1. The Periodic Table

2. • Introduction
– The periodic table is made up of rows of elements
and columns.
– An element is identified by its chemical symbol.
– The number above the symbol is the atomic number
– The number below the symbol is the rounded
atomic weight of the element.
– A row is called a period
– A column is called a group

3. Organizing the Elements
• Chemists used the properties of
elements to sort them into groups.
• JW. Dobreiner grouped elements into
triads.
• A triad is a set of three elements with
similar properties.

4. Mendeleev’s Periodic Table
• In 1869, a Russian
chemist and
teacher published a
table of the
elements.
• Mendeleev arranged
the elements in the
periodic table in
order of increasing
atomic mass.

5. Henry Moseley
1887 - 1915
In 1913, through his work with X-rays, he
determined the actual nuclear charge
(atomic number) of the elements*. He
rearranged the elements in order of
increasing atomic number.
*“There is in the atom a fundamental
quantity which increases by regular
steps as we pass from each element to
the next. This quantity can only be the
charge on the central positive nucleus.”

6. The Periodic Law
In the modern periodic
table elements are
arranged in order of
increasing atom ic
num ber.
Periodic Law states:
When elements are
arranged in order of
increasing atomic
number, there is a
periodic repetition
of their physical and
chemical properties.

7. • The elements can be grouped into
three broad classes based on their
general properties.
• Three classes of elements are Metals,
Nonmetals, and Metalloids.
• Across a period, the properties of
elements become less metallic and
more nonmetallic.

8. Properties of Metals
• Metals are good conductors
of heat and electricity.
• Metals are shiny.
• Metals are ductile (can be
stretched into thin wires).
• Metals are malleable (can be
pounded into thin sheets).
• A chemical property of metal
is its reaction with water
which results in corrosion.
• Solid at room temperature
except Hg.

9. Properties of Non-Metals
• Non-metals are poor
conductors of heat and
electricity.
• Non-metals are not ductile
or malleable.
• Solid non-metals are
brittle and break easily.
• They are dull.
• Many non-metals are
gases.
Sulfur

10. Properties of Metalloids
• Metalloids (metal-like) have
properties of both metals and
non-metals.
• They are solids that can be
shiny or dull.
• They conduct heat and
electricity better than non-
metals but not as well as
metals.
• They are ductile and
malleable.
Silicon

11. Groups PeriodsGroups Periods
 Columns of elements areColumns of elements are
called groups or families.called groups or families.
 Elements in each groupElements in each group
have similar but nothave similar but not
identical properties.identical properties.
 For example, lithium (Li),For example, lithium (Li),
sodium (Na), potassiumsodium (Na), potassium
(K), and other members of(K), and other members of
group IA are all soft, white,group IA are all soft, white,
shiny metals.shiny metals.
 All elements in a groupAll elements in a group
have the same number ofhave the same number of
valence electrons.valence electrons.
 Each horizontal row ofEach horizontal row of
elements is called a period.elements is called a period.
 The elements in a periodThe elements in a period
are not alike in properties.are not alike in properties.
 In fact, the propertiesIn fact, the properties
change greatly across evenchange greatly across even
given row.given row.
 The first element in a periodThe first element in a period
is always an extremelyis always an extremely
active solid. The lastactive solid. The last
element in a period, iselement in a period, is
always an inactive gas.always an inactive gas.

12. HydrogenHydrogen
 The hydrogen square sits atop group AI, butThe hydrogen square sits atop group AI, but
it is not a member of that group. Hydrogen isit is not a member of that group. Hydrogen is
in a class of its own.in a class of its own.
 It’s a gas at room temperature.It’s a gas at room temperature.
 It has one proton and one electron in its oneIt has one proton and one electron in its one
and only energy level.and only energy level.
 Hydrogen only needs 2 electrons to fill up itsHydrogen only needs 2 electrons to fill up its
valence shell.valence shell.

13. 6.2 Classifying the Elements6.2 Classifying the Elements
The periodic tableThe periodic table
displays the symbolsdisplays the symbols
and names of theand names of the
elements along withelements along with
information about theinformation about the
structure of theirstructure of their
atoms.atoms.

14.  Four chemical groupsFour chemical groups
of the periodic table:of the periodic table:
2.2. alkali metals (IA)alkali metals (IA)
3.3. alkaline earth metalsalkaline earth metals
(IIA),(IIA),
4.4. Halogens (VII),Halogens (VII),
5.5. NobleNoble gasesgases (VIIIA).(VIIIA).

15. Alkali MetalsAlkali Metals
 The alkali family is found inThe alkali family is found in
the first column of thethe first column of the
periodic table.periodic table.
 Atoms of the alkali metalsAtoms of the alkali metals
have a single electron in theirhave a single electron in their
outermost level, in otheroutermost level, in other
words, 1 valence electron.words, 1 valence electron.
 They are shiny, have theThey are shiny, have the
consistency of clay, and areconsistency of clay, and are
easily cut with a knife.easily cut with a knife.

16. Alkali MetalsAlkali Metals
 They are the mostThey are the most
reactive metals.reactive metals.
 They react violentlyThey react violently
with water.with water.
 Alkali metals areAlkali metals are
never found as freenever found as free
elements in nature.elements in nature.
They are alwaysThey are always
bonded with anotherbonded with another
element.element.

17. Alkaline Earth MetalsAlkaline Earth Metals
 They are never found uncombined in nature.They are never found uncombined in nature.
 They have two valence electrons.They have two valence electrons.
 Alkaline earth metals include magnesium andAlkaline earth metals include magnesium and
calcium, among others.calcium, among others.

18. Transition MetalsTransition Metals
 Transition ElementsTransition Elements
include those elements ininclude those elements in
the B groups.the B groups.
 These are the metals youThese are the metals you
are probably mostare probably most
familiar: copper, tin, zinc,familiar: copper, tin, zinc,
iron, nickel, gold, andiron, nickel, gold, and
silver.silver.
 They are good conductorsThey are good conductors
of heat and electricity.of heat and electricity.

19. Transition MetalsTransition Metals
 The compounds of transition metals are usually brightlyThe compounds of transition metals are usually brightly
colored and are often used to color paints.colored and are often used to color paints.
 Transition elements have 1 or 2 valence electrons, whichTransition elements have 1 or 2 valence electrons, which
they lose when they form bonds with other atoms. Somethey lose when they form bonds with other atoms. Some
transition elements can lose electrons in their next-to-transition elements can lose electrons in their next-to-
outermost level.outermost level.

20. Transition ElementsTransition Elements
 Transition elementsTransition elements have propertieshave properties
similar to one another and to other metals,similar to one another and to other metals,
but their properties do not fit in with thosebut their properties do not fit in with those
of any other group.of any other group.
 Many transition metals combineMany transition metals combine
chemically with oxygen to formchemically with oxygen to form
compounds called oxides.compounds called oxides.

21. Representative ElementsRepresentative Elements
 Groups 1A – 7A.Groups 1A – 7A.
 Elements are refered to as representativeElements are refered to as representative
elements because they display a wideelements because they display a wide
range of physical and chemical properties.range of physical and chemical properties.
 For any representative element, its groupFor any representative element, its group
number equals the number of electrons innumber equals the number of electrons in
the highest occupied energy level.the highest occupied energy level.

22. Trends in the periodicTrends in the periodic
table:table:
Ionization EnergyIonization Energy
Atomic RadiusAtomic Radius
Electron AffinityElectron Affinity
ElectronegativityElectronegativity

23. Sizes of AtomsSizes of Atoms
The bonding atomicThe bonding atomic
radius is defined asradius is defined as
one-half of theone-half of the
distance betweendistance between
covalently bondedcovalently bonded
nuclei.nuclei.

24. Atomic Radius TrendAtomic Radius Trend
 Group Trend – As you goGroup Trend – As you go down a columndown a column,,
atomic radius increases.atomic radius increases.
As you go down, eAs you go down, e--
are filled into orbitals that areare filled into orbitals that are
farther away from the nucleus (attraction notfarther away from the nucleus (attraction not
as strong).as strong).
 Periodic Trend – As you goPeriodic Trend – As you go across a periodacross a period (L(L
to R),to R), atomic radius decreases.atomic radius decreases.
As you go L to R, eAs you go L to R, e--
are put into the same orbital,are put into the same orbital,
but more pbut more p++
and eand e--
total (more attraction =total (more attraction =
smaller size).smaller size).

25. Atomic RadiusAtomic Radius

27. Ionic Radius TrendIonic Radius Trend
 MetalsMetals – lose e– lose e--
, which means more p, which means more p++
than ethan e--
(more attraction) SO…(more attraction) SO…
Ionic RadiusIonic Radius << Neutral Atomic RadiusNeutral Atomic Radius
 NonmetalsNonmetals – gain e– gain e--
, which means more e, which means more e--
than pthan p++
(not as much attraction) SO…(not as much attraction) SO…
Ionic RadiusIonic Radius >> Neutral Atomic RadiusNeutral Atomic Radius

28. Sizes of IonsSizes of Ions
 Ionic size dependsIonic size depends
upon:upon:
 Nuclear charge.Nuclear charge.
 Number ofNumber of
electrons.electrons.
 Orbitals in whichOrbitals in which
electrons reside.electrons reside.

29. Sizes of IonsSizes of Ions
 Cations areCations are
smaller than theirsmaller than their
parent atoms.parent atoms.
 The outermostThe outermost
electron iselectron is
removed andremoved and
repulsions arerepulsions are
reduced.reduced.

30. Sizes of IonsSizes of Ions
 Anions are largerAnions are larger
than their parentthan their parent
atoms.atoms.
 Electrons areElectrons are
added andadded and
repulsions arerepulsions are
increased.increased.

31. Sizes of IonsSizes of Ions
 Ions increase in sizeIons increase in size
as you go down aas you go down a
column.column.
 Due to increasingDue to increasing
value ofvalue of nn..

32. Metals versus NonmetalsMetals versus Nonmetals
 Metals tend to form cations.Metals tend to form cations.
 Nonmetals tend to form anions.Nonmetals tend to form anions.

33. BackgroundBackground
 Electrons can jump between shells (Bohr’sElectrons can jump between shells (Bohr’s
model supported by line spectra)model supported by line spectra)
 The electrons can be pushed so far thatThe electrons can be pushed so far that
they escape the attraction of the nucleusthey escape the attraction of the nucleus
 Losing an electron is called ionizationLosing an electron is called ionization
 An ion is an atom that has either a netAn ion is an atom that has either a net
positive or net negative chargepositive or net negative charge
 Q: what would the charge be on an atomQ: what would the charge be on an atom
that lost an electron? Gained two electrons?that lost an electron? Gained two electrons?
 A: +1 (because yourA: +1 (because your losinglosing a -ve electron)a -ve electron)
 A: -2 (because you gain 2 -ve electrons)A: -2 (because you gain 2 -ve electrons)

34. Ionization EnergyIonization Energy
 Amount of energy required to remove anAmount of energy required to remove an
electron from the ground state of aelectron from the ground state of a
gaseous atom or ion.gaseous atom or ion.
 First ionization energy is that energy requiredFirst ionization energy is that energy required
to remove first electron.to remove first electron.
 Second ionization energy is that energySecond ionization energy is that energy
required to remove second electron, etc.required to remove second electron, etc.

35. Ionization EnergyIonization Energy
 Group Trend – As you goGroup Trend – As you go down a columndown a column,,
ionization energy decreases.ionization energy decreases.
As you go down, atomic size is increasing (lessAs you go down, atomic size is increasing (less
attraction), so easier to remove an eattraction), so easier to remove an e--
..
 Periodic Trend – As you goPeriodic Trend – As you go across a periodacross a period (L to(L to
R),R), ionization energy increases.ionization energy increases.
As you go L to R, atomic size is decreasing (moreAs you go L to R, atomic size is decreasing (more
attraction), so more difficult to remove an eattraction), so more difficult to remove an e--
(also, metals want to lose e(also, metals want to lose e--
, but nonmetals do, but nonmetals do
not).not).

36. Ionization EnergyIonization Energy
 It requires more energy to remove eachIt requires more energy to remove each
successive electron.successive electron.
 When all valence electrons have been removed,When all valence electrons have been removed,
the ionization energy takes a quantum leap.the ionization energy takes a quantum leap.

37. Trends in First IonizationTrends in First Ionization
EnergiesEnergies
 As one goes down aAs one goes down a
column, less energycolumn, less energy
is required to removeis required to remove
the first electron.the first electron.
 For atoms in the sameFor atoms in the same
group,group, ZZeffeff is essentiallyis essentially
the same, but thethe same, but the
valence electrons arevalence electrons are
farther from thefarther from the
nucleus.nucleus.

38. ElectronegativityElectronegativity
 Electronegativity-Electronegativity-
tendency of antendency of an
atom to attract eatom to attract e--
..

39. Electronegativity TrendElectronegativity Trend
 Group Trend – As you goGroup Trend – As you go down a columndown a column,,
electronegativity decreases.electronegativity decreases.
As you go down, atomic size is increasing, so lessAs you go down, atomic size is increasing, so less
attraction to its own eattraction to its own e--
and other atom’s eand other atom’s e--
..
 Periodic Trend – As you goPeriodic Trend – As you go across a periodacross a period (L to R),(L to R),
electronegativity increases.electronegativity increases.
As you go L to R, atomic size is decreasing, so there isAs you go L to R, atomic size is decreasing, so there is
more attraction to its own emore attraction to its own e--
and other atom’s eand other atom’s e--
..

40. ElectronegativityElectronegativity