AP Ch 2 Atoms Molecules Ions Nomenclature
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Transcript of AP Ch 2 Atoms Molecules Ions Nomenclature
8/6/2019 AP Ch 2 Atoms Molecules Ions Nomenclature
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Atoms, Molecules and Ions
Chapter 2
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Dalton’s Atomic Theory (1808)
1. Elements are composed of extremely small
particles called atoms. All atoms of a givenelement are identical, having the same size,
mass and chemical properties. The atoms of one
element are different from the atoms of all other
elements.
2. Compounds are composed of atoms of more
than one element. The relative number of atoms
of each element in a given compound is alwaysthe same.
3. Chemical reactions only involve the rearrangement
of atoms. Atoms are not created or destroyed in
chemical reactions. 2.1
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2
2.1
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8 X2 Y16 X 8 Y+
2.1
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J.J. Thomson, measured mass/charge of e-
(1906 Nobel Prize in Physics) 2.2
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e- charge = -1.60 x 10-19 C
Thomson’s charge/mass of e- = -1.76 x 108 C/g
e- mass = 9.10 x 10-28 g
Measured mass of e-
(1923 Nobel Prize in Physics)
2.2
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Everybody Has Avogadro’sEverybody Has Avogadro’s
Number!Number!
But Where Did it Come From?But Where Did it Come From?• It was NOT just picked!
It was MEASURED.
• One of the better methods of measuring
this number was the
Millikan Oil Drop
Experiment
• Since then we have
found even better ways
of measuring using x-ray
technology
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(Uranium compound)
2.2
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2.2
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The modern view of the atom was developed byThe modern view of the atom was developed by ErnestErnestRutherfordRutherford (1871-1937).(1871-1937).
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1. atoms positive charge is concentrated in the nucleus
2. proton (p) has opposite (+) charge of electron (-)
3. mass of p is 1840 x mass of e- (1.67 x 10-24 g)
α particle velocity ~ 1.4 x 107 m/s
(~5% speed of light)
(1908 Nobel Prize in Chemistry)
2.2
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atomic radius ~ 100 pm = 1 x 10-10 m
nuclear radius ~ 5 x 10-3 pm = 5 x 10-15 m
Rutherford’s Model of
the Atom
2.2
“If the atom is the Houston Astrodome, then
the nucleus is a marble on the 50-yard line.”
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Chadwick’s Experiment (1932)
H atoms - 1 p; He atoms - 2 p
mass He/mass H should = 2
measured mass He/mass H = 4
α + 9Be 1n + 12 C + energy
neutron (n) is neutral (charge = 0)
n mass ~ p mass = 1.67 x 10-24 g2.2
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mass p = mass n = 1840 x mass e-
2.2
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Atomic number (Z) = number of protons in nucleus
Mass number (A) = number of protons + number of neutrons
= atomic number (Z) + number of neutrons
Isotopes are atoms of the same element (X) with different
numbers of neutrons in their nuclei
XAZ
H1
1H (D)
2
1H (T)
3
1
U23592 U238
92
Mass Number
Atomic Number Element Symbol
2.3
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2.3
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6 protons, 8 (14 - 6) neutrons, 6 electrons
6 protons, 5 (11 - 6) neutrons, 6 electrons
Do You Understand Isotopes?
2.3
How many protons, neutrons, and electrons are in C14
6 ?
How many protons, neutrons, and electrons are in C11
6 ?
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Period
G
roup
Alkali
Metal
NobleGas
Ha
logen
AlkaliEarth
Metal
2.4
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Chemistry In ActionNatural abundance of elements in Earth’s crust
Natural abundance of elements in human body
2.4
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A molecule is an aggregate of two or more atoms in a
definite arrangement held together by chemical bonds
H2
H2
O NH3
CH4
A diatomic molecule contains only two atoms
H2, N2, O2, Br 2, HCl, CO
A polyatomic molecule contains more than two atoms
O3, H2O, NH3, CH4
2.5
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ELEMENTSELEMENTS THAT EXIST THAT EXIST
ASAS
DIATOMICDIATOMIC
MOLECULESMOLECULES
ELEMENTSELEMENTS THAT EXIST THAT EXIST ASAS DIATOMICDIATOMIC MOLECULESMOLECULES
Remember:
BrINClHOF
These elementsonly exist as
PAIRS. Note that
when they
combine to make
compounds, they
are no longer
elements so they
are no longer in
pairs!
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An ion is an atom, or group of atoms, that has a net
positive or negative charge.
cation – ion with a positive chargeIf a neutral atom loses one or more electrons
it becomes a cation.
anion – ion with a negative charge
If a neutral atom gains one or more electronsit becomes an anion.
Na 11 protons11 electrons Na+ 11 protons
10 electrons
Cl17 protons
17 electrons Cl-17 protons
18 electrons
2.5
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Forming Cations & AnionsForming Cations & AnionsForming Cations & AnionsForming Cations & Anions
AA CATIONCATION formsforms
when an atomwhen an atom
loses one or loses one or
more electrons.more electrons.
AnAn ANIONANION formsforms
when an atomwhen an atom
gains one or gains one or
more electronsmore electrons
Mg --> Mg2+ + 2 e- F + e- --> F-
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A monatomic ion contains only one atom
A polyatomic ion contains more than one atom
2.5
Na+, Cl-, Ca2+ , O2- , Al3+ , N3-
OH-, CN-, NH4
+, NO3
-
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13 protons, 10 (13 – 3) electrons
34 protons, 36 (34 + 2) electrons
Do You Understand Ions?
2.5
How many protons and electrons are in ?Al2713
3+
How many protons and electrons are in ?Al7834
2-
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2.5
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2.6
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A molecular formula shows the exact number of
atoms of each element in the smallest unit of a
substance
An empirical formula shows the simplest
whole-number ratio of the atoms in a substance
H2OH2O
molecular empirical
C6H12 O6 CH2O
O3 O
N2H4 NH2
2.6
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ionic compounds consist of a combination of
cation(s) and an anion(s)
• the formula is always the same as the empirical formula• the sum of the charges on the cation(s) and anion(s) in each
formula unit must equal zero
The ionic compound NaCl
2.6
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Formula of Ionic Compounds
Al2O3
2.6
2 x +3 = +6 3 x -2 = -6
Al3+ O2-
CaBr 2
1 x +2 = +2 2 x -1 = -2
Ca2+ Br -
Na2CO3
1 x +2 = +2 1 x -2 = -2
Na+ CO32-
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2.6
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2.7
l f ld f i
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Examples of Older Names of Cations
formed from Transition Metals
(memorize these!!)From Zumdahl
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Chemical Nomenclature
• Ionic Compounds – often a metal + nonmetal
– anion (nonmetal), add “ide” to element name
BaCl2 barium chloride
K2O potassium oxide
Mg(OH)2 magnesium hydroxide
KNO3 potassium nitrate
2.7
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• Transition metal ionic compounds
– indicate charge on metal with Roman numerals
FeCl2 2 Cl- -2 so Fe is +2 iron(II) chloride
FeCl3 3 Cl- -3 so Fe is +3 iron(III) chloride
Cr 2S3 3 S-2 -6 so Cr is +3 (6/2) chromium(III) sulfide
2.7
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• Molecular compounds
• nonmetals or nonmetals + metalloids
• common names
• H2O, NH
3, CH
4, C
60
• element further left in periodic table
is 1st
•element closest to bottom of group is1st
• if more than one compound can be
formed from the same elements, use
prefixes to indicate number of each
kind of atom
• last element ends in ide
2.7
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HI hydrogen iodide
NF3 nitrogen trifluoride
SO2 sulfur dioxide
N2Cl4 dinitrogen tetrachloride
NO2 nitrogen dioxide
N2O dinitrogen monoxide
Molecular Compounds
2.7
TOXIC!
Laughing Gas
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2.7
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An acid can be defined as a substance that yields
hydrogen ions (H+) when dissolved in water.
HCl•Pure substance, hydrogen chloride•Dissolved in water (H+ Cl-), hydrochloric acid
An oxoacid is an acid that contains hydrogen,
oxygen, and another element.
HNO3
nitric acid
H2CO3 carbonic acid
H2SO4 sulfuric acid
2.7HNO3
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2.7
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2.7
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2.7
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2.7
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Mixed Practice
1. Dinitrogen monoxide
2. Potassium sulfide
3. Copper (II) nitrate4. Dichlorine heptoxide
5. Chromium (III) sulfate
6. Ferric sulfite7. Calcium oxide
8. Barium carbonate
9. Iodine monochloride
1. N2O
2. K2S
3. Cu(NO3)2
4. Cl2O7
5. Cr 2(SO4)3
6. Fe2(SO3)3
7. CaO
8. BaCO3
9. ICl
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Mixed Practice
1.1. BaIBaI22
2.2. PP44SS33
3.3. Ca(OH)Ca(OH)22
4.4. FeCOFeCO33
5.5. Na Na22Cr Cr
22OO77
6.6. II22
OO55
7.7. Cu(ClOCu(ClO44))22
8.8. CSCS22
9.9. BB22ClCl44
1.1. Barium iodideBarium iodide
2.2. Tetraphosphorus trisulfideTetraphosphorus trisulfide
3.3. Calcium hydroxideCalcium hydroxide4.4. Iron (II) carbonateIron (II) carbonate
5.5. Sodium dichromateSodium dichromate
6.6. Diiodine pentoxideDiiodine pentoxide
7.7. Cupric perchlorateCupric perchlorate
8.8. Carbon disulfideCarbon disulfide
9.9. Diboron tetrachlorideDiboron tetrachloride