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EO 103 Foundations
Matter: Anything that has mass and volume
Mass: Amount of matter in an object
Weight: Measure of the force of attraction between objects due to mass and gravity
Volume: Amount of space an object takes up
Density: Measurement of how much mass is contained in a given volume
Atoms: Smallest particle of an element that has all the properties of matter:Protons- particles in the nucleus with positive
chargeElectrons- particles orbiting around nucleus with
negative chargeNeutrons- particles in the nucleus with no
charge
Elements: Simplest form of a pure substance Compounds: Two or more elements chemically
combined to form a new substance
Sub-Atomic Particles
Part of Part of AtomAtom
ChargeCharge LocationLocation Mass/SizeMass/Size
ElectronElectron - negative- negative outside outside nucleusnucleus
.0006 amu.0006 amu(too little to (too little to count)count)
ProtonProton + positive+ positive inside inside nucleusnucleus
1 amu1 amu
NeutronNeutron no chargeno charge inside inside nucleusnucleus
1 amu1 amu
Atomic NumberAtomic Number– Equal to # protons = # electronsEqual to # protons = # electrons– Periodic Table is arranged by this Periodic Table is arranged by this
numbernumber
Symbol Symbol – ““Shorthand” for the element – Note Shorthand” for the element – Note
22ndnd letter is always lowercase letter is always lowercase
Atomic Mass NumberAtomic Mass Number – Total AVERAGE mass of Protons + Total AVERAGE mass of Protons +
Neutrons + ElectronsNeutrons + Electrons
17
Cl
35.5
Electrons are arranged in “Shells” around nucleus in predictable locations
Fill “seats” closest to nucleus first (concert – best seats)
“Seats” available Shell #1 2 electrons Shell #2 8 electrons Shell #3 8 electrons Shell #4 18 electrons Shell #5 32 electrons Shell #6 50 electrons
Ex. Carbon has 6 total electrons so…Two electrons on first energy level
Four electrons on second energy level
Question: Could we fit more electrons on the second energy level if there were more electrons in carbon??
17
Cl
35.5
Total Mass of Nucleus36 - 17 = 18 neutrons
Element NameChlorine
Total # of protons and electrons (in a neutral atom)17 protons in nucleus17 electrons orbiting nucleus
Notice: electrons follow energy level rules from previous slide.
(Round Atomic Mass)
Atomic Mass – Fractions?Atomic Mass – Fractions?
Look at Chlorine (atomic number Look at Chlorine (atomic number 17)17)
Atomic mass of 35.5? I dont’ get Atomic mass of 35.5? I dont’ get it!it!
Where does the 35Where does the 35.5 .5 come from?come from?– 0.5 protons? 0.5 neutrons? 0.5 protons? 0.5 neutrons? No No
Atomic Mass = Atomic Mass = averageaverage number of number of protons and neutrons in natureprotons and neutrons in nature
More PracticeMore Practice
Determine the name, number of Determine the name, number of protons, neutrons and electrons for protons, neutrons and electrons for each element shown and draw…each element shown and draw…
15
P
31
8
O
16
26
Fe
56
IsotopesIsotopes
An isotope is a variation of an An isotope is a variation of an element (same protons) but can element (same protons) but can have diff. # of neutronshave diff. # of neutrons
Ex: carbon (atomic mass = Ex: carbon (atomic mass = 12.011)12.011)– Carbon (14) and carbon (12) exist in Carbon (14) and carbon (12) exist in
nature nature
IonsIons Change in Change in electronselectrons which gives an which gives an
atom a atom a charge (+ or -)charge (+ or -) You can only add or subtract You can only add or subtract
electrons! electrons! (protons don’t change)(protons don’t change)
– Ex. Ex. Count the number of electrons below…Count the number of electrons below…
Carbon ion (-1 charge)7 electrons (-)6 protons (+)
Carbon ion (+1 charge)5 electrons (-)6 protons (+)
Neutral Carbon6 electrons (-)6 protons (+)
Valence ElectronsValence Electrons An electron on the outermost energy shell An electron on the outermost energy shell
of an atomof an atom Important to understand because this is a Important to understand because this is a
key factor in how atoms will key factor in how atoms will BONDBOND with with each othereach other
Octet rule – stable atom will have 8 Octet rule – stable atom will have 8 electrons in that outer shellelectrons in that outer shell
Practice – Valence # of Practice – Valence # of – Chlorine?Chlorine?– Neon?Neon?– Nitrogen?Nitrogen?– Oxygen?Oxygen?
a diagram that represents the # of valence electrons in an atom of an element.
The amount of electrons is displayed by dots around the symbol of the element.
Ex.
http://www.fordhamprep.org/gcurran/sho/sho/lessons/lesson38.htm
Ionic- Two elements bond by transferring electrons to create ions that attract together (+ is attracted to - after an electron is transferred)
Covalent- Two elements bond by sharing electrons (strongest bond type)
Metallic- Two metals bond and form a “common electron cloud”. This is a cluster of shared electrons (weakest bond type)
http://www.youtube.com/watch?v=xTx_DWboEVs
http://www.youtube.com/watch?v=1wpDicW_MQQ
http://www.youtube.com/watch?v=D07lflbdmhg
Predicting BondsPredicting Bonds
Ionic Bond = metal to non-metalIonic Bond = metal to non-metal Covalent = non-metal to non-metalCovalent = non-metal to non-metal Metallic = metal to metalMetallic = metal to metal
Do you understand why? HINT: the numbers at the top of the table indicate the # of valence electrons for each column
Oxidation numbers are assigned to each element
They represent a predicted “charge” of an atom/ion when it bonds with another element.
(tells us if the atom would prefer give or take electrons, and how many).
They help us to predict what compounds will form when two elements get together.
Oxidation numbers are labeled like this: Na 1+
O 2-
How to Use Oxidation How to Use Oxidation NumbersNumbers
Oxidation Number indicates the number of electrons lost, gained or shared when bonding with other atoms.
Ex. Na wants to lose an electron. If an electron is lost, it becomes a +1 charge
SO: oxidation number for Na = 1+
Ex. Cl wants to gain an electron. If an electron is gained, it becomes a -1 charge
SO: oxidation number for Cl = 1-
Oxidation NumbersOxidation Numbers
Each column going down the Each column going down the periodic table has elements with periodic table has elements with the same oxidation number.the same oxidation number.
The oxidation numbers are at the top of each column as The oxidation numbers are at the top of each column as shown here:shown here:
1+ 2+ 3+ 4(+/-) 3- 2- 1- 0
Rules for using oxidation Rules for using oxidation numbers to create numbers to create
compoundscompounds1.1. Positive ions can only bond with negative ions and Positive ions can only bond with negative ions and
vice versavice versa2. The sum of the oxidation numbers of the atoms in a 2. The sum of the oxidation numbers of the atoms in a
compound must be compound must be zero zero (the key is to stay balanced)(the key is to stay balanced)
3. If the oxidation numbers are not equal to zero, then 3. If the oxidation numbers are not equal to zero, then you must add additional elements until they balance you must add additional elements until they balance at zero.at zero.
4. When writing a formula the symbol of the Positive 4. When writing a formula the symbol of the Positive (+) element is followed by the symbol of the (+) element is followed by the symbol of the negative (-) element. negative (-) element.
Examples of Forming Examples of Forming CompoundsCompounds
Ex. Na (+1) + Cl (-1) = NaClEx. Na (+1) + Cl (-1) = NaClAre these oxidation numbers already equal to zero? Are these oxidation numbers already equal to zero? If so, you don’t need to add any extra elements to combine them into a compound, so the If so, you don’t need to add any extra elements to combine them into a compound, so the answer is simply NaClanswer is simply NaCl
Ex. H (+1) + O (-2) = HEx. H (+1) + O (-2) = H22OOHow many +1 would you need to balance the -2 to zero?How many +1 would you need to balance the -2 to zero?Since you need 2 atoms of the 1+ to balance the 2- to zero the resulting compound would be Since you need 2 atoms of the 1+ to balance the 2- to zero the resulting compound would be HH22OO
In other words: to combine H with O, you MUST have 2 H to balance the oxidation In other words: to combine H with O, you MUST have 2 H to balance the oxidation numbers to zeronumbers to zero2+ and 2- = ZERO2+ and 2- = ZERO
Ex. Al (+3) + S (-2) = AlEx. Al (+3) + S (-2) = Al22SS33
This one is tricky…we are not even close to balancing + and - to zero.This one is tricky…we are not even close to balancing + and - to zero.
Because of this we must have more than one Al and more than one S in our final equation.Because of this we must have more than one Al and more than one S in our final equation.By using 2 Aluminums instead of just1 we would have 6+By using 2 Aluminums instead of just1 we would have 6+By using 3 sulfers instead of just 1 we would have 6-By using 3 sulfers instead of just 1 we would have 6-Since these are now equal to zero, we combine 2 Aluminums and 3 Sulfers to make AlSince these are now equal to zero, we combine 2 Aluminums and 3 Sulfers to make Al 22SS33
Physical Change: A change that can occur without changing the identity of the substance.
Ex. Solid, Liquid, Gas (Phase change)Plasma
Chemical Change: Process by which a substance becomes a new and different substance
Ex. Fire
Chemical ReactionsChemical Reactions
Chemical Reaction:Chemical Reaction: a process in a process in which the physical which the physical andand chemical chemical properties of the original properties of the original substance substance changechange as new as new substances with different physical substances with different physical and chemical properties are and chemical properties are formedformed
Chemical Reaction BasicsChemical Reaction Basics
H2 + O2 --> H2O
Reactants- substance that enters into a reaction
Products- substance that is produced by a chemical reaction
Reactants Products
Evidence of Chemical Evidence of Chemical ChangeChange
EPOCH is an acronym that stands for evidence EPOCH is an acronym that stands for evidence that a chemical reaction has occurred.that a chemical reaction has occurred.
– – Effervescence (bubbles and/or gives off Effervescence (bubbles and/or gives off gas)gas)
– – Precipitate (solid crystals form)Precipitate (solid crystals form) – – Odor (change of smell is detected)Odor (change of smell is detected) – – Color changeColor change – – Heat (reaction either heats up or cools Heat (reaction either heats up or cools
down)down)
Does sighting evidence of a chemical reaction mean Does sighting evidence of a chemical reaction mean that a chemical reaction has undoubtedly taken place?that a chemical reaction has undoubtedly taken place?
EE
PPOO
CCHH
Types of ReactionsTypes of ReactionsRomance Chemistry :)Romance Chemistry :)
Synthesis-Synthesis- Marriage/Dating Marriage/Dating
A + B = ABA + B = AB
Decomposition-Decomposition- Divorce/Breakup Divorce/Breakup
AB= A + BAB= A + B
Single-Replacement-Single-Replacement- Dance Cut In Dance Cut In
A + BC = AC + BA + BC = AC + B
Double-Replacement- Double-Replacement- Dancing couples Dancing couples switch partners.switch partners.
AB + CD = AC + BDAB + CD = AC + BD
Cartoon ChemistryCartoon Chemistry
This is an example of synthesis
Cartoon ChemistryCartoon Chemistry
This is an example of a decomposition
Cartoon ChemistryCartoon Chemistry
This is an example of a single replacement
Cartoon ChemistryCartoon Chemistry
This is an example of a double replacement
Reaction Types Review…Reaction Types Review…
Match each chemical reaction with one Match each chemical reaction with one of the reaction types on your chemical of the reaction types on your chemical cartoons. cartoons. – Zn + 2HCl Zn + 2HCl H H22 + ZnCl + ZnCl22– NN22 + 3H + 3H22 2NH 2NH33
– 2KI + Pb(NO2KI + Pb(NO33))22 2KNO 2KNO33 + PbI + PbI22
– 2MgCl 2MgCl Mg Mg22 + Cl + Cl22
Atoms cannot be created or destroyed in a chemical reaction.
What goes in must come out. So we must balance equations to
conserve mass.
Rules:We can not add or subtract subscripts
from either side of the equationWe can only add coefficients to the front
of each compound Ex. 2H2 + O2 --> 2H2O
H = 4 H = 4 O=2 O = 2
Before must match After
See “Balancing Act” worksheet for more examples…
Mixtures: Matter that consists of two or more substances mixed but not chemically combined
Solutions: Homogeneous Mixture in which one substance is dissolved into another
Solute = Substance that gets dissolved (ex. Kool-Aid powder)
Solvent = Substance that does the dissolving (ex. Water) Acid: Compound with a pH below 7 that tastes sour and
is a proton donor. Ex. Citrus foods
Base: Compound with a pH above 7 that tastes bitter and is a proton acceptor
Ex. Cleaning Products (soap)
- Solutions can be acidic or basic
- Acids and Bases have unique properties when dissolved in water- Acids = sour taste- Bases = bitter taste
- Indicators are substances that change color when mixed with a solution, which helps to determine if a substance is an acid or a base. (pH paper, Litmus paper, cabbage juice)
Proton donors (H+) Acids contain hydrogen and produce
positive ions (H+) when dissolved in water
Acids = good electrolytes Examples of acids:
Lemon JuiceCitric AcidCarbonic AcidHCl
Proton acceptors Bases contain hydroxide ions (OH-)
when mixed with water. Bases = weak electrolytes Examples of bases:
AmmoniaSoapBleach (chlorine)
Combining Acids and BasesCombining Acids and Bases
-Mixing acids and bases is a balancing -Mixing acids and bases is a balancing act.act.
(like a teeter-totter)(like a teeter-totter)
Acid + Base = neutral (water and salt)Acid + Base = neutral (water and salt)
Combining Acids and BasesCombining Acids and Bases
EXAMPLE:EXAMPLE:
Acid + Base = neutral (water and salt)Acid + Base = neutral (water and salt)
H+H+ + + OH-OH- HOH + Salt HOH + Salt
Acid Base waterAcid Base water
Ex. Ex. HHCl + NaCl + NaOHOH H H22O + O + NaClNaCl
Measuring Acids and BasesMeasuring Acids and Bases
pH scale- used to measure the acidity pH scale- used to measure the acidity of a solution.of a solution.
Measure pH with indicatorsMeasure pH with indicators pH scale goes from 0 – 14pH scale goes from 0 – 14 0 = very acidic0 = very acidic 14 = very basic14 = very basic 7 = neutral7 = neutral
Acids and BasesAcids and Bases