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The AtomThe Atom
http://www.youtube.com/watch?v=Uy0m7jnyv6U
III.III. Subatomic ParticlesSubatomic ParticlesA. Atomic NumberA. Atomic NumberB. Mass Number and IsotopesB. Mass Number and IsotopesC. Electrons and IonsC. Electrons and IonsD. Nuclear and Hyphenation NotationD. Nuclear and Hyphenation NotationE. Average Atomic MassE. Average Atomic Mass
IV.IV. Weighing and Counting AtomsWeighing and Counting AtomsA. Mole AtomsA. Mole AtomsB. Mole MassB. Mole MassC. Mass AtomsC. Mass Atoms
Electron
Proton
Neutron
Name Symbol ChargeRelative mass
Actual mass (g)
e-
p+
n0
-1
+1
0
0
1amu
9.11 x 10-28
1.67 x 10-24
1.67 x 10-24
III.III. Subatomic ParticlesSubatomic ParticlesA. Comparing ParticlesA. Comparing Particles
1amu
1. 1. Atomic numberAtomic number
1. the number of protons in the 1. the number of protons in the nucleus of an atomnucleus of an atom
a. identifies the elementa. identifies the element
b. no two elements have the b. no two elements have the same atomic numbersame atomic number
2.2. Ex. C is 6, N is 7 and O is 8Ex. C is 6, N is 7 and O is 8
carbon nitrogen oxygencarbon nitrogen oxygen
III.III. Subatomic ParticlesSubatomic Particles B. Atomic Number and Mass B. Atomic Number and Mass NumberNumber
2. Mass number2. Mass numbera. the number of protons plus neutrons in a. the number of protons plus neutrons in
the nucleus of an atomthe nucleus of an atom
b. mass number is very close to the mass b. mass number is very close to the mass of an atom in of an atom in amu (atomic mass units)amu (atomic mass units)
c. two atoms with the same atomic c. two atoms with the same atomic number but different mass number are number but different mass number are called called isotopesisotopes
1) (mass #) – (atomic #) = #1) (mass #) – (atomic #) = #n n 00
III.III. Subatomic ParticlesSubatomic Particles
B. Atomic Number and Mass B. Atomic Number and Mass NumberNumber
1.1. Nuclear NotationNuclear Notation is one method is one method for depicting isotopes of an for depicting isotopes of an elementelement
2.2. contains the symbol of the contains the symbol of the element, the mass number, and element, the mass number, and the atomic numberthe atomic number
III.III. Subatomic ParticlesSubatomic Particles
C. Nuclear NotationC. Nuclear Notation
XMass number
Atomic
number
How many protons?How many protons? How many neutrons?How many neutrons? How many electrons?How many electrons?
III.III. Subatomic ParticlesSubatomic Particles
C. Nuclear NotationC. Nuclear Notation
Na
23
11
1. 1. Element symbol or nameElement symbol or name – – mass #mass #
2. 2. EXAMPLESEXAMPLES
a.a. Fluorine- Fluorine-1919
b.b. C- C-1414
c.c. U- U-238238
III.III. Subatomic ParticlesSubatomic Particles C. Hyphen NotationC. Hyphen Notation
1. Electrons and Ions1. Electrons and Ions a. For a. For neutral atomsneutral atoms, #, #ee-- = # = #pp++
b. If there are more electrons, a negative ion b. If there are more electrons, a negative ion
forms forms (anion)(anion)
c. If there are less electrons, a positive ion c. If there are less electrons, a positive ion
forms forms (cation)(cation)http://
www.youtube.com/watch?v=WWc3k2723IM
For now, we will work only with neutral atomsFor now, we will work only with neutral atoms
III.III. Subatomic Particles Subatomic Particles D. IonsD. Ions
The modern tableThe modern table Elements are still grouped by Elements are still grouped by
properties.properties. Similar properties are in the same Similar properties are in the same
column.column. Order is in increasing atomic number.Order is in increasing atomic number. Added a column of elements Added a column of elements
Mendeleev didn’t know about.Mendeleev didn’t know about. The noble gases weren’t found because The noble gases weren’t found because
they didn’t react with anything.they didn’t react with anything.
Trend of periodic tableTrend of periodic table
group1
group2
group13
group14
group15
group16
group17
group18
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar -
K Ca
group1
group2
group13
group14
group15
group16
group17
group18
21K 4K
1600K 2780K 2800K 4620K 77K 90K 85K 27K
1162K 1390K 2600K 2950K 553K 718K 239K 87K
1030K 1760K
Boiling point:
group1
group2
group13
group14
group15
group16
group17
group18
14K 0K
453K 1560K 2348K 3823K
63K 54K 53K 24K
379K 923K 933K 1687K
317K 388K 171K 83K
336K 1115K
Melting Point
Horizontal rows are called Horizontal rows are called periodsperiods
There are 7 periodsThere are 7 periods
1A
2A 3A 4A 5A 6A7A
8A0
The elements in the A groups are The elements in the A groups are called the called the representative elementsrepresentative elements
The The group B group B are called the are called the transition elementstransition elements
These are called the inner transition elements and they belong here
Group 1A are the alkali metalsGroup 1A are the alkali metals Group 2A are the alkaline earth Group 2A are the alkaline earth
metalsmetals
Group 7A is called the HalogensGroup 7A is called the Halogens Group 8A are the noble gasesGroup 8A are the noble gases
Subatomic Particles Subatomic Particles D. Formation of IonsD. Formation of Ions
Examples of IonsExamples of Ions
Atom loses electrons Atom gain Atom loses electrons Atom gain electronselectrons
and form cations and forms anionsand form cations and forms anions
Cations (+ ions)Cations (+ ions) Anions (- ions)Anions (- ions)
KK++ BrBr--
CaCa2+2+ OO2-2-
AlAl3+3+ NN3-3-
ionsions
D. Formation of Ions From D. Formation of Ions From AtomsAtoms
Na loses an electronNa loses an electron
and forms a cationand forms a cation
Na – eNa – e-- --> Na --> Na++
Cl gains an electronCl gains an electron
and forms an anionand forms an anion
Cl + eCl + e- - --> Cl--> Cl--
1.1. You You can never changecan never change the number of the number of
protonsprotons and have the same elementand have the same element
2.2. If you change the number of If you change the number of neutronsneutrons in in an atom, you get an an atom, you get an isotopeisotope
3.3. If you change the number of If you change the number of electronselectrons in an atom, you get an in an atom, you get an ionion
III.III. Subatomic Particles Subatomic Particles D. Changing Number of D. Changing Number of ParticlesParticles
IV.IV. Mass of AtomsMass of AtomsA. A. Atomic MassAtomic Mass
1. Mass of an atom1. Mass of an atom
a. too small to measure in gramsa. too small to measure in grams
b. use relative mass (amu)b. use relative mass (amu)
1) atomic mass unit1) atomic mass unit
2) 1 amu is defined as 1/12 the mass 2) 1 amu is defined as 1/12 the mass
of one C-12 atomof one C-12 atomhttp://
www.youtube.com/watch?feature=player_detailpage&v=nmjFKliv09E
1. weighted average mass of all known 1. weighted average mass of all known isotopesisotopes
aa. weighted means that the frequency . weighted means that the frequency of an isotope is consideredof an isotope is considered
b. mass of each isotope is multiplied byb. mass of each isotope is multiplied by
its percent occurrence in nature – its percent occurrence in nature – thenthen
masses of all isotopes is added to getmasses of all isotopes is added to get
the average atomic mass the average atomic mass
IV. Mass of AtomsIV. Mass of Atoms B. Average Atomic Mass B. Average Atomic Mass
IV. Mass of AtomsIV. Mass of Atoms C. The Mole and Molar Mass C. The Mole and Molar Mass1. measures the amount of substance1. measures the amount of substance
a. 1 a. 1 molemole = 6.02x10 = 6.02x1023 23 (Avogdro’s #) of (Avogdro’s #) of particles (atoms, molecules, ions, electrons)particles (atoms, molecules, ions, electrons) b. standard – 1mole is the number of atoms in b. standard – 1mole is the number of atoms in 12g of C-12 isotope12g of C-12 isotope2. 2. Molar massMolar mass – mass in grams of one mole – mass in grams of one mole (mol) of any substance(mol) of any substance a. numerically equal to atomic mass in amua. numerically equal to atomic mass in amu b. unit is grams/mol b. unit is grams/mol
Average Atomic MassAverage Atomic Mass
What is average atomic mass?What is average atomic mass?
Average atomic mass is the Average atomic mass is the weighted average of the atomic weighted average of the atomic masses of the naturally occurring masses of the naturally occurring isotopes of an elementisotopes of an element
Calculating a Weighted AverageCalculating a Weighted Average
ExampleExample
A box contains two size of marbles. IfA box contains two size of marbles. If
25.0% have masses of 2.00 g and 75.0%25.0% have masses of 2.00 g and 75.0%
have masses of 3.00 g what is the have masses of 3.00 g what is the weightedweighted
average?average?
(.250) (2.00) + (.750) (3.00) = .500 + 2.25 (.250) (2.00) + (.750) (3.00) = .500 + 2.25 ==
2.75g2.75g
Calculating Average Atomic Calculating Average Atomic MassMass
EXAMPLEEXAMPLE
Boron has two isotopes: Boron has two isotopes:
B-10 (mass 10.013 amu) 19.8% abundanceB-10 (mass 10.013 amu) 19.8% abundance
B-11 (mass 11.009 amu) 80.2% abundanceB-11 (mass 11.009 amu) 80.2% abundance
Calculate the average atomic mass.Calculate the average atomic mass.
(.198) (10.013) + (.802) ( 11.009) = (.198) (10.013) + (.802) ( 11.009) =
1.98 amu + 8.83 amu =1.98 amu + 8.83 amu = 10.81 10.81 amuamu
Calculating Average Atomic MassCalculating Average Atomic Mass
Calculate the average atomic mass of Mg.Calculate the average atomic mass of Mg.
Isotope 1 - 23.985 amu (78.99%)Isotope 1 - 23.985 amu (78.99%)
Isotope 2 - 24.986 amu (10.00%)Isotope 2 - 24.986 amu (10.00%)
Isotope 3 – 25.982 amu (11.01%)Isotope 3 – 25.982 amu (11.01%)
(23.985)(.7899)+(24.986)(.1000)+(25.982)(.1101)(23.985)(.7899)+(24.986)(.1000)+(25.982)(.1101)
18.95 amu + 2.498 amu + 2.861 amu =18.95 amu + 2.498 amu + 2.861 amu = 24.31 24.31 amuamu
Average Atomic MassAverage Atomic Mass
Helium has two naturally occurring Helium has two naturally occurring isotopes, He-3 and He-4. The atomic isotopes, He-3 and He-4. The atomic mass of helium is 4.003 amu. Which mass of helium is 4.003 amu. Which isotope is more abundant in nature?isotope is more abundant in nature?
He-4 is more abundant in nature He-4 is more abundant in nature because the atomic mass is closer to because the atomic mass is closer to the mass of He-4 than to the mass of the mass of He-4 than to the mass of He-3.He-3.
Calculating Average Atomic MassCalculating Average Atomic Mass
ProcessProcess1.1. Multiply %occurrence x mass of Multiply %occurrence x mass of
isotopeisotope2.2. Add products for each isotopeAdd products for each isotope isotope occurrence isotope occurrenceisotope occurrence isotope occurrence
Ex. X- 40 (30.0% ) X-30 (70.0%)Ex. X- 40 (30.0% ) X-30 (70.0%) (40 x .300) + (30 x .700) = (40 x .300) + (30 x .700) = 12 + 21 = 12 + 21 = 33 amu33 amu
Isotopic Pennies – number of pre and post Isotopic Pennies – number of pre and post 19821982a. Let X be the number of pre-1982 penniesa. Let X be the number of pre-1982 pennies
b. Let 10-X be the number of post-1982 penniesb. Let 10-X be the number of post-1982 pennies
c. (X)(3.1g) + (10-X)(2.5g) = mass of 10 pennies c. (X)(3.1g) + (10-X)(2.5g) = mass of 10 pennies pre-82 post-82pre-82 post-82
EXAMPLE (Mass of a sample of pennies is 31.0g)EXAMPLE (Mass of a sample of pennies is 31.0g)
(X)(3.1g) + [(10-X)(2.5g)] = 31.0 g(X)(3.1g) + [(10-X)(2.5g)] = 31.0 g
3.1X + 25 - 2.5X = 31.0g3.1X + 25 - 2.5X = 31.0g
.6X + 25 = 31.0g.6X + 25 = 31.0g
.6X = 6.0g X = 6.0g/.6 .6X = 6.0g X = 6.0g/.6
X =X = 10 pre-82 pennies 10 pre-82 pennies
10-X =10-X = 0 post-82 pennies0 post-82 pennies
Isotopic Penny Lab- Average Atomic MassIsotopic Penny Lab- Average Atomic Mass
Calculate percent of pre-82 and post-82 penniesCalculate percent of pre-82 and post-82 pennies
# of pre-82 pennies # of pre-82 pennies x 100% x 100% # post-82 pennies# post-82 pennies x x 100% 100%
10 1010 10
Calculate the average atomic mass of coiniumCalculate the average atomic mass of coinium
(% pre-82)(3.1g) + (% post-82)(2.5) = (% pre-82)(3.1g) + (% post-82)(2.5) = average atomic average atomic massmass
The MoleThe Mole
What is a mole in chemistry?What is a mole in chemistry?What conversion factors are What conversion factors are
associated with the mole?associated with the mole?Types of conversions Types of conversions
involvinginvolving mole equalities mole equalities
What is a Mole? What is a Mole? What are mole equalitiesWhat are mole equalities
A mole is equal to 6.02 x 10A mole is equal to 6.02 x 1023 23 particles particles Particles can be atoms, molecules or Particles can be atoms, molecules or
ionsions 6.02 x 106.02 x 102323 is Avogadro's Number is Avogadro's Number
Mole EqualitiesMole Equalities
- 1 mole = molar mass - 1 mole = molar mass
- 1 mole = 6.02 x 10- 1 mole = 6.02 x 102323 particles particles
Mole Conversions [mass-mole-Mole Conversions [mass-mole-atoms]atoms] Type Equality Used Type Equality Used1. MOLES 1. MOLES MASS MASS
2. MASS 2. MASS MOLES 1 mole= molar mass (g) MOLES 1 mole= molar mass (g)
3. MOLES 3. MOLES ATOMS ATOMS
4. ATOMS 4. ATOMS MOLES 1 mole = 6.02 x 10 MOLES 1 mole = 6.02 x 102323 atomsatoms
5. MASS 5. MASS ATOMS 1 mole = 6.02 x 10 ATOMS 1 mole = 6.02 x 102323 atomsatoms
6. ATOMS 6. ATOMS MASS 1 mole = molar mass (g)MASS 1 mole = molar mass (g)
Mole CalculationsMole CalculationsUsing Conversion FactorsUsing Conversion Factors
1 mole 1 mole molar mass molar mass
6.02 x 106.02 x 102323 1 mole 1 mole
PARTICLESPARTICLES <----> <----> MOLESMOLES <----> <----> MASSMASS
6.02 x 106.02 x 102323 1 mole1 mole
1 mole molar mass1 mole molar mass
Solving Mole ProblemsSolving Mole Problems
EXAMPLESEXAMPLES
1.1. 1.00 mole of He = 1.00 mole of He = 4.00 g.4.00 g.
2.2. 2.00 mole of He = _____g2.00 mole of He = _____g
2.00 mol He2.00 mol He X X 4.00g He 4.00g He = =
1 1 mole He1 1 mole He
8.00 g 8.00 g HeHe
EXAMPLESEXAMPLES
3.3. 1.00 mole He = 1.00 mole He = 6.02 X 106.02 X 102323 atoms atoms
4.4. 2.00 mole He = ________atoms He2.00 mole He = ________atoms He2.00 mole He2.00 mole He x x 6.02 x 106.02 x 102323 atoms He atoms He = = 12.04 x 10 12.04 x 102323
1 1 mole He1 1 mole He 1.20 x 101.20 x 102424
atoms Heatoms He5.5. 16.00g He = _____ moles He16.00g He = _____ moles He16.0 g He16.0 g He x x 1 mole He1 mole He = = 1 4.00 g He 1 4.00 g He 4.00 moles He4.00 moles He
EXAMPLESEXAMPLES
6.6. 3.01 X 103.01 X 102323 atoms He = _____ moles atoms He = _____ moles
3.01 x 103.01 x 102323 atoms He atoms He x x 1 mole He 1 mole He ==
1 6.02 x 101 6.02 x 102323 atoms He atoms He
.500 mol .500 mol HeHe
7.7. 8.00g He =______atoms He8.00g He =______atoms He
8.00 g He8.00 g He x x 1 mole He1 mole He x x 6.02 x 106.02 x 102323 atoms He atoms He = =
1 4.00g He 1 mole He 1 4.00g He 1 mole He
12.04 x 1012.04 x 102323 atoms He = atoms He = 1.20 x 101.20 x 102424 atoms He atoms He
Sample ProblemsSample Problems
1.1. Moles to massMoles to mass. . Find the mass of 3.50 moles of carbon. Find the mass of 3.50 moles of carbon. 2.2. Mass to MolesMass to Moles How many moles of carbon are How many moles of carbon are
contained incontained in 60.0 g of carbon? 60.0 g of carbon?
3.3. Moles to AtomsMoles to Atoms How many atoms of carbon are found in How many atoms of carbon are found in
4.00 moles of carbon?4.00 moles of carbon?
Sample ProblemsSample Problems4.4. Atoms to MolesAtoms to Moles How many moles of carbon are represented How many moles of carbon are represented
byby 1.806 x 101.806 x 102424 atoms of carbon? atoms of carbon?
5.5. Mass to AtomsMass to Atoms How many carbon atoms are found in 36.0g How many carbon atoms are found in 36.0g
of of carbon?carbon?
6.6. Atoms to MassAtoms to Mass What is the mass of 1.204 x 10What is the mass of 1.204 x 102424 atoms of atoms of
carbon?carbon?
More Sample ProblemsMore Sample Problems2.00 moles of Cu = atoms of Cu2.00 moles of Cu = atoms of Cu
60.0 grams of C = moles of C60.0 grams of C = moles of C
3.00 x 103.00 x 102323 atoms He = moles of He atoms He = moles of He
2.50 moles Al = grams of Al2.50 moles Al = grams of Al
28.0 grams N = atoms of N28.0 grams N = atoms of N
1.80 x 101.80 x 1023 23 atoms Mg = grams of Mgatoms Mg = grams of Mg
Mole CalculationsMole Calculations(Mass of Helium is 4.00 )(Mass of Helium is 4.00 )
11. 1.00 mole of helium = 4.00g. 1.00 mole of helium = 4.00g
2.2. 2.00 mole of helium = 8.00g2.00 mole of helium = 8.00g
3.3. 1.00 mole of helium = 6.02 x 101.00 mole of helium = 6.02 x 1023 23 atomsatoms
4.4. 2.00 mole of helium = 1.20 x 102.00 mole of helium = 1.20 x 102424 atoms atoms
5.5. 16.0g of helium = 4.00 mol16.0g of helium = 4.00 mol
6.6. 3.0l x 103.0l x 102323 atoms of helium = .500 moles atoms of helium = .500 moles
7.7. 8.00g of helium = 1.20 x 108.00g of helium = 1.20 x 102424 atoms. atoms.
