Chapter 6 Notes
1
CHAPTER 6The Periodic
Table
6.1 Organizing the Elements• Mendeleev: listed the elements in order of increasing
atomic mass and in vertical columns according to their properties.
• Left blank spaces for undiscovered elements• Predicted the properties of undisovered elements.
• Henry Moseley: determined nuclear charge (atomic number)
• Arranged the periodic table by order of atomic number
Significance of Subatomic Particles
Protons: Define each atomElectrons: Determines the properties of atomsNeutrons: only alters the mass of an atom
Periodic Organization• 7 horizontal rows: periods Periods correspond to the principal energy level of atoms (Principal = Outer)
• Vertical columns: families/groups Corresponds to the number of outer energy level electrons
Chapter 6 Notes
2
The Periodic LawWhen the elements are arranged in order of increasing atomic number, there is a periodic pattern in their physical and chemical properties
• Metals: good conductors of heat and electric current
• Nonmetals: poor conductors of heat and electric current
• Metalloids: properties of both. It depends on the conditions
3 Classes of Elements
• About 80% of periodic table.• High sheen and can reflect light.• Most are ductile (make wires)• Most are malleable and can be
made into thin sheets.
Metals
(Malleable = Bend)
NonMetals• Most are gases at room temperature.• Bromine is a red liquid• Solid nonmetals are brittle.• Have a large variation of properties
Chapter 6 Notes
3
• 1A: Alkali metals• 2A: Alkaline earth metals • 7A: Halogens• 8A: Noble Gases
6.2 Classifying the Elements
Configurations of the Groups Valence Electrons
• Electrons in “s” and “p” orbitals of outer energy level only.
• Show a pattern in the group.• Increase across a period.
• s1=1 Valence electron• Very reactive• Rarely found alone (always bonding)
Alkali Metals Group 1A
• Found in the crust of the earth.
Alkaline Earth MetalsGroup 2A
s2 = 2 valence electrons
Chapter 6 Notes
4
ELECTRON CONFIGURATIONS IN GROUPS
• There is a relationship between electron configuration of an element and its placement on the periodic table
Blocks of Periodic Table
• Can bond with almost any nonmetal because it is willing to give up many electrons.
Transition Metals
d block
Group B • s, p, d, f blocks• The location of elements within these blocks corresponds to the number of electrons in the outermost energy level
Halogens (7A)
F: 1s22s22p5
Cl: 1s22s22p63s23p5
Group (6A)
O: 1s22s2 2p4
S: 1s22s22p63s2 3p4
Chapter 6 Notes
5
Alkali Metals (1A)Na: 1s22s22p63s1 (No 3p)
K: 1s22s22p63s23p64s1(No 4p)
Alkali Earth Metals (2A)Mg: 1s22s22p63s2 (No 3p)
Ca: 1s22s22p63s23p64s2 (No 4p)
Noble Gases
• Outermost “s” and “p” sublevels are completely filled (Inactive)
• Filled outer levels make atoms stable and inactive.
Group 8A
s2p6 = 8 valence electrons
Valence Electrons• Electrons in the last energy level
of an atom.• Include electrons in “s” and “p”
orbitals only.• Show a pattern in the group.• Increase across a period.
Representative Elements
• Outermost “s” or “p” sublevels are only partially filled (Group A elements)
• Represents elements from metals to nonmetals.
• Reactive Elements• 8A not representative elements
1A-7A• For any representative element, the group number is equal to the number of valence electrons.
• Groups 1A – 7A.
Chapter 6 Notes
6
1A: s1 = 1 valence electrons2A: s2 = 2 valence electrons3A: s2p1 = 3 valence electrons4A: s2p2 = 4 valence electrons5A: s2p3 = 5 valence electrons6A: s2p4 = 6 valence electrons7A: s2p5 = 7 valence electrons8A: s2p6 = 8 valence electrons
1A 8A 3A 7A 6A 5A 4A 2A
Group B Elements
Transition Metals: (Group B)
• outermost “s” sublevel and the nearby “d” sublevel contain electrons
• All transition metals usually have the same number of valence electrons.
Group B = Valence Electrons Do NOT determine properties
1A 8A 3A 7A 6A 5A 4A 2A
Group B Elements
Sc: [Ar] 4s2 3d1Fe: [Ar] 4s2 3d6Zr: [Kr] 5s2 4d2
• 2 valence electrons• Their properties are determined by the
electrons in the “d” sublevel.
Transition MetalsInner Transition metals
outermost “s” sublevel and the nearby “f” sublevel generally contain electrons
Chapter 6 Notes
7
Movement of Electrons1A: 1 lost easily2A: 2 lost easily3A: 3 lost easily5A: 3 gained6A: 2 gained7A: 1 gained
Why do atoms form ions?
Representative elements form ions to attain the electron configuration of a noble gas.
Why do atoms form ions?
Remember, as long as the proton numbers stays the same, the atom does not change. The electron number can change to attain the electron configuration of a noble gas.
P = 10N = 10 P = 11N = 12
Neon vs. Sodium
1s2 2s2 2p6 1s2 2s2 2p6 3s1
P = 10N = 10
P = 7N = 7
Neon vs. Nitrogen
1s2 2s2 2p6 1s2 2s2 2p3
Ions for the groups Group 1A:
Group 2A:
Group 3A:
Group 5A:
Group 6A:
Group 7A:
Chapter 6 Notes
8
Charges of Atoms1A: 1+2A: 2+3A: 3+5A: 36A: 27A: 1
BEFORE
• Na: 1s2 2s2 2p6 3s1• (Will lose 1 electron)
• B: 1s2 2s2 2p1• (Will lose 3 electrons)
• P: 1s2 2s2 2p6 3s2 3p3• (Will gain 3 electrons)
• F: 1s2 2s2 2p5• (Will gain 1 electron)
AFTER
• Na: 1s2 2s2 2p6• ( Electron Configuration of Neon, Na +)
• B: 1s2• ( Electron Configuration of helium, B 3+)
• P: 1s2 2s2 2p6 3s2 3p6• ( Electron Configuration of Argon, P 3)
• F: 1s2 2s2 2p6• ( Electron Configuration of Neon, F )
Li
Cl
F
# valence Gain or Lose # electrons Noble Gas Charge
electrons electrons? gained/lost
6.3 PERIODIC TRENDS • The properties of all atoms follow trends. These trends can be easily understood by using the periodic table.
• Trends go according to groups and periods.
Nuclear Charge• Proton Number• Increases as atomic number increases. (Protons increase!)
• As proton number increases, the overall positive charge of the nucleus increases.
Chapter 6 Notes
9
1A 8A 3A 7A 6A 5A 4A 2A
Group B Elements
Shielding Electrons• Electrons between the nucleus and the valence electrons.• They shield the valence electrons from the force of the nucleus.
• Na: 10• S: 10• Li: 2• N: 2
Shielding Electrons
Shielding Electrons• Total Electrons – Valence Electrons• Sodium:• Total Electrons = 11• Valence Electrons = 1• Shielding Electrons = 10
• Sulfur:• Total Electrons = 16• Valence Electrons = 6• Shielding Electrons = 10
SE = ____________
ENC = Total Shielding
SE = ____________
ENC = Total Shielding
Shielding Electrons• Total Electrons – Valence ElectronsAluminum:• Total Electrons = 13• Valence Electrons = 3• Shielding Electrons = 10Nitrogen:• Total Electrons = 7• Valence Electrons = 5• Shielding Electrons = 2
SE = ____________
ENC = Total Shielding
SE = ____________
ENC = Total Shielding
Na11 Protons
2 e8 e1 e
P = 10N = 10
1s2 2s2 2p6 Total Electrons- Valence Electrons
Shielding Electrons
ENC=
Chapter 6 Notes
10
P = 11N = 12
1s2 2s2 2p6 3s1 Total Electrons- Valence Electrons
Shielding Electrons
ENC=
P = 15N = 16
1s2 2s2 2p6 3s2 3p3 Total Electrons- Valence Electrons
Shielding Electrons
ENC=
1s2 2s2 2p6 3s2 3p6 4s1 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3
Potassium
Total Electrons =
Valence Electrons =
Shielding Electrons=
ENC =
Arsenic
Total Electrons =
Valence Eelctrons =
Shielding Electrons =
ENC =
Shielding Effect• The further an energy level is from the nucleus, the more it is shielded from the attraction to the nucleus.• The outer energy level is shielded by the inner energy levels.• Atoms with more energy levels are larger.
Effective Nuclear Charge• Nuclear Charge Shielding Electrons• The nuclear charge that the valence
electrons actually feel.
• As the effective nuclear charge increases, the size of the atom decreases because the nucleus has more pulling power on the outer energy level of the atom.
Effective Nuclear ChargeFluorine Atom:• 9 protons & 9 electrons• Valence electrons: 7• Shielding electrons: 2• Effective Nuclear Charge = +7
Nuclear Charge (9) Shielding Electrons (2)
Chapter 6 Notes
11
Effective Nuclear ChargeCarbon Atom:• 6 protons & 6 electrons• Valence electrons: 4• Shielding electrons: 2• Effective Nuclear Charge = +4
Nuclear Charge (6) Shielding Electrons (2)
+7
Nuclear Charge:______
Total Electrons:______
Valence Electrons: _____
Shielding Electrons:_____
ENC:______
+1
+1
+1
+1
+1
+5+2+1
+1
+3 +4 +6
+6
+6
+6
+6
ENC vs. Energy Level
+7 +8
+7
+7
+7
+7
+5
+5
+5
+8+4+2 +3
+2
+2
+2
+2
+3
+3
+3
+4
+4
+4
+8
+8
+8
+5
1
7
6
54
32
Large atoms have more shielding electrons and are further away from nucleus. So, there is less pull on the valence electrons of a large atom than a small atom.
What if 2 atoms have the same ENC? Effective Nuclear Charge
• ENC = # Valence Electrons• The greater the ENC, the more the nucleus pulls on the outer energy level.
Chapter 6 Notes
12
Atomic Size/Radius• Radius of an atom cannot be measured directly because you cannot see the outer electrons to measure the radius.
• Measured in picometers (1012)
Measuring Atoms• Half the distance between the nuclei of two like atoms is the atomic radius
Measure from nucleus to nucleus
and take half
ENC+3
ENC+7
Aluminum vs. Chlorine(Outer Energy Level Only)
Both atoms have 3 energy
levels, but chlorine's outer level
shrinks due to the high ENC.
Atomic Size/Radius (cont.)• Increases to the left and down.• More energy levels increases the size of the atom.
• Large ENC makes a small atom because there is more pull on outer energy level.
Atomic Size/Radius (cont.)• Atoms with more energy levels are
larger, regardless of ENC.• For example...Iodine vs. Lithium
Iodine Lithium
ENC = +7
5 energy levels
ENC = +1
2 energy levels
Chapter 6 Notes
13
Atomic Size/Radius (cont.)
• High ENC atoms shrink because the the outer level is pulled very close to the nucleus.
• Low ENC atoms are large because the nucleus has little pulling power on the outer energy level.
Comparing 2 atoms in the same period
Group Trends• Atomic size generally increases as you move down a group of the periodic table
• Shielding increases for outer levels because there are more inner energy levels.
(More energy levels)
Periodic Trends• Atomic size decreases as you move from left to right across a period because the proton number increases.
• Shielding is constant because atoms do not gain energy levels across a period.
(ENC increase)
IONSAn ion is an atom or group of atoms that has a positive or negative charge
CATION: Positive Ions (Mg 2+)• Lost one or more electrons
ANION: Negative Ions (S 2)Gained one or more electrons
Magnesium
1s2 2s2 2p6 3s2
Will lose 2 electrons.
Mg 2+
Atom shrinks
Protons vs. Electrons
12vs.10
Sulfur
1s2 2s2 2p6 3s2 3p4
Will gain 2 electrons.
S 2
Atom expands
Protons vs. Electrons
16vs.18
TRENDS IN IONIC SIZE• Cations are always smaller than their neutral form• They can lose an energy level which decreases shielding.• Electrons lose the “tug of war” with the protons.
• This is because the loss of outer shell electrons results in increased attraction by the nucleus for the fewer remaining electrons.
• Cations decrease across period
Chapter 6 Notes
14
TRENDS IN IONIC SIZE
• Anions are always larger than the atoms from which they are formed.
• Electrons win the “tug of war” with the protons because the effective nuclear attraction for the
nucleus is less when the number of electrons increases
• Anions decrease across period
ANIONS• Larger than neutral version.• Negatively Charged• Gain Electrons• Nonmetals
More they gain,bigger they get.
CATIONS• Smaller than neutral version.• Positively Charged• Lose Electrons• Metals More they lose,
smaller they get.
Which is a smaller ion?Boron: 1s2 2s2 2p1
Aluminum:1s2 2s2 2p6 3s2 3p1
Which is larger?Oxygen: 1s2 2s2 2p4
Oxygen Ion:1s2 2s2 2p6
Ionic ChargesNoble Gas Element Charge
He: 1s2 Ca: 1s2 2s2 2p6 3s2 3p6 4s2
Ne: 1s2 2s2 2p6 N: 1s2 2s2 2p3
Ar: 1s2 2s2 2p6 3s2 3p6 Al: 1s2 2s2 2p6 3s2 3p1
Kr: [Ar] 4s2 4p6 S: 1s2 2s2 2p6 3s2 3p4
TRENDS IN IONIZATION ENERGY• The energy that is required to overcome the
attraction of the nuclear charge and remove an electron from an atom.
Weak Pull =
Strong Pull =
Low ENC =
High ENC =
Low IE
High IE
Chapter 6 Notes
15
Ionization Energy(cont.)• Increases right and up.• Hard to remove electrons from atoms with outer energy level close to nucleus.
• Hard to remove electrons when the ENC is large.
1st IONIZATION ENERGY• The energy required to remove the first
electron from an atom.• Depends on how many electrons exist in
the outer energy level. • See table 6.1 on page 173.
TRENDS IN IONIZATION ENERGY3 Things determine whether electrons can be removed...
1. ENC (effective nuclear charge)2. The number of energy levels3. The Tug of War after electrons have been removed
1st, 2nd, & 3rd Ionization Energy
Na: 1s2 2s2 2p6 3s1 Remove 1 Remove 2 Remove 3
Mg: 1s2 2s2 2p6 3s2 Remove 1 Remove 2 Remove 3
Al: 1s2 2s2 2p6 3s2 3p1 Remove 1 Remove 2 Remove 3
2nd IONIZATION ENERGYEnergy required to remove the second electron from an atom.
Depends on how many electrons exist in the outer energy level.
Chapter 6 Notes
16
2nd IONIZATION ENERGY
It always requires more energy to remove the second electron than it does to remove the first.
Element First Second Third Fourth Fifth Sixth Seventh
Na 496 4,560
Mg 738 1,450 7,730
Al 577 1,816 2,881 11,600
P 1,060 1,890 2,905 4,950 6,270 21,200
S 999.6 2,260 3,375 4,565 6,950 8,490 27,107
Cl 1,256 2,295 3,850 5,160 6,560 9,360 11,000
Ar 1,520 2,665 3,945 5,770 7,230 8,780 12,000
Group Trends• Ionization energy decreases
as you move down a group• Li > Na > K
Periodic Trends• Ionization energy generally increases as you move from left to right across a period due to the number of protons increasing.
TRENDS IN ELECTRONEGATIVITY
• The electronegativity of an element is the tendency for the atoms of the element to attract electrons when they are chemically combined with another element
http://green-planet-solar-energy.com/support-files/pt-elecneg-download.pdf
Chapter 6 Notes
17
Electronegativity.(cont.)• Increases right and up.• Closer outer energy levels attracts electrons more.
• Larger ENC attracts electrons more easily because the pull from the nucleus is greater.
• Each element is assigned an electronegativity value
• As you move across the periodic table the electronegativity increases
• Electronegativity decreases as you move down a group
Period
Density
% Error = ____________________ x 100Predicted AcceptedAccepted
Group 7ADensities
F: 1.7Br: 3.12At: 9.87
Cl = 3.2
2 Factors determine most trends1. ENC• Size• Electronegativity• Ionization Energy2. Principal Energy Level• Size• Shielding Electrons• Attraction of valence electrons to the nucleus
+1 Weak Pull
+7 Strong Pull
(Periodic Trends)
(Group Trends)
+1 +6 Metal NonMetal
Which atom will attract the free electron?
Which has the higher electron affinity?
Chapter 6 Notes
18
Know these 7 Trends• ENC• Nuclear Charge• Atomic Size (Atomic Radii)• Shielding Electrons• Ionization Energy• Electronegativity• Ionic Size
What makes an atom large?
1.
2.
What makes an atom small?
1.
2.
What gives an atom a strong ENC?
1.
2.
What gives an atom a weak ENC?
1.
2.
What give an atom High Electronegativity?
1.
2.
What gives an atom Low Electronegativity?
1.
2.
Which atoms have High Ionization Energy?
1.
2.
Which atoms have Low Ionization Energy?
1.
2.
Possible Matching TermsElectronegativityNuclear ChargeTransition MetalsInner Transition MetalsEffective Nuclear ChargeIonization EnergyShielding ElectronsAlkali MetalsAlkali Earth MetalsPeriodic LawAtomic SizeCationAnion
PeriodGroupValence ElectronsNoble GasesHalogensMendeleevp blockd blocks blockf blockGroup TrendMoselyPeriodic Trend
• Summary of all trends is on Page 178.
• You must memorize all trends for the test!
Attachments
key_Configurations of the Groups.pdf
Name ___________________________________________ Hour ______
Configuration of the Groups
For each element, put the last energy level, sublevel, and number of electrons for that element on the periodic table.
You must do the electron configurations on the back before completing the front! (You may use abbreviated method!)
H
1s1
He
1s2
Li
2s1
Be
2s2
B
2p1
C
2p2
N
2p3
O
2p4
F
2p5
Ne
2p6
Na
3s1
Mg
3s2
Al
3p1
Si
3p2
P
3p3
S
3p4
Cl
3p5
Ar
3p6
K
4s1
Ca
4s2
Sc
3d1
Ti
3d2
V
3d3
Cr
3d4
Mn
3d5
Fe
3d6
Co
3d7
Ni
3d8
Cu
3d9
Zn
3d10
Ga
4p1
Ge
4p2
As
4p3
Se
4p4
Br
4p5
Kr
4p6
1. Look at the information you have put in each block. What are the similarities of the elements in each column? Explain your answer.
2. Look at the information you have put in each block. What are the similarities of the elements in each row? What does this mean?
Example:
Be
2s2
Answer Key
SMART Notebook
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