1. 4.1 Atomic Theory and Bonding
An _____ is the smallest particle of an ________ that still
has the properties 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 _________________ that is composed of two or more atoms combined in a specific way.
Oxygen and hydrogen are atoms/elements; ___________ is a compound.
A ________________occurs when the arrangement of atoms in compounds changes to form new compounds.
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2. Atoms are made up of smaller particles called subatomic particles.
Atomic Theory
Atoms are made up of smaller particles called subatomic particles.
The nucleus is at the centre of an atom.
The nucleus is composed of ______________________.
___________exist in the space surrounding the nucleus.
# of protons = # of electrons in every atom
Nuclear charge = charge on the nucleus = # of protons
___________________= # of protons = # of electrons
See page 170
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3. Organization of the Periodic Table
In the periodic table ____________are listed in order by their ______________________.
__________are on the left (the transition metals range from group 3 to group 12), ____________ are on the right, and the __________form a “staircase” 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 ___________, or ____________.
All elements in a family have _____________________and bond with other elements in similar ways.
Group 1 = ____________________
Group 2 = ___________________________________
Group 17 = ___________________
Group 18 = ___________________
See page 171
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4. The Periodic Table Where are the following? See page 172 Atomic number
INCREASING REACTIVITY
Where are the following?
Atomic number
Period
Group/Family
Metals
Non-metals
Transition metals
Metalloids
Alkali metals
Alkaline earth metals
Halogens
Noble gases
See page 172
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5. 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 positive ions (_____________).
Some metals (multivalent) lose electrons in different ways.
For example, _____, ___, loses either two (Fe2+) or three (Fe3+) electrons
Non-metals gain electrons and become negative ions (___________).
Atoms gain and lose electrons in an attempt to have the same number of _____________________(electrons farthest from the nucleus) as the nearest noble gas in the periodic table. ~ ~
See page 173
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6. 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.
It has = 18 electrons, and therefore, 18 protons.
It has three electron shells, so it is in period 3.
It has eight electrons in the outer (valence) shell.
What element is this?
18 p
22 n
argon
See page 174
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7. 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.
See page 175
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8. When two atoms get close together, their _______________________.
Forming Compounds
When two atoms get close together, their _______________________.
If the valence electrons can combine ______________________, a compound is formed.
Each atom in the compound attempts to have the stable number of valence electrons as the nearest noble gas.
Metals may lose electrons and non-metals may gain electrons (__________), or atoms may share electrons (__________________).
________________form when electrons are ___________from positive ions to negative ions.
____________________form when electrons are ________between two non-metals.
Electrons stay with their atom but overlap with other shells.
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9. Forming Compounds (continued)
______________are formed between positive ions and negative ions.
Generally, this is a metal (+) and a non-metal (-) ion.
For example, lithium and oxygen form an ionic bond in the compound Li2O.
____________________are formed between two or more non-metals.
Electrons are shared between atoms. +
lithium
oxygen
Electrons are transferred from the positive ions to negative ions
Li+ O2- Li+
lithium oxide, Li2O +
Hydrogen fluoride
See pages
hydrogen
fluorine
electrons are shared
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10. Lewis Diagrams
________________illustrate chemical bonding by showing only an atom’s ____________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.
See page 178
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11. Lewis diagrams can be used to represent _____________________.
Lewis Diagrams of Ions
Lewis diagrams can be used to represent _____________________.
For positive ions, one electron dot is removed from the valence shell for each positive charge.
For negative ions, one electron dot is added to each valence shell for each negative charge.
Square brackets are placed around each ion to indicate _________________. – 2+ –
• •
• •
• •
• •
• •
• •
• •
• •
• •
• •
• •
• •
• •
• •
• •
• • Be Cl Cl Be Cl Cl Be Cl
Each beryllium has two electrons to transfer away, and each chlorine can receive one more electron.
Since Be2+ can donate two electrons and each Cl– can accept only one, two Cl– ions are necessary.
beryllium chloride
See page 179
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12. Lewis Diagrams of Covalent Bonds
Lewis diagrams can also represent ________________.
Like Bohr diagrams, valence electrons are drawn to show sharing of electrons.
The shared ________________are usually drawn as a straight line.
See page 179
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13. Lewis Diagrams of Diatomic Molecules
Diatomic molecules, like O2, are also easy to draw as Lewis diagrams.
• •
• •
• •
• •
• •
• •
• •
• •
• •
• •
• •
• • O O O O O O
Several non-metals join to form diatomic molecules.
Valence electrons are shared, here in two pairs.
This is drawn as a double bond.
See page 180
Take the Section 4.1 Quiz
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14. 4.2 Names and Formulas of Compounds
Ionic ______________are made up of positive and negative ions.
All of the positive and negative ions organize in a pattern.
Negative-positive attract.
Negative-negative and positive-positive repel.
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.
Salt, NaCl
Covalent molecules share electrons.
There is generally no order to the formation of covalent molecules.
These molecules clump 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
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Water, H2O
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15. The Chemical Name and Formula of an Ionic Compound
Ionic __________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 ____________________________.
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.
__________________________
Magnesium oxide is used as a drying agent.
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16. The Chemical Name and Formula of an Ionic Compound (continued)
Writing formulas for ionic compounds:
In an ionic compound, the positive charges balance out the negative charges.
The ratio of positive:negative charges gives the proper formula.
The ratio is _______________________________________.
For example, what is the formula for magnesium phosphide?
Calcium oxide, also known as “quicklime” was once produced by cooking limestone in ancient kilns.
magnesium is Mg2+ phosphorous is P3–
Lowest common multiple of 2 and 3 is 6
3 Mg2+ ions and 2 P3– ions
_____________
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 ________
See page 188
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17. Formula of an Ionic Compound with a Multivalent Metal
Some __________________________are multivalent, meaning they
have more than one ion form.
On the periodic table, the most common 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
______________
Try the name for TiF4
titanium is Ti4+ or Ti3+ fluorine is F–
1 Ti4+ ion and 4 F– ions
_____________________________________
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18. Polyatomic Ions
Some ions, called __________________, are made up of several atoms joined together with covalent bonds.
The whole group has a + or – charge, not the individual atoms.
What is the formula of sodium sulphate?
Na+ and SO42– Na2SO4
What is the name of the compound KClO?
K+ = potassium ClO– = hypochlorite
potassium hypochlorite
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19. 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 non-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 ratio between the ions in the compound.
Covalent molecules have subscripts that show the actual number 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 sugar.
See page 193
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20. Naming Binary Covalent Compounds
_________________compounds (two non-metal atoms) use a system of prefixes.
Covalent compounds may have many or few 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 monoxide, CO2 = carbon dioxide
Write the most metallic atom (farthest left) first
Add -ide to theend of the second atom’s name
What is the chemical formula for the molecule trinitrogen tetrachloride?
____________
What is the name of the molecule Si3P6?
See pages
____________________________________
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21. Comparing Ionic and Covalent Compounds
To determine whether a compound is ionic or covalent:
Examine the formula.
Ionic compounds start with ______________________________________.
Covalent compounds start with __________________________.
If the compound is __________________:
Use the prefix system of naming if the compound is binary and does not start with hydrogen.
If there are more than two different elements, or it starts with H, there is probably a different, simpler name for the covalent molecule.
Check the metal to see if it is multivalent (add a Roman numeral if it is multivalent). Naming starts with the name of the metal atom.
If it ends with a single non-metal, naming will just end in -ide.
If it ends in a polyatomic ion, look up the name/formula.
See pages
Take the Section 4.2 Quiz
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22. 4.3 Balancing Chemical Equations
Chemical reactions result in _____________________.
Chemical changes occur when _________________________.
The original substance(s), called reactants, change into new substance(s) called products.
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)
State of matter
Letters indicate the state of each compound.
(aq) = aqueous/dissolved in water
(s) = solid
( ) = liquid
(g) = gas
Coefficients
Indicate the ratio of compounds in the reaction.
Here, there is twice as much NO and NO2 than as is O2.
See pages
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23. Conservation of Mass in Chemical Change
Chemical change means new compounds are created.
No new matter is created or destroyed; atoms are just rearranged.
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.
________________________________________________________________.
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.
_______________________________________________________________.
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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24. 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 not quantities of atoms.
K + O2  K2O
A balanced chemical equation shows all atoms and their quantities
Balancing ensures that the number of each atom is the same on both sides of the reaction arrow.
Always use the smallest whole-number ratio.
4K + O2  2K2O
See page 206
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25. 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
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
To balance, attempt to find values that equate atoms on both sides
Balanced equation: __________________________________
The same number of atoms must be on each side.
See Page 207
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26. 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 ___________________________________
such as O2, P4 and S8 .
The “special seven” are all diatomic elements
___________________________________
Several common covalent molecules containing hydrogen have _______________that you should know.
For example, methane = CH4, glucose = C6H12O6, ethane = C2H6, ammonia = NH3
See page 208
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27. Strategies for Balancing Equations
Balance chemical equations by following these steps:
Trial and error will work but can be very inefficient.
Balance compounds first and elements last.
Balance one compound at a time.
Only add ____________________; 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
See pages
Take the Section 4.3 Quiz
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