Chemistry CPA Unit 4 Notes: Compounds and Nomenclature West Essex Regional High School 2013-2014...
-
Upload
helen-hamilton -
Category
Documents
-
view
216 -
download
0
Transcript of Chemistry CPA Unit 4 Notes: Compounds and Nomenclature West Essex Regional High School 2013-2014...
Chemistry CPA Unit 4 Notes:
Compounds and Nomenclature
West Essex Regional High School2013-2014
Callahan, Pengitore & Ricafort
NJCCCS & Common Core
• NJCCCS - 5.2.12.B.1:• An atom’s electron configuration, particularly of the outermost electrons, determines how
the atom interacts with other atoms. Chemical bonds are the interactions between atoms that hold them together in molecules or between oppositely charged ions.
• Model how the outermost electrons determine the reactivity of elements and the nature of the chemical bonds they tend to form.
• Common Core LLA: • CCSS.ELA-Literacy.RST.11-12.4: Determine the meaning of symbols, key terms, and other
domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 11–12 texts and topics.
• CCSS.ELA-Literacy.RST.11-12.5: Analyze how the text structures information or ideas into categories or hierarchies, demonstrating understanding of the information or ideas.
• CCSS.ELA-Literacy.RST.11-12.9: Synthesize information from a range of sources (e.g., texts, experiments, simulations) into a coherent understanding of a process, phenomenon, or concept, resolving conflicting information when possible.
Unit Objectives:
Chapter 4• Distinguish the properties of compounds
from those of the elements of which they are composed.
• Compare and contrast the properties of sodium chloride, water, and carbon dioxide
• Model the two types of compound formation, ionic and covalent, at the atomic level
• Demonstrate how and why atoms achieve chemical stability by bonding
• Compare, using examples, the effect of covalent and ionic bondings on the physical properties of compounds
Chapter 5• Apply ionic charge to writing formulas for
ionic compounds.• Apply formulas to name ionic compounds• Interpret the information in a chemical
formula• Compare the properties of covalent and
ionic substances.• Distinguish among allotropes of an
element• Apply formulas to name covalent
compounds.
Element Properties vs. Compounds Properties: What’s the difference?
Sodium and Chlorine• Sodium as an element (Na) –• Shiny, white, soft, solid metal• Melting point - 98°C• Extremely reactive with water and
air!
• Chlorine as an element (Cl)• Pale green, poisonous gas with
choking odor and kills living cells• Extremely hazardous to society
Sodium Chloride (NaCl)• Two dangerous elements combine
to form a safe substance we use each day!• Tiny white crystals (which are
brittle)• Melting point of 800°C!• Not a conductor• Used as table salt, in recipes and as
a food preservative• Natural part of the human diet
Element Properties vs. Compounds Properties: What’s the difference? • Carbon and Oxygen• Carbon as an element (C)
• Nonreactive at room temp• Can be in forms of charcoal, diamonds
and graphite
• Oxygen as an element (O)• Colorless, odorless, tasteless gas • Humans need it to breath• Rusting is due to reaction with oxygen
• Carbon Dioxide (CO2)• Colorless, odorless gas at room
temperature• More dense than air• When cooled below -80°C it goes from a
gas right to a white solid• Can make Carbon Dioxide simply by
burning carbon in air• Used in photosynthesis• Application and Critical thinking -
• What do power plants use to create energy?
• How does the burning of that substance produce carbon dioxide?
• Why do you think an abundance of carbon dioxide is bad for our atmosphere?
Element Properties vs. Compounds Properties: What’s the difference? • Hydrogen and Oxygen• Hydrogen (H) as an element• Colorless, odorless, tasteless gas• Reactive and reacts vigorously
with other elements
• Oxygen (O) – we learned about that above.
• Water (H2O)• Universal solvent• Important everywhere – from
rivers from blood • Only one of three substances that
occurs naturally in the environment in all three states of matter (ice, water, vapor)• Important component of nearly all
biochemical reactions
Why and how do you suppose elements are mostly found in compounds and not alone?• Think about their valence electrons! And quietly answers in the space
provided.
Electrons Review
• Atomic number = number of Electrons• Electrons vary in the amount of energy they possess, and they
occur at certain energy levels or electron shells• Electron shells determine how an atom behaves when it
encounters other atoms• The first shell wants a maximum of 2 electrons, and all others
want a maximum of 8 electrons. • Valence shell filling is the ultimate goal of ALL atoms. • They bond and react IN ORDER to fill their valence shell.
Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons
C would like to N would like toO would like to
Gain 4 electronsGain 3 electronsGain 2 electrons
Why are electrons important?
• Elements have different electron configurations• Different electron configurations mean different levels of bonding
Take a look at the diagram and answer the following questions:
1. Review: A. X would be the electron dot formula for
1) Na 2) K 3) Al
B. X would be the electron dot formula
1) B 2) N 3) P 2. Exercise – draw the Lewis dot structures for the first 18 elements on the periodic
table.3. What elements do you see that could “hook up” with one another to create a
“partnered” 8-valence electron shell?
Electron Dot Structures
Symbols of atoms with dots to represent the valence-shell electrons
1 2 13 14 15 16 17 18
H He:
Li Be B C N O : F :Ne :
Na Mg Al Si P S :Cl :Ar :
Atoms form partnerships by making bonds1. Atoms share or exchange their electrons with
another atom or atoms in order to share a completed valence shell.
2. When they “hook up”, it’s called a bond.3. There are two types of bonds:
1. Ionic2. Covalent
Properties of Ionic Compounds
• Hard solids that have a crystal appearance and structure at room temperatures • Are referred to as “salts”• Ions are held together in very
organized and tight/strong bonds which take an enormous amount of energy to break• Soluble in water• Electrolytes – conduct electricity
when dissolved in water
Ionic Bonds
• bond formed between two ions by the transfer of electrons• Ionic compounds form when metals bond to nonmetals.•Metals loose or give their electrons away to match the
number of valence electrons of their nearest noble gas, forming cations• Nonmetals gain or take electrons from a metals to match
the number of valence electrons of their nearest noble gas forming anions
More on Metals Loosing…
Positive ions form when the number of electrons are less than the number of protons
Group 1 metals ion 1+
Group 2 metals ion 2+
• Group 13 metals ion 3+
Formation of Sodium Ion
Sodium atom Sodium ion Na – e Na +
1st shell: 2 1st shell: 22nd shell: 8 2nd shell: 83rd shell: 1 ( = Ne’s configuration!)
(2-8-1) (2-8) 11 p+ 11 p+
11 e- 10 e-
0 1+
Formation of Magnesium Ion
Magnesium atom Magnesium ion
Mg – 2e Mg2+
1st shell: 2 1st shell: 22nd shell: 8 2nd shell: 83rd shell: 2 ( = Ne’s configuration!)
(2-8-2) (2-8)
12 p+ 12 p+
12 e- 10 e-
0 2+
Some Typical Ions with Positive Charges (Cations)
Group 1 Group 2 Group 13
H+ Mg2+ Al3+
Li+ Ca2+
Na+ Sr2+
K+ Ba2+
Learning Check
A. Number of valence electrons in aluminum1) 1 e- 2) 2 e- 3) 3 e-
B. Change in electrons for Al’s octet1) lose 3e- 2) gain 3 e- 3) gain 5 e-
C. Ionic charge of aluminum 1) 3- 2) 5- 3) 3+
Solution
A. Number of valence electrons in aluminum3) 3 e-
B. Change in electrons for octet1) lose 3e-
C. Ionic charge of aluminum 3) 3+
Learning Check
Give the ionic charge for each of the following:A. 12 p+ and 10 e-
1) 0 2) 2+ 3) 2-
B. 50p+ and 46 e-1) 2+ 2) 4+ 3) 4-
C. 15 p+ and 18e-2) 3+ 2) 3- 3) 5-
More on Nonmetals Gaining…
In ionic compounds, nonmetals in 15, 16, and 17 gain electrons
from metals
Nonmetals add electrons to achieve the octet arrangement
Nonmetal ionic charge:
3-, 2-, or 1-
Fluoride Ion
unpaired electron octet 1 -
: F + e : F :
1st shell: 2 1st shell: 22nd shell: 7 2nd shell: 8(2-8-1) ( = Ne’s configuration!)
(2-8)
9 p+ 9 p+
9 e- 10 e- 0 1 -
ionic charge
Ions happen because of bonding
• Ionic Bond:•Between atoms of metals and nonmetals with
very different electronegativity•Bond formed by transfer of electrons•Produce charged ions all states. •Conductors•Have high melting point.•Examples; NaCl, CaCl2, K2O
Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.
Practice – Predict the ion that will form with each element listed below. Show your work!!!• 1. Ca
• 2. P
• 3. S
• 4. K
• 5. Br
Properties of Covalent Compounds• Composed of molecules held together by strong forces called
covalent bonds which aren’t based on charge.• Molecules are held together by intermolecular forces which are
weaker than the force that hold ions together.• Tend to be liquids or gases at room temperature.• Not conductors of electricity• Don’t usually dissolve in water
Covalent Bond
•bond formed by the sharing of electrons•Between nonmetallic elements of similar
electronegativity.• Formed by sharing electron pairs• Stable non-ionizing particles, they are not conductors
at any state• Examples; O2, CO2, C2H6, H2O, SiC
Oxygen AtomOxygen Atom Oxygen AtomOxygen Atom
Oxygen Molecule (O2)
O2 is an example of a nonpolar covalent bond
- water is a polar molecule because oxygen is more electronegative than hydrogen, and therefore electrons are pulled closer to oxygen.
Practice: Tell whether the examples below are elements, ionic compounds or covalent compounds.1. Potassium (K)
2. Lithium fluoride (LiF)
3. Carbon dioxide (CO2)
4. Oxygen gas (O2)
5. Cobalt (Co)
Naming a Binary Ionic CompoundA binary compound is one in which contains only two elements. To name a binary compound,• identify the cation and anion.• name the cation first• name of the anion second, but change the ending to “-ide”
Examples: Sodium + Chlorine = Sodium ChlorideMagnesium + Oxygen = Magnesium Oxide
47
Complete the names of the following ions. Ba2+ Al3+ K+
_________ __________ _________
N3 O2 F
_________ __________ _________
P3 S2 Cl _________ __________ _________
Learning Check
Practice – Naming Binary Ionic Compounds1. Lithium + Nitrogen2. KCl3. Strontium + Selenium4. MgCl2
5. Calcium + Chlorine6. Al2O3
Writing Formulas for Binary Ionic Compounds
1. Write the symbol for the metal first with the charge• Example: Magnesium, Mg2+
2. Write the symbol for the nonmetal next with the charge• Example: Chlorine, Cl 1-
3. Crisscross the number of the charge (don’t write a number if the charge is -1 or +1)• Example: Mg2+ Cl 1-
MgCl2• All compounds are neutral, so the charges must add to ZERO:
1(+2) + 2(-1) = 2 – 2 = 0
50
Charges of Representative Elements
Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings
Learning CheckWrite the formulas and names for compounds of the following ions:
Br− S2− N3−
Na+
Al3+
EXAMPLES
Different Charges:
1. Aluminum sulfideAl+3 S-2
Al2S3
2. Calcium chlorideCa+2 Cl-1
CaCl2
Equal but opposite charges:
3. Magnesium oxide
Mg+2 and O-2
Mg2O2 this can be reduced to
MgO
Practice – forming binary ionic compounds
Calcium and Oxygen
Aluminum and Fluorine
Boron and Oxygen
Strontium and Nitrogen
Barium and Selenium
Ions with charges
Ca 2+ O2-
Criss-cross and drop Charge
Formula:
Ca2O2
Reduces to 0:
CaOName:
Naming when the metal forms more than one chargeLook at the Periodic Table – some elements have more than one charge –
Transition Metals Ex: Copper +1 or +2
• Roman Numerals are used to indicate the charge. Copper (I) or Copper (II)
Cu+1 or Cu+2
• Example: Copper (Cu+2) and Chlorine (Cl1-)• Writing the name: Copper (II) chloride• Writing the formula: CuCl2
Naming compounds that have metals with multiple charges – THE TRICK… • Determine the charge by working backwards•Write the charge in roman numerals in the name
CuF2• Copper is either +1 or +2 charge• In this case it is +2 since there are two Fluorine atoms
for every one copper (F is always -1 charge)• Copper (II) Fluoride
Practice – write the formula and name
Chromium (2+) and Chlorine
Lead (2+) and Oxygen
Manganese (3+) and iodine
Iron (3+) and Oxygen
Write the ions with their charges
Criss-Cross and drop the charge –Formula
Name
Practice – Predict the charge & formula from the formula
Iron (III) Chloride Lead (IV) Fluoride Nickel (III) Bromide Mercury (II) oxide
Write the Ions Cl 1-
Criss- cross and drop chargeFormula
Polyatomic Ions
•What are they?•An ion that has two or more different elements •The ion is a group of atoms held together by covalent bonds. •The group as a whole has a charge, so it acts just like an anion, which the exception of the Ammonium (NH4)+ ion
How To Handle Polyatomic Ions…•Always include parenthesis around these ions• End in –ate or –ite• Exceptions – Hydroxide, Cyanide, Ammonium
• Found on the back of your periodic table!
Naming Compounds with Polyatomic Ions•Metal bonded to a polyatomic ion
Al2(SO4)3
1.Name the metal2.Name the polyatomic ion as it appears on the back
of your periodic table
Writing Formulas for Compounds with Polyatomic Ions1. Write the symbol for the metal and charge2. Write the polyatomic ion in parenthesis and with
charge outside3. Criss-cross the charges
Practice making formulas for compounds with polyatomic ions
Magnesium Hydroxide Sodium Sulfate Calcium Carbonate Aluminum Sulfite
Write the Ions with their charges – put polyatomics in parenthesis with charge outside!!
Mg2+ (OH)-
Criss-cross and drop charge outside parenthesisFormula
Mg(OH)2
Naming Molecular (Covalent) Compounds
• Two non-metals bonded together; shared bond of electrons
Example: CO2 = carbon dioxide•Prefixes are used to express the number of each
element• The second nonmetal ends in –ide•Never reduce!!
PrefixesNumber Prefix1 mono-2 di-3 tri-4 tetra-5 penta-6 hexa-7 hepta-8 octa-9 nona-10 deca-
ATTENTION!!!• The prefix mono- is not used with the first
named element• Use the back of your periodic table to help
you
Practice Writing Formulas for Covalent/Molecular Compounds
Name pentacarbon decahydride tetrasulfur heptoxide carbon monobromide Iodine trichloride
Compound
Naming and Writing Formulas for Hydrocarbons• Compounds containing Carbon are organic compounds• Hydrocarbon is an organic compound that contains only Carbon (C)
and Hydrogen (H)• Hydrocarbons occur naturally as fossil fuels such as coal, natural gas,
and petroleum• All carbon atoms can form 4 covalent bonds.