Atomic Structure ©2010 - Doug Gilliland The Physical Science Series A Helium atom + +

AtomicStructureAtomic

Structure

©2010 - Doug GillilandThe Physical Science Series

A Helium atom

+ +

Atomic Structure MenuAtomic Structure Menu

Protons, Neutrons & Electrons

Isotopes

Bohr Model

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Over the past centuryscientist have discovered that the atom is composed of 3 subatomic particles:

Protons+

NeutronsElectrons

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The ProtonThe Proton+1) Symbol = P +

2) Relative Mass = 1 Atomic Mass Unit (AMU). Actual mass = 1.674 x 10 -24 g3) Location: Inside the nucleus4) Electrical charge: Positive.5) Importance: The atomic number which is the identity of the element. 6) Discovered by: Ernest Rutherford in 1909

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The ElectronThe Electron1) Symbol = e-

2) Relative Mass = 1 /1836 Atomic Mass Unit. Actual mass = 9.11 x 10 -28 g3) Location: Energy level outside the nucleus4) Electrical charge: Negative.5) Importance: The number of electrons located in the last energy level determinethe chemical activity of the element.6) Discovered by: J.J.Thomson in 1897

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The NeutronThe Neutron1) Symbol = N0

2) Relative Mass = 1 Atomic Mass Unit (AMU). Actual mass = 1.675 x 10 -24 g3) Location: Inside the nucleus4) Electrical charge: Neutral.5) Importance: Is responsible for isotopes (atoms of the same element with different numbers of neutrons).6) Discovered by: James Chadwick in 1932

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Li3

6.941 4 neutrons

+ ++

nucleus

3 protons

3 electronsAtomic Number# of protons =# of electrons

Atomic MassWhen rounded to a whole number it is the total number of protons &

neutrons added together.

An element's Square on the Periodic Table

An element's Square on the Periodic Table

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Element Protons Neutrons Electrons

Silver 47 61 47

Potassium 19 20 19

Neon 10 10 10

Hydrogen 1 0 1

Sulfur 16 16 16


Zinc 30 35 30

Uranium 92 146 92

Gold 79 118 79

Fluorine 9 10 9

Cesium 55 78 55

Fill in the table of p+, n0 and e-.


Silver

Potassium

Neon

Hydrogen

Sulfur

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IsotopesIsotopes•Isotopes are atoms of the same element that have different masses due to having different numbers of neutrons.•The atomic mass (weight) on the periodic table is the average of the abundance of all the isotopes of an element.

++

H-1

99.985%

++

H-2

0.014%

++

H-3

0.001%

Isotope:

Abundance:Menu

++proton

neutronelectron

Isotopes and Atomic Mass

++

H-1

99.985%

++

H-2

0.014%

++

H-3

0.001%

Isotope:

Abundance:

++proton

neutronelectron

1 amu 2 amu 3 amu

Average(numerical) = (1+2+3)/3 = 2 amuAverage(abundance) =

[1(0.99985)+2(0.00014)+3(0.00001)] 3

= 1.00016 amu

Atomic Mass

(approx.)

QuickTime™ and aH.263 decompressor

are needed to see this picture.

Isotopes

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Chemical SymbolsChemical SymbolsA chemical symbol is a short-hand way of writing the name of an element.

Chemical symbols consists of either one or two letters.

The first letter is always uppercase (capitalized). If there is a second letter, it is lowercased and half the size of the first letter.

Correct : Mg, He, Li, Be, Ca, Au, Fe

Incorrect: HE, he, HE, He

A chemical symbol is a short-hand way of writing the name of an element.

Chemical symbols consists of either one or two letters.

The first letter is always uppercase (capitalized). If there is a second letter, it is lowercased and half the size of the first letter.

Correct : Mg, He, Li, Be, Ca, Au, Fe

Incorrect: HE, he, HE, He

H1

1.0079He

2

4.002

Where did the chemical symbols come from?

Where did the chemical symbols come from?

Most symbols came from first one or two letters in the English name of the element.Examples: H = hydrogen, He = helium,Ne = neon, Al = aluminum, S = sulfur

Others come from the first one or two letters in the Latin words for the element. Examples: Pb = lead (plumbum), Sn = tin (stannum), Cu = copper (cuprum) Fe = iron (ferrum), Ag = silver (agrum)

Most symbols came from first one or two letters in the English name of the element.Examples: H = hydrogen, He = helium,Ne = neon, Al = aluminum, S = sulfur

Others come from the first one or two letters in the Latin words for the element. Examples: Pb = lead (plumbum), Sn = tin (stannum), Cu = copper (cuprum) Fe = iron (ferrum), Ag = silver (agrum)

Where did the chemical names come from?

Where did the chemical names come from?

The elements names came from:Planets: Neptunium, Plutonium, Mercury...People: Einsteinium, Curium, Nobelium...Places: Gallium (France), Europium, Polonium...Color: Chlorine (yellow-green in Latin), Indium (Indigo), Iodine ( violet in Greek)Myth: Thorium (Norse war god), Titanium (Titan)...Minerals: Calcium (chalk), Boron (borax)...

The only thing you cannot name an element after is a living human.

The elements names came from:Planets: Neptunium, Plutonium, Mercury...People: Einsteinium, Curium, Nobelium...Places: Gallium (France), Europium, Polonium...Color: Chlorine (yellow-green in Latin), Indium (Indigo), Iodine ( violet in Greek)Myth: Thorium (Norse war god), Titanium (Titan)...Minerals: Calcium (chalk), Boron (borax)...

The only thing you cannot name an element after is a living human.

Mendeleev’s Table

Mendeleev’s Table

18718722

18618699

Mendeleev’s Table (1871)Mendeleev’s Table (1871)While it was the first periodic table, Mendeleev had While it was the first periodic table, Mendeleev had very different elements, such as the very reactive very different elements, such as the very reactive

potassium and potassium and the very stable copper, in the same family. Forty the very stable copper, in the same family. Forty

years later Henry Moseley rearranged the elements years later Henry Moseley rearranged the elements by their atomic number which gave the table better by their atomic number which gave the table better

periodicity.periodicity.Dimitri Dimitri

MendeleeMendeleevv

Long form of the TableLong form of the Table

Short form of the TableShort form of the TableHenry MoseleyHenry Moseley

In 1915 Moseley rearranged In 1915 Moseley rearranged the elements by theirthe elements by their

atomic number. This gaveatomic number. This gaveelements better periodicity.elements better periodicity.

These elements are These elements are placed here to make theplaced here to make the

table less wide.table less wide.

The Chinese Periodic TableThe Chinese Periodic Table

Russian Periodic Table

Russian Periodic Table

Most Abundant Elements:

Most Abundant Elements:

All stars create energy by converting hydrogen to

helium.

The Bohr Model of the The Bohr Model of the AtomAtom

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So what does an atom “look” like?

Bohr Model- electrons travel in fixed circular orbits around the nucleus in discrete energy states- electrons occupy the lowest energy level (ground state) until they absorb energy and move to a farther orbit level (excited state)

Quantum-mechanical model- electrons do not travel in fixed orbits- the energy of an atom occurs in discrete levels- accounts for wave and particle nature of matter and energy- exact location of an electron is impossible to know

11p+12N

0

The Bohr Model places protons and neutrons in the

nucleus and electrons in energy levels around the

nucleus.These energy levels help

explain the organization of the Periodic Table of

Elements.

The Bohr Model of the The Bohr Model of the AtomAtom

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IA

IIA IIIA IVA VA VIA VIIA

VIIIA

Periods and FamiliesPeriods and Families

1

34567

2

67

Periods 1-7 run across the periodic table. The period number is the number of electron energy levels.All elements of a period have the same number of e- energy

levels.

Groups (aka Families) run down the table.Members of a group (with the exception of He) have the same

number of electrons in their outside energy level. These e- are called valence electrons.

Iodine would have 5 e- energy levels and 7

valence e-. Peri

ods

Groups (Families)

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In the early 1900's, scientists discovered that it was the

valence electrons of an atom(the electrons in the last energy

level) that determined how elements

reacted with each other.

The Importance ofValence Electrons

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element e- energy levels

valence e-

Ca 4 2

F 2 7

Al 3 3

K 4 1

Fill in the table with e- energy levels & valence e-.

element e- energy levels

valence e-

C 2 4

P 3 5

Rn 6 8

H 1 1

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Through experimentation Neils Bohr was able to

determine the Maximum number of

electrons in each energy level:

energy level

1st(s)

2nd(p)

3rd(d)

4th(f) 5th 6th 7th

maximum number of electrons 2 8

18

32

18

8 2

This is the largest number of electrons each energy level can

hold.There can be less than this

number but not more.

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Drawing a Bohr Model of a Strontium atom

Draw a circle to represent the nucleus and write in the number of protons and

neutrons.

Sr38

87.62

Step1

38 p

+

50 n0

88 = p+ + n0

-38 = p+

50 n0

Number of Protons

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Draw the correct number of e- energy levels in the atom (Period #). Draw

only a section of the circle to represent the energy level.

38 p50 n

+0Sr

38

87.62

5Period


Step2

Draw only part of the e- energy

level.

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Fill in the last energy level with the correct

number of electrons (group A number).You always do the last e- energy level

first!

38 p50 n

+0

2Sr38

87.62

5Period

IIAGroup


Step3

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Go to the first e- energy level and fill itwith the maximum number of electrons.Do this with the other energy levels until

you get to the 2nd to the last energy level.

38 p50 n

+0

22 188Sr38

87.62


Step4

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38 p50 n

+0

22 188

Add up the number of e- you have and subtract it from the total number of e-

(atomic number). Place thosee- in that 2nd to the last energy level.

38 e-

8 e-8+ + + = e-30


Step5

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Draw a Bohr Model of:Aluminum

Bromine 13 p14 n

+0

2 38

35 p45 n

+0

72 188

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IAIA

IIAIIA IIIAIIIA IVAIVA VAVA VIAVIA VIIAVIIA

VIIIAVIIIA

Periods and FamiliesPeriods and Families

11

3344556677

22

6677

Periods run Periods run horizontally.horizontally.

All elements of a period All elements of a period have the same number have the same number

of of electron energy levels.electron energy levels.All the elements fromAll the elements from

rubidium to xenon rubidium to xenon havehave

5 electron energy 5 electron energy levels.levels.

Families (aka Groups) Families (aka Groups) run vertically.run vertically.

All elements of a familyAll elements of a familyhave the same number have the same number

ofofvalence electronsvalence electrons - -

whichwhichdetermine an determine an

element’s chemical & element’s chemical & physical propertiesphysical properties

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VIIIAVIIIA

Alkali Metals, Group 1-ALithium, Sodium,

Potassium,Rubidium, Cesium &

Francium

Alkali Metals, Group 1-ALithium, Sodium,

Potassium,Rubidium, Cesium &

Francium



Alkali Metals: Chemical Activity Alkali Metals: Chemical Activity

As you go down the Alkali Metal Family As you go down the Alkali Metal Family the radii of the atoms becomes greater the radii of the atoms becomes greater

and their hold on the valence electron becomes and their hold on the valence electron becomes weaker. weaker.

Weak hold on valence electron = Weak hold on valence electron = greater chemical activity.greater chemical activity.



LiLi

NaNa

KK

RbRb

CsCs

FrFr

Alkaline Earth Metals, Group 2-A

Less reactive than the alkali metals

but more reactive than the other metals.

Alkaline Earth Metals, Group 2-A

Less reactive than the alkali metals

but more reactive than the other metals.



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VIIIAVIIIA

Radium glows in the Radium glows in the dark and is radioactive.dark and is radioactive.

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VIIIAVIIIA

Transition MetalsGenerally stable metals such as iron, gold, silver, copper,

zinc, & nickel.

Transition MetalsGenerally stable metals such as iron, gold, silver, copper,

zinc, & nickel.QuickTime™ and a

H.263 decompressorare needed to see this picture.

QuickTime™ and aSorenson Video decompressorare needed to see this picture.

Properties of the Elements:Metals, Nonmetals &

Metalloids

Properties of the Elements:Metals, Nonmetals &

Metalloids

7Metalloids

20Nonmetals

82Metals

Boron Family, 3-ABoron, Aluminum,

Gallium,Indium and Thallium.

Boron Family, 3-ABoron, Aluminum,

Gallium,Indium and Thallium.

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VIIIAVIIIA

Two hundred years agoTwo hundred years agoAluminum was the most expensiveAluminum was the most expensive

metal on earth.metal on earth.Napoleon’s favorite guests were Napoleon’s favorite guests were

servedservedon aluminum plates - his second on aluminum plates - his second

favorite ate off gold plates.favorite ate off gold plates.

Carbon Family, 4-AContain a wide variety of

elements from 1 nonmetal (C), 2 metalloids (Si & Ge) and 2 metals

(Pb & Sn).

Carbon Family, 4-AContain a wide variety of

elements from 1 nonmetal (C), 2 metalloids (Si & Ge) and 2 metals

(Pb & Sn).IAIA


VIIIAVIIIA

Nitrogen Family, 5-ANitrogen, Phosphorus, Arsenic, Antimony &

Bismuth.

Nitrogen Family, 5-ANitrogen, Phosphorus, Arsenic, Antimony &

Bismuth.IAIA


VIIIAVIIIA




Oxygen Family, 6-AOxygen, Sulfur,

Selenium,Tellurium & Polonium.

Oxygen Family, 6-AOxygen, Sulfur,

Selenium,Tellurium & Polonium.

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VIIIAVIIIA

Halogens, Group 7-AThe most reactive nonmetals:Fluorine, Chlorine, Bromine,

Iodine & Astatine.

Halogens, Group 7-AThe most reactive nonmetals:Fluorine, Chlorine, Bromine,

Iodine & Astatine.

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VIIIAVIIIA


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Noble Gases, Group 8-AThe inert (non-reactive) gases:

Helium, Neon, Argon, Krypton, Xenon & Radon.

Noble Gases, Group 8-AThe inert (non-reactive) gases:

Helium, Neon, Argon, Krypton, Xenon & Radon.



General Properties of Metals

General Properties of Metals•Silver in color and have luster.

•Solid @ Room Temperature.

•Have high densities.

•Are malleable & ductile.

•Are good conductors of heat & electricity.

•Atoms have between 1-3 valence electrons.

•Atoms have a loose hold on their valence electrons - they give them up easily.

•Corrode (rust) in the presence of oxygen.

•Silver in color and have luster.

•Solid @ Room Temperature.

•Have high densities.

•Are malleable & ductile.

•Are good conductors of heat & electricity.

•Atoms have between 1-3 valence electrons.

•Atoms have a loose hold on their valence electrons - they give them up easily.

•Corrode (rust) in the presence of oxygen.

Periodic Trends:Periods and Metallic

Properties

Periodic Trends:Periods and Metallic

Properties


MMoorree

MMeettaalllliicc

Less MetallicLess Metallic

Periodic Trends:Atomic Radii

Periodic Trends:Atomic Radii

nucleusnucleusvalence e-valence e-

Atomic Radius

AtomAtomTwo variable determine the atomic radius of a Two variable determine the atomic radius of a atom:atom:

the the number of protonsnumber of protons in the nucleus in the nucleus the the number of electron energy levelsnumber of electron energy levels in the in the

atom.atom.The number protons and radius are inversely proportional.The number protons and radius are inversely proportional.As protons increase, the radius decreases.As protons increase, the radius decreases.

The number of energy levels and radius are proportional.The number of energy levels and radius are proportional.As energy levels increase, the radius also increases.As energy levels increase, the radius also increases.

Reactivity of Alkali MetalsReactivity of Alkali MetalsLiLi

NaNa

KK

152152186186227227

Radius inRadius inAngstroms (Å)Angstroms (Å)

Metals lose their Metals lose their valence electrons in a valence electrons in a

chemical reaction.chemical reaction.The easier it is to lose The easier it is to lose the electron the more the electron the more chemically active the chemically active the

element.element.The further the valence The further the valence

electron is from the electron is from the nucleus, the weaker the nucleus, the weaker the hold on the electron and hold on the electron and the easier it is lost to a the easier it is lost to a

nonmetal.nonmetal.

mmoorree

aaccttiivvee

mmoorree

aaccttiivvee

++++

Atomic Radii & ProtonsAtomic Radii & Protons

++

As you go across a period, the As you go across a period, the atoms gain protonsatoms gain protons while while

the number of the number of electron energy levels remain the electron energy levels remain the samesame..

electronelectron Force of Force of AttractionAttraction++protonproton

kkeeyy

Positive protons and negative electrons attract each Positive protons and negative electrons attract each other.other.

ThisThis increase in the number of protons increase in the number of protons causes a causes a greater attraction between the nucleus and the greater attraction between the nucleus and the

electrons in the atom.electrons in the atom.As protons are added, electrons are pulled closer the As protons are added, electrons are pulled closer the

nucleusnucleusgiving the atom a smaller radius as you go across a giving the atom a smaller radius as you go across a

period.period.

++++++

Atomic RadiiAtomic RadiiThe number protons and atomic radii are inversely The number protons and atomic radii are inversely proportional.proportional.

As protons increase across a period, the radius decreases.As protons increase across a period, the radius decreases.The number of energy levels and atomic radii are The number of energy levels and atomic radii are proportional.proportional.

As energy levels increase down a family, the radius also As energy levels increase down a family, the radius also increases.increases.

AtomicAtomicRadiiRadii

increasesincreasesdue todue to

ananincreaseincrease

in thein thenumber number

of e-of e-energyenergylevels.levels.

Atomic Radii of the ElementsAtomic Radii of the ElementsIAIA


VIIIAVIIIAHH

CsCs

LiLi

NaNa

KK

RbRb

MgMg AlAl SiSi PP SS ClCl ArAr


Atomic Radii decreases due to the increase in the number of Atomic Radii decreases due to the increase in the number of protons.protons.

Ionization Energy increase due to increasing # of protons.Ionization Energy increase due to increasing # of protons.

IonizationIonizationEnergyEnergy

decreasesdecreasesas the as the valencevalence

electronselectronsareare

located located fartherfarther

from thefrom thenucleus.nucleus.

Ionization Energy of the ElementsIonization Energy of the Elements

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VIIIAVIIIAHH

CsCs

LiLi

NaNa

KK

RbRb

MgMg AlAl SiSi PP SS ClCl ArAr

Ionization energy is the energy required to Ionization energy is the energy required to remove a valence electron from an atom.remove a valence electron from an atom.

The Periodic The Periodic TableTable

Atomic Radii decreasesAtomic Radii decreasesAtomic Radii decreasesAtomic Radii decreases

Valence electrons Valence electrons increaseincrease

Valence electrons Valence electrons increaseincrease

Metallic properties Metallic properties decreasedecrease

Metallic properties Metallic properties decreasedecrease

Summing Up Periodic Summing Up Periodic TrendsTrends

Ionization Energy Ionization Energy increasesincreases

Ionization Energy Ionization Energy increasesincreases

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eenneerrggyy ddeeccrreeaasseess

IIoonniizzaattiioonn

eenneerrggyy ddeeccrreeaasseess

MMeettaalllliicc

pprrooppeerrttiieess

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MMeettaalllliicc

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This table is called a This table is called a PeriodicPeriodic Table Table because periodic trends occur as you because periodic trends occur as you

go down go down families and across periods.families and across periods.

We will use these periodic trends to We will use these periodic trends to understand how elements combine to understand how elements combine to form compounds in the next chapter.form compounds in the next chapter.

Graphing Periodic Trends

Please take out your Please take out your lablab and the and the Bohr Model of the Bohr Model of the Atom Atom program sheet so you program sheet so you can look at the models you can look at the models you

drew on the back.drew on the back.

The atomic radii decreasesThe atomic radii decreasesbecause more protons arebecause more protons are

added to the nucleus.added to the nucleus.This causes the electronsThis causes the electrons

to be pulled closerto be pulled closerto the nucleus.to the nucleus.

The energy required The energy required to remove an electronto remove an electron

becomes greater becausebecomes greater becausethere are more protonsthere are more protons

in the atom in the atom (greater attraction).(greater attraction).

As you go across a As you go across a period, the valence period, the valence electrons in the A-electrons in the A-groups increase by groups increase by

one.one.

As you go down the As you go down the Alkali Metals, the valence electrons Alkali Metals, the valence electrons

get further from the nucleus and get further from the nucleus and are easier to remove from the are easier to remove from the

atom.atom.The lower the ionization energyThe lower the ionization energythe higher the chemical activity.the higher the chemical activity.

As you go down the As you go down the Alkali Metals, the valence electrons Alkali Metals, the valence electrons

get further from the nucleus and get further from the nucleus and are easier to remove from the are easier to remove from the

atom.atom.The lower the ionization energyThe lower the ionization energythe higher the chemical activity.the higher the chemical activity.

As you go down the Alakali As you go down the Alakali Metals family, the number of Metals family, the number of e- energy levels increases. e- energy levels increases.

This causes their atomic radii This causes their atomic radii to increase.to increase.

As you go down the As you go down the Halogen family, Halogen family,

the valence electrons getthe valence electrons getfurther from the nucleus and further from the nucleus and

are easier to remove are easier to remove from the atom.from the atom.

As you go down the As you go down the Halogen family, Halogen family,

the valence electrons getthe valence electrons getfurther from the nucleus and further from the nucleus and

are easier to remove are easier to remove from the atom.from the atom.

As you go down the Halogen As you go down the Halogen family, the number of e- family, the number of e-

energy levels increases. This energy levels increases. This causes thecauses the

atomic radii to increase.atomic radii to increase.

Atomic Structure ©2010 - Doug Gilliland The Physical Science Series A Helium atom + +

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Transcript of Atomic Structure ©2010 - Doug Gilliland The Physical Science Series A Helium atom + +