Atomos: Not to Be CutAtomos: Not to Be Cut

Chapter 5 Lesson 1Chapter 5 Lesson 1

22

Atomic TheoryAtomic Theory

Atoms are building blocks of elements Atoms are building blocks of elements

Similar atoms in each elementSimilar atoms in each element

Different from atoms of other elementsDifferent from atoms of other elements

Two or more different atoms bond in simple Two or more different atoms bond in simple

ratios to form compoundsratios to form compounds

33

Subatomic ParticlesSubatomic Particles

ParticleParticle Symbol Symbol Charge Charge RelativeRelativeMassMass

ElectronElectron e e-- 1-1- 0 0

ProtonProton p p++ + + 1 1

NeutronNeutron n n 0 0 1 1

44

Location of Subatomic ParticlesLocation of Subatomic Particles

1010-13 -13 cmcm

electronselectrons

protonsprotons

neutronsneutrons

1010-8 -8 cmcm

nucleus

55

Atomic NumberAtomic Number

Counts the numberCounts the number

of of

protonsprotons

in an atomin an atom

66

Periodic TablePeriodic Table

Represents physical and chemical behavior Represents physical and chemical behavior

of elementsof elements

Arranges elements by increasing atomic Arranges elements by increasing atomic

numbernumber

Repeats similar properties in columns known Repeats similar properties in columns known

as chemical families or groupsas chemical families or groups

77

Periodic TablePeriodic Table

11 2 2 3 4 5 6 7 3 4 5 6 7 88

11 Na

88

Atomic Number on the Periodic Atomic Number on the Periodic TableTable

1111

NaNa

Atomic Number

Symbol

99

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

1111

NaNa

11 protons

Sodium

1010

Learning Check AT 1Learning Check AT 1

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

A. Nitrogen A. Nitrogen

1) 5 protons1) 5 protons 2) 7 protons 3) 14 2) 7 protons 3) 14 protonsprotons

B. Sulfur B. Sulfur

1) 32 protons1) 32 protons 2) 16 protons 3) 6 protons 2) 16 protons 3) 6 protons

C. BariumC. Barium

1) 137 protons 2) 81 protons 3) 56 protons1) 137 protons 2) 81 protons 3) 56 protons

1111

Solution AT 1Solution AT 1

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

A. Nitrogen A. Nitrogen

2) 7 protons 2) 7 protons

B. Sulfur B. Sulfur

2) 16 protons2) 16 protons

C. BariumC. Barium

3) 56 protons3) 56 protons

1212

Number of ElectronsNumber of Electrons

An atom is neutral An atom is neutral The net charge is zeroThe net charge is zero Number of protons = Number of electronsNumber of protons = Number of electrons Atomic number = Atomic number = Number of electronsNumber of electrons

1313

Mass NumberMass Number

Counts the number Counts the number

of of

protons protons and and neutronsneutrons

in an atomin an atom

1414

Atomic SymbolsAtomic Symbols

Show the Show the mass number and atomic numbermass number and atomic number

Give the symbol of the elementGive the symbol of the element

mass numbermass number

23 23 NaNa sodium-23sodium-23

atomic numberatomic number 1111

1515

More Atomic SymbolsMore Atomic Symbols

1616 3131 6565

OO P P Zn Zn

88 1515 3030

8 p8 p++ 15 p15 p++ 30 p30 p++

8 n8 n 16 n16 n 35 n35 n8 e8 e-- 1515 ee-- 30 e30 e--

1616

IsotopesIsotopes

Atoms with the same number of protons, Atoms with the same number of protons,

but different numbers of neutrons. but different numbers of neutrons.

Atoms of the same element (same atomic Atoms of the same element (same atomic

number) with different mass numbersnumber) with different mass numbers

Isotopes of chlorineIsotopes of chlorine

3535ClCl 3737ClCl1717 1717

chlorine - 35 chlorine - 37chlorine - 35 chlorine - 37

1717

Learning Check AT 2Learning Check AT 2

Naturally occurring carbon consists of three Naturally occurring carbon consists of three isotopes, isotopes, 1212C, C, 1313C, and C, and 1414C. State the number of C. State the number of protons, neutrons, and electrons in each of protons, neutrons, and electrons in each of these carbon atomsthese carbon atoms. .

1212CC 1313CC 1414CC 66 6 6 6 6

#P _______ _______ _______ #P _______ _______ _______

#N _______ _______ _______#N _______ _______ _______

#E _______ _______#E _______ _______

1818

Solution AT 2Solution AT 2

1212CC 1313CC 1414CC 66 6 6 6 6

#P #P __6_____6___ _ 6____ 6___ ___ ___66___ ___

#N __#N __66___ ____ _ __77___ ______ ___88___ ___

#E #E __6_____6___ _ 6____ 6___ ___ ___66___ ___

1919

Learning Check AT 3Learning Check AT 3An atom of zinc has a mass number of 65.An atom of zinc has a mass number of 65.

A.A. Number of protons in the zinc atomNumber of protons in the zinc atom

1) 301) 30 2) 352) 35 3) 653) 65

B.B. Number of neutrons in the zinc atomNumber of neutrons in the zinc atom

1) 301) 30 2) 352) 35 3) 653) 65

C. What is the mass number of a zinc isotope C. What is the mass number of a zinc isotope

with 37 neutrons?with 37 neutrons?

1) 371) 37 2) 652) 65 3) 673) 67

2020

Solution AT 3Solution AT 3

An atom of zinc has a mass number of 65.An atom of zinc has a mass number of 65.

A.A. Number of protons in the zinc atomNumber of protons in the zinc atom

1) 301) 30

B.B. Number of neutrons in the zinc atomNumber of neutrons in the zinc atom

2) 352) 35

C. What is the mass number of a zinc isotope C. What is the mass number of a zinc isotope

with 37 neutrons?with 37 neutrons?

3) 673) 67

2121

Learning Check AT 4Learning Check AT 4

Write the atomic symbols for atoms with the Write the atomic symbols for atoms with the following:following:

A. 8 pA. 8 p++, 8 n, 8 e, 8 n, 8 e-- ______________________

B.B. 17p17p++, 20n, 17e, 20n, 17e-- ______________________

C. 47pC. 47p++, 60 n, 47 e, 60 n, 47 e-- ______________________

2222

Solution AT 4Solution AT 4

1616OOA. 8 pA. 8 p++, 8 n, 8 e, 8 n, 8 e-- 88

B.B. 17p17p++, 20n, 17e, 20n, 17e-- 3737ClCl 1717

C. 47pC. 47p++, 60 n, 47 e, 60 n, 47 e-- 107107AgAg 4747

2323

Learning Check AT 5Learning Check AT 5

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

1) 141) 14 2) 162) 16 3) 343) 34

B. Its mass number isB. Its mass number is1) 141) 14 2) 162) 16 3) 343) 34

C. The element isC. The element is1) Si1) Si 2) Ca2) Ca 3) Se3) Se

D.D. Another isotope of this element isAnother isotope of this element is

1)1) 3434X X 2)2) 3434X X 3)3) 3636XX 16 16 14 14 14 14

2424

Solution AT 5Solution AT 5

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

1) 141) 14

B. It has a mass number ofB. It has a mass number of3) 343) 34

C. The element isC. The element is1) Si1) Si

D.D. Another isotope of this element would beAnother isotope of this element would be

3) 3) 3636XX 1414

2525

Masses of AtomsMasses of Atoms A scale designed for atoms gives their small A scale designed for atoms gives their small

atomic masses in atomic mass units (amu)atomic masses in atomic mass units (amu)

An atom of An atom of 1212C was assigned an exact mass of C was assigned an exact mass of

12.00 amu12.00 amu

Relative masses of all other atoms was Relative masses of all other atoms was

determined by comparing each to the mass of determined by comparing each to the mass of 1212C C

An atom twice as heavy has a mass of 24.00 An atom twice as heavy has a mass of 24.00

amu. An atom half as heavy is 6.00 amu.amu. An atom half as heavy is 6.00 amu.

2626

Atomic MassAtomic Mass

Listed on the periodic tableListed on the periodic table

Gives the mass of “average” atom of each Gives the mass of “average” atom of each

element compared to element compared to 1212C C

Average atom based on all the isotopes and their Average atom based on all the isotopes and their

abundance %abundance %

Atomic mass is not a whole numberAtomic mass is not a whole number

Na22.99

2727

Learning Check AT6Learning Check AT6

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

A.A. calciumcalcium ____________________

B. aluminumB. aluminum ____________________

C. C. leadlead ____________________

D. bariumD. barium ____________________

E. ironE. iron ____________________

2828

Solution AT6Solution AT6

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

A.A. calciumcalcium _40.1 amu _ _40.1 amu _

B. aluminumB. aluminum _27.0 amu __27.0 amu _

C. C. leadlead __207.2 amu207.2 amu__

D. bariumD. barium _137.3 amu__137.3 amu_

E. ironE. iron _55.8 amu___55.8 amu__

2929

Calculating Atomic MassCalculating Atomic Mass

Percent(%) abundance of isotopesPercent(%) abundance of isotopes

Mass of each isotope of that elementMass of each isotope of that element

Weighted average =Weighted average =

mass isotopemass isotope11(%)(%) + + mass isotopemass isotope22(%)(%) + … + …

100100 100100

3030

Atomic Mass of MagnesiumAtomic Mass of Magnesium

Isotopes Isotopes Mass of Isotope AbundanceMass of Isotope Abundance 2424Mg Mg == 24.0 amu 24.0 amu 78.70%78.70%

2525Mg Mg = = 25.0 amu 25.0 amu 10.13%10.13%

2626Mg Mg = = 26.0 amu26.0 amu 11.17%11.17%

Atomic mass (average mass) Mg = 24.3 amuAtomic mass (average mass) Mg = 24.3 amu

Mg24.3

3131

Learning Check AT7Learning Check AT7

Gallium is a metallic element found in Gallium is a metallic element found in

small lasers used in compact disc players. small lasers used in compact disc players.

In a sample of gallium, there is 60.2% of In a sample of gallium, there is 60.2% of

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

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

atomic mass of galliumatomic mass of gallium??

3232

Solution AT7Solution AT7

Ga-69 Ga-69

68.9 amu x 68.9 amu x 60.2 60.2 = = 41.5 amu for 41.5 amu for 6969GaGa

100100

Ga-71 (%/100)Ga-71 (%/100)

70.9 amu x 70.9 amu x 39.8 39.8 = = 28.2 amu for 28.2 amu for 7171GaGa

100100

Atomic mass Ga Atomic mass Ga = = 69.7 amu69.7 amu

3333

Finding An Isotopic MassFinding An Isotopic Mass

A sample of boron consists of A sample of boron consists of 1010B (mass B (mass 10.0 amu) and 10.0 amu) and 1111B (mass 11.0 amu). If B (mass 11.0 amu). If the average atomic mass of B is 10.8 the average atomic mass of B is 10.8 amu, what is the % abundance of each amu, what is the % abundance of each boron isotope?boron isotope?

3434

Assign X and Y values:Assign X and Y values:X = % X = % 1010B Y = % B Y = % 1111B B

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

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

100 100100 100

Multiply through by 100Multiply through by 10010.0 X + 1100 - 11.0X = 108010.0 X + 1100 - 11.0X = 1080

3535

Collect X terms Collect X terms

10.0 X - 11.0 X = 1080 - 110010.0 X - 11.0 X = 1080 - 1100

- 1.0 X = -20 - 1.0 X = -20

X = X = -20-20 = 20 % = 20 % 1010BB

- 1.0- 1.0

Y = 100 - XY = 100 - X

% % 1111B = 100 - 20% = 80% B = 100 - 20% = 80% 1111BB