PERIODICITYPERIODICITY

Table of ContentsTable of Contents

Electron Configurations pg. 3History of the Periodic Table pg. 11Periodic Properties pg. 16Atomic Radius pg. 17Ionic Radius pg. 24Ionic Charge pg. 27Ionization Energy pg. 32Electron Affinity pg. 38Octet Rule pg. 40Electronegativity pg. 43Other Periodic Trends pg. 45Questions pg. 49

• Don’t have to write out the entire Don’t have to write out the entire electron configuration. electron configuration.

• There is a short-cut:There is a short-cut:– Keeps focus on Keeps focus on valence electronsvalence electrons– An atom’s inner electrons are An atom’s inner electrons are

represented by the symbol for represented by the symbol for the nearest noble gas with a the nearest noble gas with a lower atomic number.lower atomic number.

• Don’t have to write out the entire Don’t have to write out the entire electron configuration. electron configuration.

• There is a short-cut:There is a short-cut:– Keeps focus on Keeps focus on valence electronsvalence electrons– An atom’s inner electrons are An atom’s inner electrons are

represented by the symbol for represented by the symbol for the nearest noble gas with a the nearest noble gas with a lower atomic number.lower atomic number.

K: [Ar]4s1

Electron Configurations

For the element Phosphorus -- 15 electrons

1s22s22p63s23p3

[Ne]P:Must be aNoble gas

(One just before Element)

Electron Configurations

3s23p3

Let’s do a couple more:Let’s do a couple more:

Ba:Ba:[Xe][Xe]6s6s22

Hg:Hg:[Xe][Xe]6s6s22

V:V:[Ar][Ar]4s4s22

Electron ConfigurationsElectron Configurations

4f4f14145d5d1010

3d3d33

Exceptions to the order of fillingExceptions to the order of filling

• The chemistry of an atom occurs at The chemistry of an atom occurs at the set of electrons called the set of electrons called valence valence electronselectrons

• The valence electrons are electrons The valence electrons are electrons in an atom’s in an atom’s highest energy levelhighest energy level. . – For the Group – A elements, it is the For the Group – A elements, it is the

outermost s & p eoutermost s & p e-- of the atom. of the atom.– Specifically the 2 s electrons + 6 p Specifically the 2 s electrons + 6 p

electrons electrons (octet electrons)(octet electrons)• The arrangement of the valence eThe arrangement of the valence e--

lead to the element’s properties.lead to the element’s properties.

• The chemistry of an atom occurs at The chemistry of an atom occurs at the set of electrons called the set of electrons called valence valence electronselectrons

• The valence electrons are electrons The valence electrons are electrons in an atom’s in an atom’s highest energy levelhighest energy level. . – For the Group – A elements, it is the For the Group – A elements, it is the

outermost s & p eoutermost s & p e-- of the atom. of the atom.– Specifically the 2 s electrons + 6 p Specifically the 2 s electrons + 6 p

electrons electrons (octet electrons)(octet electrons)• The arrangement of the valence eThe arrangement of the valence e--

lead to the element’s properties.lead to the element’s properties.

Electron Configurations

• 70 elements had been discovered 70 elements had been discovered by the mid-1800’s, but until Dmitri by the mid-1800’s, but until Dmitri MendeleevMendeleev, no one had a come with , no one had a come with a way to organize the elements.a way to organize the elements.– Mendeleev came up with the first Mendeleev came up with the first

working system of filing the working system of filing the elements.elements.

• He listed the elements in columns in He listed the elements in columns in order of order of increasing atomic massincreasing atomic mass, , and then put columns together that and then put columns together that were similarwere similar

• 70 elements had been discovered 70 elements had been discovered by the mid-1800’s, but until Dmitri by the mid-1800’s, but until Dmitri MendeleevMendeleev, no one had a come with , no one had a come with a way to organize the elements.a way to organize the elements.– Mendeleev came up with the first Mendeleev came up with the first

working system of filing the working system of filing the elements.elements.

• He listed the elements in columns in He listed the elements in columns in order of order of increasing atomic massincreasing atomic mass, , and then put columns together that and then put columns together that were similarwere similar

History of the Periodic TableHistory of the Periodic Table

•Mendeleev left gaps in the table Mendeleev left gaps in the table since there were no current since there were no current elements that seemed to fit elements that seemed to fit those spotsthose spots– Those elements were eventually Those elements were eventually

discovered and they fit perfectly discovered and they fit perfectly into an open spot.into an open spot.

•The 1The 1stst scientist that set the scientist that set the table in order of table in order of atomic numberatomic number was Henry was Henry MoseleyMoseley

•Mendeleev left gaps in the table Mendeleev left gaps in the table since there were no current since there were no current elements that seemed to fit elements that seemed to fit those spotsthose spots– Those elements were eventually Those elements were eventually

discovered and they fit perfectly discovered and they fit perfectly into an open spot.into an open spot.

•The 1The 1stst scientist that set the scientist that set the table in order of table in order of atomic numberatomic number was Henry was Henry MoseleyMoseley

History of the Periodic TableHistory of the Periodic Table

• The modern PT is arranged by The modern PT is arranged by increasing atomic numberincreasing atomic number– Increases from left to right, and Increases from left to right, and

top to bottomtop to bottom • This establishes the This establishes the periodic lawperiodic law

– When the elements are arranged When the elements are arranged in order of increasing atomic #, in order of increasing atomic #, there is a there is a periodic repetitionperiodic repetition of of their phys & chem propertiestheir phys & chem properties

• The modern PT is arranged by The modern PT is arranged by increasing atomic numberincreasing atomic number– Increases from left to right, and Increases from left to right, and

top to bottomtop to bottom • This establishes the This establishes the periodic lawperiodic law

– When the elements are arranged When the elements are arranged in order of increasing atomic #, in order of increasing atomic #, there is a there is a periodic repetitionperiodic repetition of of their phys & chem propertiestheir phys & chem properties

History of the Periodic TableHistory of the Periodic Table

• An element’s properties can go An element’s properties can go hand in hand with electron hand in hand with electron arrangementarrangement

• We can use an element’s location on We can use an element’s location on the PT to predict many properties.the PT to predict many properties.– Atomic radius Atomic radius – Electron affinityElectron affinity– ElectronegativityElectronegativity– Ionization energyIonization energy– Ionic SizeIonic Size

• An element’s properties can go An element’s properties can go hand in hand with electron hand in hand with electron arrangementarrangement

• We can use an element’s location on We can use an element’s location on the PT to predict many properties.the PT to predict many properties.– Atomic radius Atomic radius – Electron affinityElectron affinity– ElectronegativityElectronegativity– Ionization energyIonization energy– Ionic SizeIonic Size

Periodic Properties

•The radius of an atom is defined The radius of an atom is defined by the edge of its last energy by the edge of its last energy level.level.– However, this boundary is fuzzyHowever, this boundary is fuzzy

•An atom’s radius is the An atom’s radius is the measured distancemeasured distance between the between the nuclei of 2 identical atoms nuclei of 2 identical atoms chemically bonded together - chemically bonded together - divided by 2divided by 2..

•The radius of an atom is defined The radius of an atom is defined by the edge of its last energy by the edge of its last energy level.level.– However, this boundary is fuzzyHowever, this boundary is fuzzy

•An atom’s radius is the An atom’s radius is the measured distancemeasured distance between the between the nuclei of 2 identical atoms nuclei of 2 identical atoms chemically bonded together - chemically bonded together - divided by 2divided by 2..

Periodic Properties

• As we examine atomic radius from As we examine atomic radius from left to right across the PT we see a left to right across the PT we see a grad-ual grad-ual decrease in atomic sizedecrease in atomic size..– As eAs e-- are added to the are added to the s and p s and p

sublevelssublevels in the same energy level, in the same energy level, they are gradually pulled closer to they are gradually pulled closer to the the highly positive nucleushighly positive nucleus

• The more eThe more e--’s in the atom the less ’s in the atom the less dramatic this trend looksdramatic this trend looks

• As we examine atomic radius from As we examine atomic radius from left to right across the PT we see a left to right across the PT we see a grad-ual grad-ual decrease in atomic sizedecrease in atomic size..– As eAs e-- are added to the are added to the s and p s and p

sublevelssublevels in the same energy level, in the same energy level, they are gradually pulled closer to they are gradually pulled closer to the the highly positive nucleushighly positive nucleus

• The more eThe more e--’s in the atom the less ’s in the atom the less dramatic this trend looksdramatic this trend looks

Periodic Properties

• The change in atomic radii across The change in atomic radii across the PT is due to ethe PT is due to e-- shieldingshielding or to or to the the effective nuclear chargeeffective nuclear charge– As we move across As we move across

the PT we are adding the PT we are adding e e-- into the same gen- into the same gen- eral vol. in which case eral vol. in which case they will they will shield or shield or interact interact with each with each other ( other (repulsionrepulsion))

• The change in atomic radii across The change in atomic radii across the PT is due to ethe PT is due to e-- shieldingshielding or to or to the the effective nuclear chargeeffective nuclear charge– As we move across As we move across

the PT we are adding the PT we are adding e e-- into the same gen- into the same gen- eral vol. in which case eral vol. in which case they will they will shield or shield or interact interact with each with each other ( other (repulsionrepulsion))

Periodic Properties

– We are also adding protons into We are also adding protons into the nucleus which increases the the nucleus which increases the pp++-e-e-- interaction (attraction) interaction (attraction)

• So the nucleus gains strength So the nucleus gains strength while the ewhile the e-- aren’t gaining much aren’t gaining much distance, so the atom is drawn in distance, so the atom is drawn in closer and closer to the nucleus.closer and closer to the nucleus.– Decreasing the overall radius of Decreasing the overall radius of

the atomthe atom

– We are also adding protons into We are also adding protons into the nucleus which increases the the nucleus which increases the pp++-e-e-- interaction (attraction) interaction (attraction)

• So the nucleus gains strength So the nucleus gains strength while the ewhile the e-- aren’t gaining much aren’t gaining much distance, so the atom is drawn in distance, so the atom is drawn in closer and closer to the nucleus.closer and closer to the nucleus.– Decreasing the overall radius of Decreasing the overall radius of

the atomthe atom

Periodic Properties

• How does the size of an atom How does the size of an atom change when electrons are change when electrons are added or removed?added or removed?

• How does the size of an atom How does the size of an atom change when electrons are change when electrons are added or removed?added or removed?

As an Atom loses As an Atom loses 1 or more 1 or more electrons electrons (becomes (becomes

positive)positive), it loses , it loses a layer therefore, a layer therefore,

its radius its radius decreases.decreases.

Periodic Properties

• How does the size of an atom How does the size of an atom change when electrons are change when electrons are added or removed?added or removed?

As an Atom gains As an Atom gains 1 or more 1 or more electrons electrons

((negative)negative), it fills , it fills its valence layer, its valence layer,

therefore, its therefore, its radius increases.radius increases.

Periodic Properties

• Elements in a group tend to form Elements in a group tend to form ions of the same charge.ions of the same charge.– Modeled by electron Modeled by electron

configurations.configurations.

• Elements in a group tend to form Elements in a group tend to form ions of the same charge.ions of the same charge.– Modeled by electron Modeled by electron

configurations.configurations.

[Ar][Ar]4sLoses 1

electron Loses 1

electron

Wants a full set of e- Wants a full set of e-

[Ar][Ar]4s4s

K:K:

Periodic Properties

[He][He][He][He]

Gains 2 electrons

Gains 2 electrons

Wants a complete set Wants a complete set

O:O:2s22s2 2p42p4

Periodic Properties

Periodic Trend of Ionic ChargesPeriodic Trend of Ionic Charges

The Transition Elements are almost unpredictable, and sometimes have more than one possible charge -- due to d orbitals --

The Transition Elements are almost unpredictable, and sometimes have more than one possible charge -- due to d orbitals --

Tend to Tend to lose lose electrons electrons to become to become positivepositive

Tend to Tend to lose lose electrons electrons to become to become positivepositive

Tend to gain Tend to gain electrons to electrons to

become become negativenegative

• Another periodic trend on the Another periodic trend on the table is table is ionization energyionization energy (a.k.a. (a.k.a. potential)potential)– Which is the energy needed to Which is the energy needed to

remove one of an atoms eremove one of an atoms e--s.s.– Or a measure of how strongly an Or a measure of how strongly an

atom holds onto its atom holds onto its outermost eoutermost e--ss..• If the eIf the e--s are held strongly the s are held strongly the

atom will have a atom will have a highhigh ionization ionization energyenergy

• Another periodic trend on the Another periodic trend on the table is table is ionization energyionization energy (a.k.a. (a.k.a. potential)potential)– Which is the energy needed to Which is the energy needed to

remove one of an atoms eremove one of an atoms e--s.s.– Or a measure of how strongly an Or a measure of how strongly an

atom holds onto its atom holds onto its outermost eoutermost e--ss..• If the eIf the e--s are held strongly the s are held strongly the

atom will have a atom will have a highhigh ionization ionization energyenergy

Periodic Properties

•The ionization energy is The ionization energy is generally measured for generally measured for one one electron at a timeelectron at a time

•You can also measure the You can also measure the amount of energy needed to amount of energy needed to reach in and pluck out additional reach in and pluck out additional electrons from atoms.electrons from atoms.

– There is generally a There is generally a large jump large jump in energy in energy necessary to necessary to remove additional electrons remove additional electrons from the atom.from the atom.

Periodic Properties

the amount of energy required to the amount of energy required to remove a remove a 2p e2p e–– (an e (an e- - in a full in a full

sublevel) from a Na ion is almost 10 sublevel) from a Na ion is almost 10 times greater than that required to times greater than that required to

remove the sole remove the sole 3s e3s e--

• There is simply not enough There is simply not enough energy available or released to energy available or released to produce an Naproduce an Na2+2+ ion to make the ion to make the compnd compnd NaClNaCl22– Similarly MgSimilarly Mg3+3+ and Al and Al4+4+ require require

too much energy to occur too much energy to occur naturally.naturally.

• Chemical formulas should Chemical formulas should always describe compounds that always describe compounds that can exist naturally the most can exist naturally the most efficient way possibleefficient way possible

Periodic Properties

• Another periodic trend dealing Another periodic trend dealing with an e- is with an e- is electron affinityelectron affinity– Which is a measure of the ability of Which is a measure of the ability of

an atom an atom to attract or gainto attract or gain an an electron.electron.

• Atoms that tend to accept an eAtoms that tend to accept an e-- are those that tend to give a neg. are those that tend to give a neg. charge.charge.– The closer to a full outer shell an The closer to a full outer shell an

atom has, the atom has, the higher the affinityhigher the affinity (more neg. the measurement)(more neg. the measurement)

• Another periodic trend dealing Another periodic trend dealing with an e- is with an e- is electron affinityelectron affinity– Which is a measure of the ability of Which is a measure of the ability of

an atom an atom to attract or gainto attract or gain an an electron.electron.

• Atoms that tend to accept an eAtoms that tend to accept an e-- are those that tend to give a neg. are those that tend to give a neg. charge.charge.– The closer to a full outer shell an The closer to a full outer shell an

atom has, the atom has, the higher the affinityhigher the affinity (more neg. the measurement)(more neg. the measurement)

Periodic Properties

• An atoms ability to lose an eAn atoms ability to lose an e-- or or gain an egain an e-- can be used to can be used to understand the understand the Octet RuleOctet Rule

• Octet Rule: atoms tend to gain, Octet Rule: atoms tend to gain, lose, or share electrons in order lose, or share electrons in order to acquire a to acquire a full set of valence full set of valence electronselectrons..– 2 e2 e-- in the outermost s sublevel in the outermost s sublevel

+ 6 e+ 6 e–– in the outermost p in the outermost p sublevel= a full valence shellsublevel= a full valence shell

• An atoms ability to lose an eAn atoms ability to lose an e-- or or gain an egain an e-- can be used to can be used to understand the understand the Octet RuleOctet Rule

• Octet Rule: atoms tend to gain, Octet Rule: atoms tend to gain, lose, or share electrons in order lose, or share electrons in order to acquire a to acquire a full set of valence full set of valence electronselectrons..– 2 e2 e-- in the outermost s sublevel in the outermost s sublevel

+ 6 e+ 6 e–– in the outermost p in the outermost p sublevel= a full valence shellsublevel= a full valence shell

Periodic Properties

• ElectronegativityElectronegativity is a key trend. is a key trend.– It reflects the ability of an atom It reflects the ability of an atom

to attract electrons in a chemical to attract electrons in a chemical bond.bond.

–FF is the most electronegative is the most electronegative element and it decreases element and it decreases moving away from F.moving away from F.

• Electronegativity correlates to Electronegativity correlates to an atom’s ionization energy and an atom’s ionization energy and electron affinityelectron affinity

• ElectronegativityElectronegativity is a key trend. is a key trend.– It reflects the ability of an atom It reflects the ability of an atom

to attract electrons in a chemical to attract electrons in a chemical bond.bond.

–FF is the most electronegative is the most electronegative element and it decreases element and it decreases moving away from F.moving away from F.

• Electronegativity correlates to Electronegativity correlates to an atom’s ionization energy and an atom’s ionization energy and electron affinityelectron affinity

Periodic Properties

INCREASESINCREASES

INC

REA

SES

INC

REA

SES

BOILING POINT & MELTING POINT VS. ATOMIC NUMBER

BOILING POINT & MELTING POINT VS. ATOMIC NUMBER

QuestionsQuestions

• 1.) Write out the noble gas electron configuration of Tungsten, Tin, Selenium, Uranium, and Silver.

• 2.) What are the valence electrons of the elements from the previous question?

• 3.) Describe how the modern periodic table is arranged.

• 4.) Arrange Lithium, Potassium, and Cesium in order from smallest to largest atomic radius and briefly explain your reasoning for the ordering.

• 5.) Arrange Sulfur, Sodium, and Aluminum in order from smallest to largest atomic radius and briefly explain your reasoning for the ordering.

• 6.) Which has a larger radius, neutral bromine or bromide ion and why?

• 7.) Which has a larger radius, neutral calcium or calcium ion and why?

• 1.) Write out the noble gas electron configuration of Tungsten, Tin, Selenium, Uranium, and Silver.

• 2.) What are the valence electrons of the elements from the previous question?

• 3.) Describe how the modern periodic table is arranged.

• 4.) Arrange Lithium, Potassium, and Cesium in order from smallest to largest atomic radius and briefly explain your reasoning for the ordering.

• 5.) Arrange Sulfur, Sodium, and Aluminum in order from smallest to largest atomic radius and briefly explain your reasoning for the ordering.

• 6.) Which has a larger radius, neutral bromine or bromide ion and why?

• 7.) Which has a larger radius, neutral calcium or calcium ion and why?

QuestionsQuestions

• 8.) Name three elements that typically have a charge of -1, +2, and can take more than one charge.

• 9.) Arrange Chlorine, Sodium, Argon, and Bromine from smallest to largest Ionization energy.

• 10.) Why does KBr2 not exist in nature?

• 11.) Explain why Ionization Energy, Electron Affinity, and Electronegativity all follow the same periodic trend.

• 12.) Arrange Selenium, Platinum, Chlorine, and Nickel from least dense to most dense.

• 13.) Hypothesize why the periodic trends for Atomic Radius and Electron Affinity are opposite to each other.

• 8.) Name three elements that typically have a charge of -1, +2, and can take more than one charge.

• 9.) Arrange Chlorine, Sodium, Argon, and Bromine from smallest to largest Ionization energy.

• 10.) Why does KBr2 not exist in nature?

• 11.) Explain why Ionization Energy, Electron Affinity, and Electronegativity all follow the same periodic trend.

• 12.) Arrange Selenium, Platinum, Chlorine, and Nickel from least dense to most dense.

• 13.) Hypothesize why the periodic trends for Atomic Radius and Electron Affinity are opposite to each other.