1 covalent molecule of H2O

The Chemical Name and Formula of an Ionic Compound

• Ionic compounds are composed of positive ions and negative ions.

� The name of an ionic compound = positive ion + negative ion-ide.

� For example, an ionic compound forms between magnesium and

oxygen.

� The positive ion is the first part of the

name, magnesium.

� The negative ion forms part of the

ending of the name, oxygen.

� Add -ide to the end of the name to form

______________________.


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Magnesium phosphide is used in

fumigation to control insects and

rodents.

• Ionic formulas are based on the ions of the atoms involved.

� Remember the naming principles above.

� For example, what is the name of Ca3N2?

� Ca, the positive ion, is calcium.

� N, the negative ion, is nitrogen.

� Drop the end of the anion and add -ide.

______________________

Practice Problems

Write the names of the following ionic compounds.

1. (a) Li3N

(b) MgBr2

(c) Ag2O

(d) RbF

(e) AgI

(f) AlBr3

(g) CaI2

(h) GaI3

(i) Ag3N

(j) MgSe

(k) Ca3P2

(l) Na2O

(m) CdS

(n) Sr3P2

Writing formulas for ionic compounds:

• In an ionic compound, the positive charges ________out the negative charges.

• The ratio of positive: negative charges gives the proper formula.

� The ratio is always written in ___________ form.

• For example, what is the formula for magnesium phosphide?

� magnesium is Mg2+

phosphorous is P3–

� Lowest common multiple of 2 and 3 is 6

� 3 Mg2+

ions and 2 P3–

ions

� Mg3P2

• Try the formula for calcium oxide.

� calcium is Ca2+

oxygen is O2–

� 1 Ca2+

ion and 1 O2–

ions

� Ca2O2, which is simplified and written as CaO

Or simply criss-cross and then reduce


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Practice Problems

1. Write the formulas of the compounds containing the

following ions.

(a) Na+

with Br-

(b) Zn2+

with I-

(c) K+ with S

2-

(d) Al3+

with S2-

(e) Ca2+

with O2-

(f) Al3+

with P3-

2. Write the formulas of the following ionic compounds.

(a) strontium nitride

(b) lithium oxide

(c) silver sulfide

(d) barium phosphide

(e) sodium nitride

(f) potassium selenide

(g) cesium sulfide

(h) aluminum nitride

(i) zinc oxide

(j) aluminum iodide

(k) lithium fluoride

(l) sodium sulfide

(m) zinc phosphide

(n) magnesium chloride

Formula of an Ionic Compound with a Multivalent Metal

• Some transitional metals are _______________, meaning they have more than

one ion form.

� On the periodic table, the most ________form of the ion is listed on top.

� In the name of the compound, Roman numerals are used following the

positive ion to indicate which ion was used.

� For example, what is the formula manganese (III) sulphide?

� This manganese is Mn3+

. sulfur is S2–

� Lowest common multiple of 3 and 2 is 6

� 2 Mn3+

ions and 3 S2–

ions

� Mn2S3

� Try the name for TiF4

� titanium is Ti4+

or Ti

3+ fluorine is F

–

� 1 Ti4+

ion and 4 F–

ions

� titanium (IV) fluoride


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Practice Problems

1. Write the formulas of the following compounds containing multivalent metals.

(a) copper(I) nitride

(b) iron(II) phosphide

(c) manganese(II) oxide

(d) manganese(IV) oxide

(e) chromium(II) bromide

(f) chromium(III) bromide

(g) lead(IV) chloride

(h) iron(III) phosphide

(i) tin(II) sulfide

(j) tin(II) nitride

(k) tin(IV) nitride

(l) mercury(II) fluoride

(m) copper(I) iodide

(n) copper(II) iodide

(o) copper(II) selenide

Each of these compounds contains a multivalent metal ion. That means that the

name of the metal ion will contain a Roman numeral, which you will need to

determine. Write the names of the following compounds.

2. (a) Fe2O3

(b) PbF4

(c) FeI2

(d) HgI2

(e) Hg3N2

(f) Sn3P4

(g) MnS

(h) MnS2

(i) VCl5

(j) Ni2S3

(k) NiS

(l) Mo2O3

(m)UCl6

(n) ReF7

(o) TiS2

I, II, III, IV, V, VI, VII, VIII, IX, X

1, 2, 3, 4, 5 , 6, 7, 8, 9, 10


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Polyatomic Ions

• Some ions, called polyatomic ions, are made up of several atoms joined

together with covalent bonds.

• The ___________ group has a + or – charge, not the ___________ atoms.

What is the formula of sodium sulphate?

Na+ and SO4

2– ___________

What is the name of the compound KClO?

K+ = potassium ClO

– = hypochlorite

______________________

Practice Problems

Refer to Table 4.11, Names, Formulas, and Charges of Some Polyatomic Ions, as

you do these problems.

1. Write the names of the following compounds with polyatomic ions.

(a) KCH3COO

(b) Ca(CH3COO)2

(c) (NH4)3P

(d) (NH4)3PO4

(e) Al(OH)3

(f) Fe(OH)3

(g) K2CrO4

(h) K2Cr2O7

(i) Ca(HCO3)2

(j) Mg3(PO4)2


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2. Write the formulas of the following compounds with polyatomic ions.

(a) potassium permanganate

(b) sodium chromate

(c) ammonium nitrate

(d) lithium hydroxide

(e) aluminum hydroxide

(f) lead(II) perchlorate

(g) iron(III) hydrogen sulfide

(h) vanadium(V) nitrate

(i) magnesium acetate

(j) tin(II) cyanide

Names and Formulas of Covalent Compounds

• Covalent compounds, also called ___________, rely on the chemical formula

to reveal the components of the molecule.

� Covalent compounds are made up of two or more _____-metals.

� Names may reveal the components, but often they do not.

� Subscripts mean something different in covalent compounds

� Ionic compounds subscripts show the smallest

whole-number _______ between the ions in the compound.

� Covalent molecules have subscripts that show the

___________ ___________of atoms in the molecule.

� What is the chemical formula for the molecule ethanol?

� C2H6O, a name that must be memorized or looked up when

needed.

� What is the name of the molecule C12O22H11?

� Sucrose, also called table ___________.


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Naming Binary Covalent Compounds

Binary covalent compounds (two non-metal atoms) use a

system of ___________.

• Covalent compounds may have _____ or ___ atoms

sharing electrons.

• CH4 = methane and C25H52 = candle wax

• Prefixes are often used before the atom name to

indicate the number of atoms in the molecule.

• CO = carbon ____xide, CO2 = carbon ___oxide

• Write the most metallic atom (farthest left)

first

• Add -ide to the end of the second atom’s

name

What is the chemical formula for the molecule trinitrogen tetrachloride?

What is the name of the molecule Si3P6?

Practice Problems

1. Write the names of the following compounds.

(a) N2O

(b) CO2

(c) PI3

(d) PCl5

(e) SO2

(f) N2O4

(g) P4S10

(h) S2F10

(i) NI3

(j) NO

2. Write the formulas of the following compounds.

(a) nitrogen tribromide

(b) sulfur hexafluoride

(c) dinitrogen tetrasulfide

(d) oxygen difluoride

(e) carbon tetraiodide

(f) sulfur trioxide


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(g) phosphorus pentabromide

(h) diiodine hexachloride

(i) dichlorine monoxide

(j) xenon hexafluoride

Comparing Ionic and Covalent Compounds

To determine whether a compound is ionic or covalent:

1. Examine the formula.

• Ionic compounds start with a _______or the ___________ion.

• Covalent compounds start with a ____-metal.

2. If the compound is covalent:

• Use the _______system of naming if the compound is _______

and does ____start with _______.

• If there are more than two different elements, or it starts with

H, there is probably a different, simpler name for the covalent

molecule.

3. If the compound is ionic:

• Check the metal to see if it is ___________ (add a __________

numeral if it is multivalent). Naming starts with the name of

the metal atom.

• If it ends with a single ____-metal, naming will just end in -ide.

• If it ends in a ___________ion, look up the name/formula.

Practice Problems

1. Identify each of the following compounds as either ionic or covalent.

(a) (NH4)2S

(b) OCl2

(c) SnCl2

(d) NaNO3

(e) N2O3

(f) SCl2

(g) NBr3

(h) FeF2

2. The compounds in each group below have similar–looking formulas.

However, they may have very different names. Some in each group are ionic,

while others are covalent.

Classify and name each compound.

(a) VO2 NO2


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(b) CrBr2

CdBr2

SBr2

(c) Na2Cr2O7

Na2CrO4

Cr2O3

N2O3

(d) SO3

Li2SO3

Li2SO4

SO2

4.2 Practice Quiz

http://www.bcscience.com/bc10/pgs/quiz_section4.2.htm

4.3 Balancing Chemical Equations

• Chemical reactions result in chemical changes.

• Chemical changes occur when new substances are created.

• The original substance(s), called ___________, change into new substance(s)

called ___________.

• Chemical reactions can be written in different ways.

� A word equation:

Nitrogen monoxide + oxygen → nitrogen dioxide

� A symbolic equation:

2NO(g) + O2(g) → 2NO2(g)

Coefficients - Indicate the ratio of

compounds in the reaction.

Here, there is twice as much NO and NO2

than as is O2.

State of matter - Letters indicate the

state of each compound.

(aq) = aqueous/dissolved in water

(s) = solid

(l ) = liquid

(g) = gas


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Conservation of Mass in Chemical Change

Chemical change means new compounds are ___________.

� No new matter is created or ___________; atoms are just ___________.

� All of the matter in the reactants = all of the matter in the products.

� John Dalton, 200 years ago, realized that atoms simply rearrange

themselves during chemical reactions.

� Number of each atom in reactants = number of each atom in products.

The law of conservation of mass:

� In chemical reactions, atoms are neither created nor destroyed.

� This law was developed by Antoine and Marie-Anne Lavoisier in the

1700s.

� Mass of reactants = mass of products

Learning Check

1. What is the definition of a chemical reaction?

If you could collect and measure all of the

exhaust from this car, you would find that

mass of reactants (gas + O2) = mass of

products (exhaust).


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2. What are two ways a chemical equation may be written?

3. What ratio can you determine using the coefficient in a chemical formula?

4. What are the four abbreviations for a compound’s state of matter?

5. According to the law of conservation of mass, what does the total mass of the

products in a chemical reaction equal?

Writing and Balancing Chemical Equations

The simplest form of chemical equation is a word equation.

� Potassium metal + oxygen gas → potassium oxide

A skeleton equation shows the formulas of the elements/compounds.

• A skeleton equation shows atoms, but ___________quantities of atoms.

� K + O2 → K2O

A balanced chemical equation shows all atoms and their ___________

� Balancing ensures that the number of each atom is the same on both

sides of the reaction arrow.

� Always use the ___________whole-number ratio.

� 4K + O2 → 2K2O


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Learning Check

Refer to the following balanced chemical equation to answer these questions:

3H2 + N2 ➔ 2NH3

1. List the names of the reactants.

2. Give the formula of the product.

3. How many molecules of hydrogen (H2) will combine exactly with one molecule

of nitrogen (N2)?

4. How many molecules of nitrogen are required to produce 10 molecules of

ammonia (NH3)?

5. What is the symbol that means “produces” in a chemical reaction?

Counting Atoms to Balance an Equation

Using the law of conservation of mass, we can count atoms to balance the

number of atoms in chemical equations.

• Word equation: methane + oxygen → water + carbon dioxide

• Skeleton equation: CH4 + O2 → H2O + CO2


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To balance the compounds, take note of how many atoms of each element occur

on each side of the reaction arrow.

Skeleton equation: CH4 + O2 → H2O + CO2

1 carbon, 4 hydrogen, 2 oxygen → 1 carbon, 2 hydrogen, 3 oxygen

� To balance, attempt to find values that equate atoms on both sides

� Balanced equation: CH4 + 2O2 → 2H2O + CO2

1 carbon, 4 hydrogen, (2×2) oxygen → 1 carbon, (2×2) hydrogen, (2×1)+2 oxygen

Practice Problems

List the total number of each type of atoms in the following reactants.

1. 2H2O + 2NaF

2. 3Br2 + 2FeI3

3. Pb(NO3)2 + 2NaI

4. 2K3PO4 + 3(NH4)2SO4


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Hints for Writing Word Equations

Word equations require careful examination to be

written correctly.

� The chemical symbol is used for most elements not

in a compound.

� Be careful of diatomic and polyatomic elements

such as O2, P4 and S8 .

� The “special seven” are all diatomic elements

• H2, N2, O2, F2, Cl2, Br2, I2

� Several common covalent molecules containing

hydrogen have common names that you should

know.

� For example, methane = CH4, glucose = C6H12O6,

ethane = C2H6, ammonia = NH3

Strategies for Balancing Equations

Balance chemical equations by following these steps:

• Trial and error will work but can be very ________________.

• Balance compounds ___________and elements ___________.

• Balance one compound at a time.

• Only add coefficients; NEVER change ___________.

• If H and O appear in more than one place, attempt to balance them LAST.

• Polyatomic ions (such as SO42–

) can often be balanced as a whole group.

• Always double-check after you think you are finished.

• Balance the following:

� Fe + Br2 → FeBr3

� Sn(NO2)4 + K3PO4 → KNO2 + Sn3 (PO4)4

� C2H6 + O2 → CO2 + H2O


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Practice Problems Balance each of the following skeleton equations.

1. (a) NaI + AlCl3 ➔ NaCl + AlI3

(b) Li + Br2 ➔ LiBr

(c) CH4 + O2 ➔ CO2 + H2O

(d) PbO ➔ Pb + O2

(e) Na4C + Ca ➔ Na + Ca2C

(f) C3H8 + O2 ➔ CO2 + H2O

(g) Ca(NO3)2 + Cu2SO4 ➔ CaSO4 + CuNO3

(h) NaN3 ➔ Na + N2

(i) Mg(ClO4)2 + Na ➔ NaClO4 + Mg

2. Write the skeleton equation for each of the following reactions.

Then balance each of the equations.

(a) nitrogen monoxide + oxygen ➔ nitrogen dioxide

(b) iron(III) bromide + sodium hydroxide ➔ sodium bromide + iron(III) hydroxide

(c) methane + oxygen ➔ carbon dioxide + water

(d) calcium nitrate + potassium carbonate ➔ potassium nitrate + calcium carbonate

(e) phosphorus trichloride + chlorine ➔ phosphorus pentachloride

(f) potassium permanganate +nickel(II) nitrate ➔ potassium nitrate + nickel(II) permanganate

(g) iron + copper(II) chloride ➔ iron(II) chloride + copper

4.3 Practice Quiz at http://www.bcscience.com/bc10/pgs/quiz_section4.3.htm

4.1 Atomic Theory and Bonding - Mr. C's Math and Science...

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