Periodic Table – Periodic Table – Organizing the Organizing the

ElementsElementsChapter 5.4Chapter 5.4

& Chapter 14& Chapter 14

Dmitri MendeleevDmitri Mendeleev

About 70 elements had About 70 elements had been found by the mid been found by the mid 1800’s1800’s

Mendeleev was the first to Mendeleev was the first to organize them in a organize them in a systematic waysystematic way

He listed the elements in He listed the elements in order of increasing order of increasing atomic massatomic mass

Arranged the elements in Arranged the elements in columns so those with columns so those with similar properties were similar properties were side by sideside by side

He left blank spaces He left blank spaces where nothing fitwhere nothing fit

He predicted the physical He predicted the physical properties of the missing properties of the missing elementselements

He was mostly correctHe was mostly correct

Henry MoseleyHenry Moseley

Moseley determined the Moseley determined the atomic # of the elements atomic # of the elements and arranged the table and arranged the table by atomic number by atomic number instead of atomic massinstead of atomic mass

The modern periodic table The modern periodic table is arranged by atomic is arranged by atomic number number

The periodic table has The periodic table has atomic # increasing from atomic # increasing from left to right & top to bottomleft to right & top to bottom

Periodic LawPeriodic LawThe horizontal rows on The horizontal rows on the periodic table are the periodic table are called called periodsperiods

Properties change as Properties change as you move across a you move across a periodperiod

The properties repeat The properties repeat when you move from one when you move from one period to the nextperiod to the nextPeriodic LawPeriodic Law: there is a : there is a periodic repetition of the periodic repetition of the chemical & physical chemical & physical properties of the elementsproperties of the elements

GroupsGroups

Each vertical column is Each vertical column is called a called a groupgroup or or familyfamily

Elements in the same Elements in the same group have similar group have similar propertiesproperties

Groups have a number and Groups have a number and a letter (pg 124)a letter (pg 124)The group with Li, Na, K etc The group with Li, Na, K etc is called Group 1Ais called Group 1AGroup 1A elements are also Group 1A elements are also called the called the alkali metalsalkali metals

All group A elements are All group A elements are called the called the representative representative elementselements

They exhibit a wide range They exhibit a wide range of physical & chemical of physical & chemical propertiesproperties

Elements on the left side Elements on the left side of the periodic table of the periodic table (except for hydrogen) are (except for hydrogen) are metalsmetals

Group 2A are the Group 2A are the Alkaline Earth MetalsAlkaline Earth Metals

Group B elements are the Group B elements are the transitiontransition & & inner-transition inner-transition metalsmetals

Gold & silver are transition Gold & silver are transition metalsmetals

Uranium is an inner-Uranium is an inner-transition metaltransition metal

The upper right hand The upper right hand corner of the table has corner of the table has the the non-metalsnon-metals

Some are gases, some Some are gases, some are solids & some are are solids & some are liquids at room liquids at room temperaturetemperature

Bromine is a liquid, Bromine is a liquid, Oxygen is a gas and sulfur Oxygen is a gas and sulfur is a solidis a solidGroup 7A are called the Group 7A are called the Halogens (F, Cl, Br, I) Halogens (F, Cl, Br, I) Group 0 (8A) are the noble Group 0 (8A) are the noble gases (He, Ne, etc)gases (He, Ne, etc)

Metals have a shiny Metals have a shiny appearance (luster) & are appearance (luster) & are good conductors of heat & good conductors of heat & electricity, most are solidselectricity, most are solids

Nonmetals do not have Nonmetals do not have luster & are poor luster & are poor conductorsconductors

Elements bordering the Elements bordering the step-line are called step-line are called metalloidsmetalloids or or semi-metalssemi-metalsSi & Ge are metalloidsSi & Ge are metalloidsThey have properties in-They have properties in-between metals & between metals & nonmetalsnonmetals

The elements can also be The elements can also be classified by their electron classified by their electron configurationconfiguration

Electrons play the most Electrons play the most important part in determining important part in determining the properties of elementsthe properties of elements

Write the electron Write the electron configurations for the Alkali configurations for the Alkali MetalsMetals

What similarities do you see? What similarities do you see?

The Halogens? The Halogens?

The Noble Gases? The Noble Gases?

The noble gases have their The noble gases have their outermost s & p sublevels outermost s & p sublevels filled completelyfilled completely

The Representative The Representative Elements have their Elements have their outermost s & p sublevels outermost s & p sublevels partially filledpartially filled

The Transition Metals – their The Transition Metals – their outermost s & nearby d outermost s & nearby d sublevels contain electronssublevels contain electrons

The Inner Transition Metals – The Inner Transition Metals – their outermost s & nearby f their outermost s & nearby f sublevels contain electronssublevels contain electrons

The Table can be broken up The Table can be broken up into blocks - tell you the into blocks - tell you the outermost sublevels that are outermost sublevels that are filledfilled

s block, p block, d block & f s block, p block, d block & f blockblock

Where are they? Where are they?

Each period on the Table Each period on the Table corresponds to a principle corresponds to a principle energy level being filledenergy level being filled

# electrons can be determined # electrons can be determined by counting left to rightby counting left to right

d block is one less than the d block is one less than the period, f block 2 lessperiod, f block 2 less

The electron configuration The electron configuration can be determined for most can be determined for most of the elements this wayof the elements this way

““S”S” block blockGroups 1 & 2Groups 1 & 2

Electron Configuration ends in an Electron Configuration ends in an SS Sub-level. Sub-level.

Highest energy level is equal to Highest energy level is equal to the period number of the element.the period number of the element.–i.e. Calcium’s (in the 4th period) i.e. Calcium’s (in the 4th period)

electron configuration ends in 4s.electron configuration ends in 4s.

““P”P” block blockGroups 13 thru 18Groups 13 thru 18

Electron Configuration ends in a Electron Configuration ends in a PP Sub-level.Sub-level.

Highest energy level is equal to Highest energy level is equal to the period number of the element.the period number of the element.–i.e. Silicon’s (in the 3rd period) i.e. Silicon’s (in the 3rd period)

electron configuration ends in 3p.electron configuration ends in 3p.

““D”D” block blockGroups 3 thru 12Groups 3 thru 12

Electron Configuration ends in a Electron Configuration ends in a DD Sub-level.Sub-level.

Highest energy level one less than Highest energy level one less than the period number of the element.the period number of the element.–i.e. Silver’s (in the 5th period) i.e. Silver’s (in the 5th period)

electron configuration ends in 4d.electron configuration ends in 4d.

““F”F” block block““Inner Transition Metals”Inner Transition Metals”

Electron Configuration ends in an Electron Configuration ends in an FF Sub-level. Sub-level.

Highest energy level two less than Highest energy level two less than the period number of the element.the period number of the element.–i.e. Uranium’s (in the 7th period) i.e. Uranium’s (in the 7th period)

electron configuration ends in 5f.electron configuration ends in 5f.

Regardless of the “Block,” the number Regardless of the “Block,” the number of electrons in the highest sub-level is of electrons in the highest sub-level is equal to the element’s column number equal to the element’s column number within its block.within its block.

–Ex: Nitrogen is in the 3rd column of Ex: Nitrogen is in the 3rd column of the p block and its configuration the p block and its configuration ends in pends in p33..

–Ex: Iron is in the 6th column of the d Ex: Iron is in the 6th column of the d block and it ends in dblock and it ends in d66..

Examples:Examples:

Determine the last term in the Determine the last term in the electron configurations of the electron configurations of the following elements:following elements:–Chlorine:Chlorine:

3p3p55

–Potassium:Potassium:4s4s11

–Mercury:Mercury:5d5d1010

Stable electron Stable electron configurationsconfigurations

1.1. Ending in a full p sublevel or Ending in a full p sublevel or 1s1s

– Noble gases are the most stableNoble gases are the most stable

2.2. Ending in a full sub-level other Ending in a full sub-level other than a p or the 1s.than a p or the 1s.

– Magnesium (3sMagnesium (3s22) is more stable ) is more stable than Sodium (3sthan Sodium (3s11).).

3.3.Ending in a half-filled multi-Ending in a half-filled multi-orbital (p, d or f) sub-level.orbital (p, d or f) sub-level.

– Nitrogen (2pNitrogen (2p33) is more stable ) is more stable than Carbon (2pthan Carbon (2p22) or Oxygen ) or Oxygen (2p(2p44).).

– Stability due to un-paired Stability due to un-paired electrons in orbitals having same electrons in orbitals having same “Spin.”“Spin.”

Periodic TrendsPeriodic Trends

An element’s placement in the An element’s placement in the periodic table determines periodic table determines characteristics like the size of the characteristics like the size of the atom, its ability to attract electrons atom, its ability to attract electrons and the stability of its electron and the stability of its electron configuration.configuration.

Atomic RadiusAtomic RadiusSize of atoms of each element:Size of atoms of each element:

–How will the size of atoms change How will the size of atoms change as we proceed down a group?as we proceed down a group?

i.e. Compare the sizes of Li and Na.i.e. Compare the sizes of Li and Na.

From Li to Na, we add an entire From Li to Na, we add an entire energy level, therefore the size energy level, therefore the size increases.increases.

How will the size of atoms change How will the size of atoms change as we proceed across a period?as we proceed across a period?–Compare C, N and O. Which is Compare C, N and O. Which is

largest?largest?Oxygen has the most electrons.Oxygen has the most electrons.

However, it also has the most protons.However, it also has the most protons.

The outermost electrons of Oxygen The outermost electrons of Oxygen are in the same sub-level as C and N.are in the same sub-level as C and N.

Oxygen’s greater nuclear charge Oxygen’s greater nuclear charge attracts the electrons, causing the attracts the electrons, causing the atom to contract!atom to contract!Oxygen is the smallest of the Oxygen is the smallest of the three, Carbon is the largest.three, Carbon is the largest.

Atomic Radius decreases as we Atomic Radius decreases as we go across a period from left to go across a period from left to right and up a group.right and up a group.

ExamplesExamples

Rank the following sets in order of Rank the following sets in order of decreasing Radius.decreasing Radius.–S, Cr, Se, Sr, Ne S, Cr, Se, Sr, Ne

Sr, Cr, Se, S, Ne Sr, Cr, Se, S, Ne

–Fe, N, Ba, Ag, BeFe, N, Ba, Ag, Be Ba, Ag, Fe, Be, NBa, Ag, Fe, Be, N

Ionic Size vs. Atomic SizeIonic Size vs. Atomic Size

When an atom becomes an ion, it will When an atom becomes an ion, it will either get smaller or largereither get smaller or larger

Metals lose electrons and will get Metals lose electrons and will get smaller (stronger pull from the smaller (stronger pull from the nucleus)nucleus)

Nonmetals gain electrons and will get Nonmetals gain electrons and will get bigger (more e- to repel one another)bigger (more e- to repel one another)

Ionic Size vs. Atomic SizeIonic Size vs. Atomic Size

Which is bigger? Which is bigger? –Na or NaNa or Na++

–Cl or ClCl or Cl--

–O or OO or O-2-2

–Mg or MgMg or Mg+2+2

Ionization EnergyIonization EnergyAmount of energy required to Amount of energy required to remove a valence electron from an remove a valence electron from an atom.atom.The more stable an element is, the The more stable an element is, the harder it will be (more energy is harder it will be (more energy is required) to remove an electron.required) to remove an electron.Some elements become more Some elements become more stable by losing an electron so they stable by losing an electron so they lose electrons easily (less energy lose electrons easily (less energy needed).needed).

How does ionization energy vary How does ionization energy vary within a group (compare Li and within a group (compare Li and Na)?Na)?–The electron to be removed from Na The electron to be removed from Na

is further from the nucleus than is further from the nucleus than Lithium’s electron.Lithium’s electron.

–Sodium’s electron is held more Sodium’s electron is held more loosely and therefore easier (less loosely and therefore easier (less energy) to remove.energy) to remove.

How does ionization energy vary How does ionization energy vary across a period? (Compare across a period? (Compare elements in 3rd period)elements in 3rd period)–Sodium attains a Noble Gas Sodium attains a Noble Gas

configuration by losing an electron, configuration by losing an electron, so little energy is required.so little energy is required.

–Magnesium is somewhat stable due Magnesium is somewhat stable due to a full 3s sub-level, so more to a full 3s sub-level, so more energy is needed.energy is needed.

–Argon is a Noble Gas. Due to its Argon is a Noble Gas. Due to its stability, it is very difficult (much stability, it is very difficult (much energy needed) to remove an energy needed) to remove an electron.electron.

–Chlorine has no stability in its Chlorine has no stability in its configuration, so it is easier to configuration, so it is easier to remove an electron.remove an electron.

Ionization energy increases across Ionization energy increases across a period and up a group.a period and up a group.

ExamplesExamples

Rank the following sets in order of Rank the following sets in order of decreasing Ionization Energy.decreasing Ionization Energy.–K, Zn, Cs, Ar, PK, Zn, Cs, Ar, P

Ar, P, Zn, K, CsAr, P, Zn, K, Cs

–C, He, Ag, Pt, SnC, He, Ag, Pt, SnHe, C, Sn, Ag, PtHe, C, Sn, Ag, Pt

22ndnd Ionization Energy Ionization Energy

The 2The 2ndnd ionization energy is the ionization energy is the amount of energy required to amount of energy required to remove the second electron on the remove the second electron on the outside of an atomoutside of an atom

Sometimes it is larger than the 1Sometimes it is larger than the 1stst ionization NRG, sometimes, it is ionization NRG, sometimes, it is smallersmaller

22ndnd Ionization Energy Ionization Energy

For elements like Na and the alkali For elements like Na and the alkali metals, the 2metals, the 2ndnd ionization NRG is ionization NRG is much higher than the 1much higher than the 1stst

WHY??? WHY??? Na loses 1 e- and becomes like a Na loses 1 e- and becomes like a noble gas. noble gas. Losing the 2Losing the 2ndnd would be counter- would be counter-productive and will not happen easily! productive and will not happen easily!

22ndnd Ionization Energy Ionization Energy

For elements like Mg and the For elements like Mg and the other alkaline earth metals, the 2other alkaline earth metals, the 2ndnd ionization NRG is lower than the ionization NRG is lower than the 11stst

Losing 1 e- is relatively difficult Losing 1 e- is relatively difficult because of the sbecause of the s22 configuration configuration (somewhat stable) but losing the (somewhat stable) but losing the next e- is super easy next e- is super easy

22ndnd Ionization Energy Ionization Energy

How do you think the 1How do you think the 1stst ionization ionization NRG and the 2NRG and the 2ndnd ionization NRG ionization NRG compare for the halogens? compare for the halogens?

The Noble gases? The Noble gases?

WHY??? WHY???

ElectronegativityElectronegativityDescribes an element’s attraction Describes an element’s attraction for an electron in a covalent bond.for an electron in a covalent bond.Elements that need electrons to Elements that need electrons to complete an energy-level will have complete an energy-level will have a high electronegativity.a high electronegativity.Elements that want to lose Elements that want to lose electrons have low electrons have low electronegativities.electronegativities.

How does Electronegativity vary How does Electronegativity vary within a group? (compare F and within a group? (compare F and Cl)Cl)–Both elements need an electron to Both elements need an electron to

complete a p sub-level.complete a p sub-level.–Fluorine’s p sub-level is closer to its Fluorine’s p sub-level is closer to its

nucleus, so it has a greater nucleus, so it has a greater magnetic attraction for a free magnetic attraction for a free electron.electron.

–F has a higher electronegativity!F has a higher electronegativity!

How does electronegativity vary How does electronegativity vary across a period? (period 2)across a period? (period 2)–Fluorine benefits the most by Fluorine benefits the most by

gaining an electron, so it has the gaining an electron, so it has the highest electronegativity.highest electronegativity.

–Lithium, which wants to lose an Lithium, which wants to lose an electron has very little attraction for electron has very little attraction for an additional electron.an additional electron.

–Carbon can gain electrons but Carbon can gain electrons but sometimes loses them as well, so its sometimes loses them as well, so its electronegativity is between F and electronegativity is between F and Li.Li.

–Noble Gases have no Noble Gases have no Electronegativity!Electronegativity!

Electronegativity increases across Electronegativity increases across a period and up a group (Noble a period and up a group (Noble Gases omitted).Gases omitted).

ExamplesExamples

Rank the following sets in order of Rank the following sets in order of decreasing Electronegativity:decreasing Electronegativity:–Cu, F, Mn, Sr, SiCu, F, Mn, Sr, Si

F, Si, Cu, Mn, SrF, Si, Cu, Mn, Sr

–Al, Ca, S, Cl, FeAl, Ca, S, Cl, Fe

Cl, S, Al, Fe, CaCl, S, Al, Fe, Ca