the atom atomic number and mass number isotopes

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1 The Atom Atomic Number and Mass Number Isotopes

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The Atom Atomic Number and Mass Number Isotopes. Atomic Theory. Atoms are building blocks of elements Similar atoms in each element Different from atoms of other elements Two or more different atoms bond in simple ratios to form compounds. Subatomic Particles. - PowerPoint PPT Presentation

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Page 1: The Atom Atomic Number and Mass Number Isotopes

11

The Atom

Atomic Number and Mass Number

Isotopes

Page 2: The Atom Atomic Number and Mass Number Isotopes

22

Atomic TheoryAtomic Theory

Atoms are building blocks of elements

Similar atoms in each element

Different from atoms of other elements

Two or more different atoms bond in simple

ratios to form compounds

Page 3: The Atom Atomic Number and Mass Number Isotopes

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Subatomic ParticlesSubatomic Particles

Particle Symbol Charge RelativeMass

Electron e- 1- 0

Proton p+ + 1

Neutron n 0 1

Page 4: The Atom Atomic Number and Mass Number Isotopes

44

Location of Subatomic ParticlesLocation of Subatomic Particles

10-13 cm

electrons

protons

neutrons

10-8 cm

nucleus

Page 5: The Atom Atomic Number and Mass Number Isotopes

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Atomic NumberAtomic Number

Counts the number

of

protons

in an atom

Page 6: The Atom Atomic Number and Mass Number Isotopes

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Periodic TablePeriodic Table

Represents physical and chemical behavior

of elements

Arranges elements by increasing atomic

number

Repeats similar properties in columns known

as chemical families or groups

Page 7: The Atom Atomic Number and Mass Number Isotopes

77

Periodic TablePeriodic Table

1 2 3 4 5 6 7 8

11 Na

Page 8: The Atom Atomic Number and Mass Number Isotopes

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Atomic Number on the Periodic Atomic Number on the Periodic TableTable

11

Na

Atomic Number

Symbol

Page 9: The Atom Atomic Number and Mass Number Isotopes

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All atoms of an element have All atoms of an element have the same number of protonsthe same number of protons

11

Na

11 protons

Sodium

Page 10: The Atom Atomic Number and Mass Number Isotopes

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Learning Check AT 1Learning Check AT 1

State the number of protons for atoms of each of the following:

A. Nitrogen

1) 5 protons 2) 7 protons 3) 14 protons

B. Sulfur

1) 32 protons 2) 16 protons 3) 6 protons

C. Barium

1) 137 protons 2) 81 protons 3) 56 protons

Page 11: The Atom Atomic Number and Mass Number Isotopes

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Solution AT 1Solution AT 1

State the number of protons for atoms of each of the following:

A. Nitrogen

2) 7 protons

B. Sulfur

2) 16 protons

C. Barium

3) 56 protons

Page 12: The Atom Atomic Number and Mass Number Isotopes

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Number of ElectronsNumber of Electrons

An atom is neutral The net charge is zeroNumber of protons = Number of electronsAtomic number = Number of electrons

Page 13: The Atom Atomic Number and Mass Number Isotopes

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Mass NumberMass Number

Counts the number

of

protons and neutrons

in an atom

Page 14: The Atom Atomic Number and Mass Number Isotopes

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Atomic SymbolsAtomic Symbols

Show the mass number and atomic number

Give the symbol of the element

mass number

23 Na sodium-23

atomic number 11

Page 15: The Atom Atomic Number and Mass Number Isotopes

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More Atomic SymbolsMore Atomic Symbols

16 31 65

O P Zn 8 15 30

8 p+ 15 p+ 30 p+

8 n 16 n 35 n

8 e- 15 e- 30 e-

Page 16: The Atom Atomic Number and Mass Number Isotopes

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IsotopesIsotopes

Atoms with the same number of protons,

but different numbers of neutrons.

Atoms of the same element (same atomic

number) with different mass numbers

Isotopes of chlorine

35Cl 37Cl17 17

chlorine - 35 chlorine - 37

Page 17: The Atom Atomic Number and Mass Number Isotopes

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Questions 2Questions 2

Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of these carbon atoms.

12C 13C 14C 6 6 6

#P _______ _______ _______

#N _______ _______ _______

#E _______ _______ _______

Page 18: The Atom Atomic Number and Mass Number Isotopes

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Solutions 2Solutions 2

12C 13C 14C 6 6 6

#P __6___ _ 6___ ___6___

#N __6___ _ _7___ ___8___

#E __6___ _ 6___ ___6___

Page 19: The Atom Atomic Number and Mass Number Isotopes

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Questions 3Questions 3

An atom of zinc has a mass number of 65.

A. Number of protons in the zinc atom

1) 30 2) 35 3) 65

B. Number of neutrons in the zinc atom

1) 30 2) 35 3) 65

C. What is the mass number of a zinc isotope

with 37 neutrons?

1) 37 2) 65 3) 67

Page 20: The Atom Atomic Number and Mass Number Isotopes

2020

Solutions 3Solutions 3

An atom of zinc has a mass number of 65.

A. Number of protons in the zinc atom

1) 30

B. Number of neutrons in the zinc atom

2) 35

C. What is the mass number of a zinc isotope

with 37 neutrons?

3) 67

Page 21: The Atom Atomic Number and Mass Number Isotopes

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Questions 4Questions 4

Write the atomic symbols for atoms with the following:

A. 8 p+, 8 n, 8 e- ___________

B. 17p+, 20n, 17e- ___________

C. 47p+, 60 n, 47 e- ___________

Page 22: The Atom Atomic Number and Mass Number Isotopes

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Solutions 4Solutions 4

16OA. 8 p+, 8 n, 8 e- 8

B. 17p+, 20n, 17e- 37Cl 17

C. 47p+, 60 n, 47 e- 107Ag 47

Page 23: The Atom Atomic Number and Mass Number Isotopes

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Questions 5Questions 5

An atom has 14 protons and 20 neutrons.A. Its atomic number is

1) 14 2) 16 3) 34

B. Its mass number is1) 14 2) 16 3) 34

C. The element is1) Si 2) Ca 3) Se

D. Another isotope of this element is

1) 34X 2) 34X 3) 36X 16 14 14

Page 24: The Atom Atomic Number and Mass Number Isotopes

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Solutions 5Solutions 5

An atom has 14 protons and 20 neutrons.A. It has atomic number

1) 14

B. It has a mass number of3) 34

C. The element is1) Si

D. Another isotope of this element would be

3) 36X 14

Page 25: The Atom Atomic Number and Mass Number Isotopes

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Masses of AtomsMasses of Atoms

A scale designed for atoms gives their small

atomic masses in atomic mass units (amu)

An atom of 12C was assigned an exact mass of

12.00 amu

Relative masses of all other atoms was

determined by comparing each to the mass of 12C

An atom twice as heavy has a mass of 24.00

amu. An atom half as heavy is 6.00 amu.

Page 26: The Atom Atomic Number and Mass Number Isotopes

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Atomic MassAtomic Mass

Listed on the periodic table

Gives the mass of “average” atom of each

element compared to 12C

Average atom based on all the isotopes and their

abundance %

Atomic mass is not a whole number

Na22.99

Page 27: The Atom Atomic Number and Mass Number Isotopes

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Questions 6Questions 6

Using the periodic table, specify the atomic mass of each element (round to the tenths place):

A. calcium __________

B. aluminum __________

C. lead __________

D. barium __________

E. iron __________

Page 28: The Atom Atomic Number and Mass Number Isotopes

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Solution AT6Solution AT6

Using the periodic table, specify the atomic mass of each element (round to the tenths place):

A. calcium _40.1 amu _

B. aluminum _27.0 amu _

C. lead _207.2 amu_

D. barium _137.3 amu_

E. iron _55.8 amu__

Page 29: The Atom Atomic Number and Mass Number Isotopes

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Calculating Atomic MassCalculating Atomic Mass

Percentage (%) abundance of isotopes

Mass of each isotope of that element

Weighted average =

mass isotope1(%) + mass isotope2(%) + …

100 100

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Atomic Mass of MagnesiumAtomic Mass of Magnesium

Isotopes Mass of Isotope Abundance 24Mg = 24.0 amu 78.70%

25Mg = 25.0 amu 10.13%

26Mg = 26.0 amu 11.17%

Atomic mass (average mass) Mg = 24.3 amu

Mg24.3

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Questions 7Questions 7

Gallium is a metallic element found in

small lasers used in compact disc players.

In a sample of gallium, there is 60.2% of

gallium-69 (68.9 amu) atoms and 39.8% of

gallium-71 (70.9 amu) atoms. What is the

atomic mass of gallium?

Page 32: The Atom Atomic Number and Mass Number Isotopes

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Solutions 7Solutions 7

Ga-69

68.9 amu x 60.2 = 41.5 amu for 69Ga

100

Ga-71 (%/100)

70.9 amu x 39.8 = 28.2 amu for 71Ga

100

Atomic mass Ga = 69.7 amu

Page 33: The Atom Atomic Number and Mass Number Isotopes

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Finding An Isotopic MassFinding An Isotopic Mass

A sample of boron consists of 10B (mass 10.0 amu) and 11B (mass 11.0 amu). If the average atomic mass of B is 10.8 amu, what is the % abundance of each boron isotope?

Page 34: The Atom Atomic Number and Mass Number Isotopes

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Assign X and Y values:X = % 10B Y = % 11B

Determine Y in terms of XX + Y = 100Y = 100 - X

Solve for X:X (10.0) + (100 - X )(11.0) = 10.8

100 100

Multiply through by 10010.0 X + 1100 - 11.0X = 1080

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Collect X terms

10.0 X - 11.0 X = 1080 - 1100

- 1.0 X = -20

X = -20 = 20 % 10B

- 1.0

Y = 100 - X

% 11B = 100 - 20% = 80% 11B

Page 36: The Atom Atomic Number and Mass Number Isotopes

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Questions 8Questions 8

Copper has two isotopes 63Cu (62.9 amu) and 65Cu (64.9 amu). What is the % abundance of each isotope? (Hint: Check periodic table for atomic mass)

1) 30% 2) 70% 3) 100%

Page 37: The Atom Atomic Number and Mass Number Isotopes

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Solutions 8Solutions 8

2) 70%

Solution

62.9X + 6490 = 64.9X = 6350

-2.0 X = -140

X = 70%