View
267
Download
0
Category
Tags:
Preview:
Citation preview
The Atom
Essential Question?
Compare and contrast the characteristics of an atom and function of these
characteristics in an atom?
Structure of an Atom
Atom
Proton(p+)
Neutron(no)
Electron(e-)
Protonp+
• Positive Charge (p+)
• Located in the nucleus
• Mass of a proton = 1.673 x 10-24g • Relative Mass 1 amu
• Function: Gives an atom its identity – If the # of protons changes so does the type of atom
Ex: Hydrogen has 1 proton Helium has 2 protons Lithium has 3 protons
• The Atomic # always equals the # of protons
Ex: Hydrogen has an Atomic # = 1 and has 1 proton
Proton
Neutronno
• No charge
• Located in the nucleus
• Mass of a neutron 1.675 x 10-24g• Relative Mass = 1 amu• Function: Adds mass to nucleus
• Mass # - Atomic # = # of no
Ex: 1-1=0 hydrogen has 0 no
Neutron
Electrone-
• Negative charge
• Has very small mass (9.109 x 10-28g) and is not included in the atomic mass of the atom
• Relative Mass = 1/1840
• Located outside the nucleus- electron cloud- orbitals- shells- energy levels
Ex: Hydrogen has 1e-
• Function: Is responsible for an atoms behavior
Electron
• Atomic # = # protons = # electrons– Which element has 32 protons? Symbol__ Name __– Which element has 14 protons? Symbol__ Name __
• The mass number is the number of protons PLUS the number of neutrons in an atom.
• This is because the mass of the atom is mainly inside the nucleus where the protons and neutrons are found.
• The mass number – protons = number of neutrons on the Periodic Table
Find and Round the Atomic Mass to the nearest whole number
Element Symbol Average Atomic Mass
Mass Number
(round # up or down)
Ca
Barium
Cl
Nickel
Find and Round the Atomic Mass to the nearest whole number
Element Symbol Average Atomic Mass
Mass Number
(round # up or down)
Calcium Ca 40.1 amu 40 amu
Barium Ba 137.3 amu 137 amu
Chlorine Cl 35.5 amu 36 amu
Nickel Ni 58.7 amu 59 amu
Three types of atoms
Atoms can be an
Element Ion Isotope
This will help you determine which type of atom you have
• If the p+ ≠ e- then you have an ION
• If you add the p+ + no & the mass # ≠ the mass on the PT, you have an ISOTOPE
• If the mass # = the mass # on the PT, and the p+ = e- then you have an Element
Element• Cannot be broken down into simpler substances by physical or chemical
means
• Each has a symbol located on the Periodic TableEx: Ag – Silver, Pb – Lead
• Each has an atomic # and atomic massEx: Ag – Atomic # = 47
Atomic mass = 107.9 amuPb – Atomic # = 82
Atomic mass = 207.2 amu
• Atomic # = # of p+ = # of e-
• If the # of p+ = the # of e- the atom is electrically neutral
• Atomic mass = # of p+ + # of no (this number must match the rounded atomic mass (or Mass #) on the periodic table)
Element - Fill in the table belowElement Atomic # Protons Neutrons Electrons Mass #
H
He
Li
Be
B
C
N
O
F
Ne
ElementFill in the table below
Element Atomic # Protons Neutrons Electrons Mass #
H 1 1 0 1 1
He 2 2 2 2 4
Li 3 3 4 3 7
Be 4 4 5 4 9
B 5 5 6 5 11
C 6 6 6 6 12
N 7 7 7 7 14
O 8 8 8 8 16
F 9 9 10 9 19
Ne 10 10 10 10 20
Ion• An ion is an atom with a charge. The charge is either positive
or negative
• The charge depends on if the electrons are donated (lost) or accepted (gained)
Ex: If an atom donates e- then the charge becomes positive (+)
Na+
Ex: If an atom accepts e- then the charge becomes negative (-)
Cl-
• To identify an ion the # of protons will NOT equal the # of electrons
Ex: Cl normally has 17e-
A Cl- ion has 18e- (Cl has accepted 1e-)
Ion - Fill in the table belowElement Protons Electrons Gained or
Lost e-?
H 0
Li 2
Be 2
B 2
N 8
O 9
F 10
Ion - Fill in the table belowElement Protons Electrons Gained or
Lost e-?
H 1 0 Lost
Li 3 2 Lost
Be 4 2 Lost
B 5 2 Lost
N 7 8 Gained
O 8 9 Gained
F 9 10 Gained
Are the number of protons and electrons the same or different? DIFFERENT
Isotopes• Are atoms with the same number of protons but has a different
number of neutrons than the normal number of neutrons in an atom
• To calculate the # of no round the atomic mass to the nearest whole number then subtract the atomic number.
• When the atomic mass is rounded it is called the Mass number Mass number – Atomic number = # of no
Ex: (Pb) 207 – 82 = 125 neutrons
• If the atom is an isotope then there will be more neutrons and the mass will be more
Ex: (Pb) 208 – 82 = 126 neutrons
• Isotopes are neutron rich and unstable
Isotopic Notation
Ex: Silicon
Si28
14
Mass #
Atomic #
Isotopic Name
Silicon-28Mass #
Let’s Compare the Following
Carbon-12 Carbon-13 Carbon-14
Atomic #
Protons
Electrons
Mass Number
Neutrons
Let’s Compare the Following
Carbon-12 Carbon-13 Carbon-14
Atomic # 6 6 6
Protons 6 6 6
Electrons 6 6 6
Mass Number 12 13 14
Neutrons 6 7 8
How are the notations alike?
How are the above notations different?
Same protons and electrons
Different Mass # & neutrons
ReviewIsotopes are atoms of the same element with the same number of _______, but with different numbers of _______.
Answer questions 1-5 in Part I
Answer questions 6-10 in Part II
Complete Isotopes or Different Elements WS
Front and back# Statement Element(s) Different Element,
Isotope
1 Element D has 6 protons and 6 neutrons
Element F has 7 protons and 7 neutrons
2 Element J has 27 protons and 32 neutrons
Element L has 27 protons and 33 neutrons
3 Element X has 17 protons and 18 neutrons
Element Y has 18 protons and 17 neutrons
4 Element Q has 56 protons and 81 neutrons
Element R has 56 protons and 82 neutrons
5 Element T has an atomic # of 20 and an atomic mass of 40
Element Z has an atomic # of 20 and an atomic mass of 41
6 Element W has 8 protons and 8 neutrons
Element V has 7 protons and 8 neutrons
7 Element P has an atomic # of 92 and an atomic mass of 238
Element S has an atomic # of 92 and an 143 neutrons
Complete Isotopes or Different Elements WS
Front and back# Statement Element(s) Different Element,
Isotope
1 Element D has 6 protons and 6 neutrons
Element F has 7 protons and 7 neutrons
Carbon
Nitrogen
DE
2 Element J has 27 protons and 32 neutrons
Element L has 27 protons and 33 neutrons
Cobalt - 59
Cobalt - 60
Isotope
3 Element X has 17 protons and 18 neutrons
Element Y has 18 protons and 22 neutrons
Chlorine
Argone
DE
4 Element Q has 56 protons and 81 neutrons
Element R has 56 protons and 82 neutrons
Barium - 137
Barium - 138
Isotope
5 Element T has an atomic # of 20 and an atomic mass of 40
Element Z has an atomic # of 20 and an atomic mass of 41
Calcium - 40
Calcium - 41
Isotope
6 Element W has 8 protons and 8 neutrons
Element V has 7 protons and 7 neutrons
Oxygen
Nitrogen
DE
7 Element P has an atomic # of 92 and an atomic mass of 238
Element S has an atomic # of 92 and an 143 neutrons
Uranium - 238
Uranium - 235
Isotope
Element Symbol Atomic # Mass # # of p+ # of no # of e-
Helium
24
30 31
Br
13
U
11 12
Krypton
Ca
Ag 61
Fill in the Chart Below
Element Symbol Atomic # Mass # # of p+ # of no # of e-
Helium He 2 4 2 2 2
Magnesium Mg 12 24 12 12 12
Zinc Zn 30 65 30 35 31
Bromine Br 35 80 35 45 35
Aluminum Al 13 27 13 14 13
Uranium U 92 238 92 146 92
Sodium Na 11 23 11 12 12
Krypton Kr 36 84 36 48 36
Calcium Ca 20 40 20 20 20
Silver Ag 47 108 47 61 47
Fill in the Chart Below
Summarize
• Fill in Part V chart
Isotopic Notation
Isotopic Name
Atomic # # of p+ # of no # of e- Mass #
Zinc-67
17 36
Lead-207
99 155
94 244
Thallium-210
Fill in the Chart Below
Br8035
Fm260100
Isotopic Notation
Isotopic Name
Atomic # # of p+ # of no # of e- Mass #
80 205
78 200
Tungsten-191
79 112
Fill in the Chart Below
Fr23287
Isotopic Notation
Isotopic Name
Atomic # # of p+ # of no # of e- Mass #
Bromine-80 35 35 45 35 80
Zinc-67 30 30 37 30 67
Chlorine-53 17 17 36 17 53
Lead-207 82 82 125 82 207
Einsteinium-155
99 99 56 99 155
Plutonium-244 94 94 150 94 244
Fermium-260 100 100 160 100 260
Thallium-210 81 81 129 81 210
Fill in the Chart Below
Zn6730
Br8035
Fm260100
Cl5317
Pb20782
Es15599
Pu24494
Tl21081
Isotopic Notation
Isotopic Name
Atomic # # of p+ # of no # of e- Mass #
Mercury-205 80 80 125 80 205
Francium-232 87 87 145 87 232
Platinum-200 78 78 122 78 200
Tungsten-191 74 74 117 74 191
Gold-112 79 79 33 79 112
Fill in the Chart Below
Fr23287
Hg20580
Pt20078
W19174
Au11279
Summarize
• Answer questions part VI
Part VII Potassium
• K – 39 has 20 neutrons
• K – 40 has 21 neutrons
• K – 41 has 22 neutrons
K3919
K4019
K4119
Atomic Mass Determination
• Chemist have developed a method of measuring mass of an atom called:
Atomic Mass DeterminationUnit is abbreviated “amu”
• They did this because the masses of subatomic particles are so small that even scientific notation makes it hard to calculate the masses of elements.
• The atomic mass that you see on the PT is the average mass for the isotopes of that element.
• The atomic mass you see on the PT is also the isotope that is most abundant in nature!!!
• Answer Question 1 & 2
How is Atomic Mass Calculated?
• The mass on the Periodic Table is the average mass of the isotopes of an atom
• To determine the atomic mass of an atom use this formula
(Mass (amu) x Percent abundance)= Isotope A (Mass (amu) x Percent abundance)= Isotope B
Add A + B / 100 = atomic mass
Example Problem #1• Calculate the atomic mass of the unknown
element. Then identify the element using the Periodic Table?
IsotopeIsotopic Notation
Mass (amu) Percent Abundance
185X 184.953 37.40 187X 186.956 62.60
(184.953 amu x 37.40) = 6917.35 amu(186.956 amu x 62.60) = 11703.45 amu
6917.35 amu trace/least abundant
+11703.45 amu most abundant
18620.8 / 100 = 186.2 amu
Rhenium = Re
Practice Problem #2
• Calculate the atomic mass of the unknown element. Then identify the element?
IsotopeIsotopic Notation
Mass (amu) Percent Abundance
113X 112.904 __?__
115X 114.904 95.70
Which Isotope is trace and which is more abundant?
(112.904 amu x 4.30 ) = 485 amu(114.904 amu x 95.70) = 10996.3128 amu
485 amu trace/least abundant
+10996.3128 amu most abundant
11481.3128 / 100 = 114.81 amu
Indium = In
Practice Problems (Book)
• Pp. 104 15-17#15 Boron has 2 naturally occurring isotopes: boron-10(abundance =
19.8%, mass = 10.013 amu), boron-11 (abundance = 80.2 %, mass = 11.009 amu) Calculate the atomic mass of boron.
#16 Helium has 2 naturally occurring isotopes, helium-3 and helium-4. The atomic mass of helium is 4.003 amu. Which isotope is more abundant in nature? Explain
#17 Calculate the atomic mass of magnesium. The three magnesium isotopes have atomic masses and relative abundances of 23.995 amu (78.99%), 24.986 amu (10.00%), 25.982 amu (11.01%).
Practice Problem #1
Answer = 10.81 amu
IsotopeIsotopic notation
Mass (amu) Percent Abundance
10B 10.013 19.8 11B 11.009 80.2 5
5
Practice Problem #2
Answer = 107.9 amu
IsotopeIsotopic Notation
Mass (amu) Percent Abundance
107Ag 106.9 51.82 109Ag 108.9 48.18 47
47
Practice Problem #3
Answer = 24.31 amu
IsotopeIsotopic Notation
Mass (amu) Percent Abundance
24Mg 23.985 78.9925Mg 24.986 10.0026Mg 25.982 11.01
12
12
12
Practice Problem #4
Helium-4 is most abundant b/c its mass is closer to the average atomic mass on the PT
Helium-3 mass is not as close as Helium-4, so Helium-3 is less abundant
Practice Problem #5
Answer = 20.19 amu
IsotopeIsotopic Notation
Mass (amu) Percent Abundance
20Ne 19.992 9022Ne 21.991 1010
10
Practice Problem #6
Answer = 178.55 amu
IsotopeIsotopic Notation
Mass (amu) Percent Abundance
176Hf 176 5.00
177Hf 177 19.0
178Hf 178 27.0179Hf 179 14.0
180Hf 180 35.0
72
72
72
72
72
Practice Problem #7
Answer = 28.09 amu
IsotopeIsotopic Notation
Mass (amu) Percent Abundance
28Si 27.977 92.2129Si 28.976 4.7030Si 29.975 3.09
14
14
14
Practice Problem #8
Answer = 107.87 amu
IsotopeIsotopic Notation
Mass (amu) Percent Abundance
107Ag 106.905 51.83108Ag 108.905 48.1747
47
Practice Problem #9
Answer = Neon-20 Why? Its mass is closest to the average mass of neon on the PT.
IsotopeIsotopic Name
Atomic # Mass (amu)
Neon-20 10 19.992
Neon-21 10 20.994
Neon-22 10 21.991
Practice Problem #10
Answer = 83.80 amu
IsotopeIsotopic Notation
Mass (amu) Percent Abundance
78Kr 77.920 0.350
80Kr 79.916 2.27
82Kr 81.913 11.5683Kr 82.914 11.55
84Kr 83.912 56.90
86Kr 85.911 17.37
36
36
36
36
36
36
How was the Atom Discovered?
• Fill in Atomic Theory WS
• Use your book
Many early philosophers thought matter was
made up of 4 components
Earth – Air, Fire – Water
Democritus’s Ideas(384-322 B.C.)
• Matter is composed of empty space through which atoms move
• Atoms are solid homogenous, indestructible & indivisible
• Different kinds of atoms have different sizes & shapes
• The differing properties of matter are due to the size, shape and movement of atoms
• Apparent changes in matter result from changes in the grouping of atoms and not from the changes in atoms themselves
Dalton’s Ideas(1766-1844)
• All matter is composed of extremely small particles called atoms
• All atoms of a given element are identical, having the same size, mass and chemical properties. Atoms of a specific element are different than those of any other element.
• Atoms cannot be created, divided into smaller particles or destroyed.
• Different atoms combine in simple whole ratios to form compounds
• In a chemical reaction, atoms are separated, combined or rearanged.
Mendeleev’s Contribution
• Developed the Periodic Table
• Arranged the Periodic Table based on atomic mass
Roentgen’s Discovery
• X-Rays – invisible rays of e- bombarding the surface of materials
• Noticed this mysterious radiation passed through soft tissue, but not bone or metals
Currie’s Discovery
• Radioactivity – radiation
• Found Polonium, Radium
Bacquerel’s Contribution
• Phosphorescent minerals – uranium salts exposed photographic plates in dark
• Found that uranium naturally emits radiation
J. J. Thomson’s Discovery
• Determine the mass ratio of particles
• Said Dalton was wrong
• Found e-
Thompson’s Concept of the Atom
• Plum Pudding Model
• Negatively charged electrons were distributed throughout a uniform positive charge
Cathode Ray ExperimentWilliam Crookes – Accidentally found
Lead to the invention of the TV, Computer monitors(Radiation hits light producing chemicals on the backsides of screens)
• Vacuum tube – gas @ low pressure – Electric charge (-) cathode passes to (+) anode – light is electrons
• React to magnets
• Light is a stream of charged particles
• Particles have a (-) charge
Found a particle smaller than the H atom by looking at known charge to mass ratios.
WS – Cathode Ray Experiments
Rutherford’s Contribution(1871-1937)
• Found Nucleus
• Nucleus has a (+) charge
• Devised a way with H. G. Moseley to bombard elements with a cathode ray which they used to assign atomic numbers to elements
• Found - Alpha, Beta, Gamma radiation
Rutherford’s Gold Foil Experiment
• Narrow beam of alpha particles was aimed @ a thin sheet of gold foil. Zinc sulfide screen surrounding the gold foil produced a flash of light whenever it was struck by an alpha particle
WS – Understanding Rutherford’s Gold Foil Experiment
•The deflection was the alpha particle bouncing off the nucleus
Bohr’s Contribution(1885-1962)
• Model of an atom
• Small orbit = lower energy state or energy level
• Part of the Manhattan
Project
• Advocate for safe use of
Atomic energy
Chadwick’s Discovery
• Neutron
• No Charge
• Mass almost = to mass of proton
Definitions
• Atomic Mass – total average mass of an atom• Atomic number - # of p+, in an atom• Mass Number – total # of p+, & no
• Atom – Smallest particle in an element, electrically neutral, spherically shaped and composed of p+, no and e-
• Ion – An atom or bonded group of atoms w/ a (+) or (-) charge.
• Isotope – atoms of the same element w/ different # of no
Element Symbol Element, Ion,
Isotope
Atomic # Mass # Protons neutrons electrons
B
Sulfur
7
Chlorine 18
Carbon-14
31 15
13 15
Iodine-128
22 18
Complete the Following Table
Element Symbol Element, Ion,
Isotope
Atomic # Mass # Protons neutrons electrons
Boron B E 5 11 5 6 5
Sulfur S E 16 32 16 16 16
Nitrogen N E 7 14 7 7 7
Chlorine Cl Ion 17 35 17 18 18
Carbon-14 C-14 Isot 6 14 6 8 6
Phosphorus P E 15 31 15 16 15
Aluminum Al Isot 13 28 13 15 13
Iodine-128 I-128 Iso 53 128 53 75 53
Argon Ar E 18 40 18 22 18
Complete the Following Table
Recommended