Chapter-5
1
The Periodic Table
Chapter 5
Chapter-5 2
Chapter-5 3
Periodic Poem
Each element has a spot on the Periodic Table,
Whether metal or gas, radioactive or stable.
You can find out its number, its symbol, its weight,
And from its position, its physical state.
Elements lined up in columns and rows,
The reason for this order, as each chemist knows,
Is that atoms are made up of still smaller bits,
(Figuring this out tested scientists' wits!).
In the nucleus, protons and neutrons are found,
And a cloud of electrons is buzzing around.
First take one proton, put in its place;
Now you have hydrogen, the simplest case.
Add two neutrons and one more proton,
And suddenly, the hydrogen's gone!
Now you have helium, quite different stuff ...
You get the picture; I've said enough.
These tiny particles: they're like building blocks
That make people and buildings, flowers, and rocks.
They create all of the elements we find
In everyday things of every kind!
Chapter-5 4
1789 - Lavoisier
Acid making
phosphorous
sulfur
carbon
Gas like
light
heat
oxygen
Azote (nitrogen)
hydrogen
Chapter-5 5
1789 - Lavoisier
Metallic
Copper, nickel, iron
Cobalt, mercury, tin
Gold, lead, silver, zinc
Earthy
Lime (calcium hydroxide)
Magnesia (magnesium oxide)
Manganese, tungsten
(platina) platinum
Barytes (barium sulphate)
Argilla (Aluminum oxide)
Silex (silicon dioxide)
Chapter-5 6
Development of the Modern Periodic Table
1. Compiled a list of 23 elements known at the time.
2. 1800’s changes in the world
3. Electricity to break compounds, spectrometer, industrial revolution
4. Tripled Lavoisier’s number of elements
5. 1860 chemists agreed on atomic masses
A. Lavoisier – 1790’s
Chapter-5
2
Chapter-5 7
B. John Newland - 1864
1. Proposed an organization scheme
2. Arranged by increasing atomic mass
3. The elements properties repeated every eighthelement
4. The law of octaves.
John Newlands arranged the first 16 known elements and called it “ Law of Octaves”.
Chapter-5 8
Chapter-5 9
Stanislao Cannizzaro: proposed method to measure standard relative atomic masses
In 1869, Dmitri Mendeleev and Lothar Meyerindependently proposed the Periodic Law:
• Meyer based his periodic law on the property called atomic volume:
The periodic law states that when the elements are arranged in the order of increasing atomic mass, their physical and chemical properties vary periodically.
Atomic volume (cm3/mol) =Molar mass (g/mol)
d (cm3/g)
C. Cannizzaro, Meyer, Mendeleev
Chapter-5 10
C. Cannizzaro, Meyer, Mendeleev
Meyer & Mendeleev each demonstrated connections between atomic mass and elemental properties.
Mendeleev published first and showed the connections usefulness.
Mendeleev arranged the PT using atomic mass and their physical and chemical properties.
He predicted the existence and properties of undiscovered elements.
He left blanks for undiscovered elements. Can you find errors in his system?
Chapter-5 11
Based on Atomic Mass
Chapter-5 12
Mendeleev’s First Periodic Table
"I saw in a dream a table where all elements fell into place as required. Awakening, I immediately wrote it down on a piece of paper, only in one place did a correction later seem necessary."— Mendeleev, as quoted by Inostrantze
Chapter-5
3
Chapter-5 13
British chemist - discoveries resulted in a more accurate positioning of elements by determination of atomic numbers.
(Tragically for the development of science, Moseley was killed in action at Gallipoli in 1915).
D. Henry Moseley, 1913
Chapter-5 14
When atoms were arranged according toincreasing atomic number, the few problems with Mendeleev's periodic table had disappeared. Because of Moseley's work, the modern periodic table is based on the atomic numbers of the elements
Periodic Law: There is a periodic repetition of the chemical and physical properties of the elements when they are arranged by increasing atomic number.
D. Henry Moseley, 1913
Chapter-5 15
E. William Ramsay
Mendeleev did not anticipate the noble gases. He left no blanks for them.
William Ramsay discovered them.
Chapter-5 16
QUESTION:
Are there other periodic tables ?
Try to find:Carbon
Chapter-5 17 Chapter-5 18
Chapter-5
4
Chapter-5 19 Chapter-5 20
Chapter-5 21 Chapter-5 22
Chapter-5 23
How Diverse is Our Periodic Table?
Chapter-5 24
Periodic Table Song:https://www.youtube.com/watch?v=zUDDiWtFtEM
Chapter-5
5
Chapter-5 25
7 periods → arranged in order of increasing atomic number18 groups → each group has similar properties
Groups (vertical)Periods(horizontal)
Periodic Table of the ElementsBased on Atomic Numbers1
2
3
4
5
6
7
Chapter-5 26
Valence Electrons
1. electrons in the highest principal energy level
2. What would group IA look like?
3. Atoms in the same group have similar chemical properties because they have the same number of valence electrons.
The s-, p-, d- and f- block elements
1s1, 2s1….
Classification of the Elements
Chapter-5 27
Classification of the Elements
Chapter-5 28
For convenience f-block elements are pulled out of the 6th and 7th period.
If f-block Elements were in 6th and 7th Periods
Chapter-5 29
Metal –Metalloid – Nonmetal
Chapter-5 30
Elements in Our Daily Life
Solids:
• Carbon, sulfur
• Copper, iron, gold
Liquids: There are only 2 liquids at room temperature!
• Mercury
• Bromine
Gases:
• Oxygen, hydrogen, nitrogen
• Argon, neon, helium
Chapter-5
6
Chapter-5 31
Main Group elements
Inner-transitionelements
Transition elements
Chapter-5 32
s and p block elements are known as Main Group Elements
The electron configurations of the elements in each main group are regular and consistent: same group elements have same number of valence electrons.
•Group-1 : 1 valence e–
•Group-7 : 7 valence e–
•Group-8 : 8 valence e–
Chapter-5 33
Alkali Metals
Transition Metals
Alkaline-Earth Metals Halogens
Noble Gases
Lanthanides and Actinides
Chapter-5 34
Your Turn: Label all groups on the Periodic Table
Chapter-5 35
KEY
HydrogenMetalloids
Chapter-5 36
Properties of Metals, Metalloids and Nonmetals
Chapter-5
7
Chapter-5 37
Properties of Metals
Metals are:
•Good conductors of heat and electricity
•Malleable
•Ductile
•High luster
•All solids except mercury
•High tensile strength
•
Chapter-5 38
Properties of Metalloids
Metalloids have properties of both metals and nonmetals!
They are:
• More brittle than metals but less brittle than most nonmetallic solids
• Semiconductors of electricity
• Some posses metallic luster
Chapter-5 39
Silicon – A Metalloid
Other metalloids include:
Boron, B Germanium, GeArsenic, AsAntimony, Sb Tellurium, Te
metallic lusterbrittle like a nonmetala semiconductor
Chapter-5 40
Properties of Nonmetals
Nonmetals are:
• Poor conductors of heat and electricity
• Tend to be brittle
• Solid, liquid (Br2) but mostly gases at room temp.
Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element.
Chapter-5 41
Other Nonmetals
Sulfur, S, was once known as “brimstone”
Microspheres of phosphorus, P, a reactive nonmetal
Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure
Chapter-5 42
s-block Elements: Group 1A & 2A
Chemically reactive metals, group 1 more reactive than group 2
•Has one valance electron, thus extremely reactive!
Alkali metals:
• Silvery appearance
• Soft enough to cut with a knife
• NOT found in nature as free elements
• Typically have lower mp than transition metals
• Hydrogen shares e-configuration but NOT the properties
Chapter-5
8
Chapter-5 43
s-block Elements: Group 1A
Li Na K
Reactivity of Alkali Metals Chapter-5 44
s-block Elements: Group 2A
Alkaline-earth metals:
• Has two valence electrons, thus very reactive
• Harder, denser, stronger than group-1
• Have a higher melting point than group-1
• Too reactive to be found uncombined in nature
• Helium shares e- configuration but NOT properties
Chapter-5 45
s-block Elements: Group 2A
Alkaline-earth metals:
• The word “alkaline” means “basic”➢ Common bases include salts of metals:
NaOHCa(OH)2
Mg(OH)2
Ca(OH)2
Mg(OH)2
Chapter-5 46
p-block Elements: Group 13A-18A
Includes:
metals, metalloids, and nonmetals
Noble Gases: least reactiveHalogens: most reactive nonmetals• Vigorous reaction with most metals to form salt• Halogen means “salt maker” in ancient Greek
Chapter-5 47
p-block Metals: Group 13A-16A
p-block metals are generally:•harder & denser than s-block•but softer & less dense than d-block metalsFound in nature solely as compounds except for bismuth
Chapter-5 48
p-block Metalloids: Group 13A-16A
Metalloids have properties of both metals and nonmetals!
They are:
• More brittle than metals but less brittle than most nonmetallic solids
• Semiconductors of electricity
•Some posses metallic luster
Chapter-5
9
Chapter-5 49
p-block Nonmetals: Group 13A-18A
Sulfur Phosphorous
Carbon
Iodine
yellow red violet black
White phosphorus, or yellow phosphorus (P4)White phosphorus is a translucent waxy solid that quickly becomes yellow when exposed to light
Chapter-5 50
p-block Nonmetals: Group 17A
Cl2 Br2 I2
Br2
Cl2
I2
F2 is a highly reactive and toxic gas
Chapter-5 51
Halogens: Group 17A
Halogens:•have 7 valence electrons•are never found pure in nature; they are too reactive!
•in their pure form are diatomic molecules: (F2, Cl2, Br2, and I2)• F2: pale-yellow gas• Cl2: yellow-green gas• Br2: brown liquid (with brown vapor)• I2: metallic solid (with purple vapor)
Chapter-5 52
Noble Gases: Group 18A
have 8 valence electrons (except Helium 2e- )are monoatomic gases ONLY found pure in nature.colorless, odorless and unreactive; they were among the last of the natural elements to be discoveredhave astronomical ionization energieshave positive electron affinities•Because, they are relatively unreactive!
Chapter-5 53
Noble Gas Compounds?
Xe forms three compounds:
•XeF2
•XeF4 (at right)
•XeF6
Kr forms only one stable compound:•KrF2
The unstable HArF was synthesized in 2000.
Crystals of XeF4
Chapter-5 54
d-block elements: Group 3B-12B
Transition Metals
Copper, Cu, is a relatively soft metal, and a very good electrical conductor.
Mercury, Hg, is the only metal that exists as a liquid at room temperature
Chapter-5
10
Chapter-5 55
d-block elements: Group 3B-12B
Transition Metals:Less reactive than s block, many existing in nature as free elements.Electrons added to the d sublevel of the preceding energy level (n-1).
Electron configuration: (n-1) d1-10 ns 0-2
Some deviations from orderly d sublevel filling occur in group 4-11(s electrons jumping to d sublevel)They often form colored compounds and have multiple oxidation states
Chapter-5 56
f-block elements
Lanthanides and Actinides:
are wedged between groups 3B and 4B in the 6th and 7th period
mostly radioactivetrans-Uranium elements are all synthetic
Electron configuration: ns 0-2 (n-1) d 0-1 (n-2)f 1-14
Chapter-5 57
Glenn Seaborg (1912 – 1999)(UC Berkeley, 1944)
Development and arrangement of the Actinides
Discovery of transuranium elements
f-block elements
Chapter-5 58
Periodic Trends
Certain trends of each element determine its location in the periodic table:
Metallic/nonmetallic
Radius:
Atomic radius
Ionic radius
Ionization energy
Electron affinity
Electronegativity
Melting & boiling point
•Energy levels or shells: n
•Effective nuclear charge: Zeff
•Electron shielding
Chapter-5 59
Effective Nuclear Charge
Zeff is found this way:
Zeff = Z − S
S: usually close to the number of inner electrons
atomic number shielding
Electron Shielding:https://www.youtube.com/watch?v=V_LpZkDM360
Effective Nuclear Charge:https://www.youtube.com/watch?v=U0M6AHV52mk
Chapter-5 60
Sizes of Atoms and Ions
Half of the distance between two nuclei (in covalently bonded diatomic molecule)
Chapter-5
11
Chapter-5 61
Sizes of Atoms
Chapter-5 62
Period Trend:Atomic Radius
Chapter-5 63
Cations are smaller than their parent atoms
6.3
Treat electrons as pounds!
Lose electron → Form cation → Get smaller!
Chapter-5 64
Cations are smallerthan their parent atoms
Electrons are removed Zeff increased thus size gets smaller.
Chapter-5 65
Treat electrons as pounds!
Gain electron → Form anion → Get bigger!
Anions are bigger than their parent atom
Chapter-5 66
Anions are bigger than their parent atoms
Electrons are added Zeff decreased thus size gets bigger.
Chapter-5
12
Chapter-5 67
Within an isoelectronic group of ions, the one with the greatest nuclear charge will be the smallest.
•Note that they all have:•Different elements but have same number of electrons!
•Which one has the largest ionic radii?
•For example, look at the ions listed below.
All have 18 electrons
Isoelectronic Series
P3– S2– Cl– Ar K+ Ca2+
Chapter-5 68
Sizes of Atoms and Ions
Arrange the following in decreasing size: N, N2–, N3–
N3– > N2– > N
Arrange the following in decreasing size: Ca, Ca+, Ca2+
Ca > Ca+ > Ca2+
Arrange the size of these ions in the ascending order:
Sr+2 As3− Se2− Rb+ Br−
Sr+2 > Rb+ > Br− > Se2− > As3−
Chapter-5 69
A (g) + energy –> A+ (g) + e-
The process is endothermic!
Ionization Energy
Ionization Energy is energy required to remove an electron from the ground state of a gaseous atom or ion. First ionization energy: energy required to remove
first electron.
Second ionization energy: energy required to remove second electron, etc.
Smaller the IE easier to remove electron!Chapter-5 70
It requires more energy to remove each successive electron.
When all valence electrons have been removed, the ionization energy takes a quantum leap.
Ionization Energy
Chapter-5 71
Ionization energy increases
Chapter-5 72
Electron affinity is the energy release when an electron is added to a neutral atom in the gaseous state:
•For a fluorine atom, the first electron affinity is illustrated by:
•When F gains an electron, energy is released. The process is exothermic!
F(g) + e- → F-(g) EA = -328 kJ
F(1s22s22p5) + e- → F-(1s22s22p6)
Electron Affinity
Chapter-5
13
Chapter-5 73
Greater (-) value More stable atom A happy atom Higher electron affinity
Electron affinity increases
Chapter-5 74
Electronegativity
Electronegativity is a numerical value that shows the ability of an atom to attract electrons to itself in a chemical bond.
Fluorine, the most electronegative element, is arbitrarily assigned a value of 4.0. Values for other elements are calculated compared to Fluorine.
The most electronegative atoms are:
F O N
Chapter-5 75 Chapter-5 76
Atomic radius
Ato
mic
rad
ius
Electron affinity
Ele
ctro
n af
fini
ty
Ionization energy
Ioni
zatio
n en
ergy
Atomic Radius
Electron Affinity
Ionization Energy
Metallic/Nonmetallic Character
Electonegativity
Electronegativity
Ele
ctro
nega
tivity
Chapter-5 77
Summary of Periodic Trends
Atomic radius decreaseIonization energy increaseElectron affinity increaseElectronegativity increase
Chapter-5 78
Melting and Boiling Points
Instead of a generally increasing or decreasing trend, melting and boiling points reach two different peaks as d and p orbitals fill.