The student will investigate and understand that the placement of elements on the periodic table is a function of their atomic structure The periodic table is a tool used for the investigations Key Concepts ID: 614714
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Virginia Standard: CH. 2a-cThe student will investigate and understand that the placement of elements on the periodic table is a function of their atomic structure. The periodic table is a tool used for the investigations.Key Concepts:a. families or groups;b. series and periods;c. trends including atomic radii, electronegativity, shielding effect, and ionization energy
Periodic Table
SOL: CH.2d,e,f
Textbook pages 154-178
Workbook pages 51-57Slide2
Forerunners to the Periodic Table(Dobereiner)
30 elements had been discovered by late 1700.
In 1800 scientist were using lab techniques to discover additional elements.
It took less than 100 years for the number of elements discovered to double.Johann Wolfgang (J.W.) Dobereiner classified elements into groups of three.Classification was called triads.The elements in the triad were grouped together because they had similar chemical properties.Chlorine, Bromine, and Iodine is one set of triads.
www.uv.es/~bertomeu/material/clasico/dober.jpgSlide3
Forerunners to the Periodic Table(Newland)John A.R. (J.A.R.) Newland- arranged elements by
increasing atomic mass
.
Arrangement called Law of Octaves because he noticed that the chemical properties started to repeat after the 8th element.Scientist disliked the name elected for the arrangement so his ideas were rejected.Slide4
Forerunners to the Periodic Table(Meyer and Mendeleev)Lothar Meyer and Dmitri Mendeleev published almost identical arrangements for elements.
Since
Mendeleev
’s was published first and he was better at explaining the uses for his table he is credited with developing the 1st Periodic Table.Mendeleev made correct predictions about properties for several undiscovered elements. (Ekasilicon) Eka meaning one.Slide5
Forerunners to the Periodic Table(Mendeleev)Started his arrangement to help his students learn about elements.
Elements with similar properties were on the same row. New column started to keep elements with similar properties together.
In order to keep elements like tellirium (Te) and iodine (I) on the same row, with elements that have the similar properties, he had to ignore his rule to arrange
ALL elements by increasing atomic mass.He wasn’t able to explain why some elements didn’t follow the increasing atomic mass order.Slide6
Forerunners to the Periodic Table(Moseley)Henry
Moseley
discovered that no two elements have the same number of protons (atomic #).
Arranged elements by increasing atomic # not increasing atomic mass like Mendeleev, Meyer and Newland.This arrangement known as the Modern Periodic Table and it the arrangement used currently. This arrangement solved Mendeleev’s problem.Slide7
Modern Periodic TablePeriodic Law -when elements are arranged by increasing atomic number there is a periodic repetition of their physical and chemical properties.(fig. 6.1 page 155).
Over 100 elements on table.
Each period, row, corresponds to a main energy level in the quantum mechanical model of the atom.
All elements in the same column have similar properties and are referred to as a group or family. However, as you move across the period from left to right the properties change. Slide8
Reading the Periodic table(Metal, Nonmetals, Metalloids)
Notice:
groups are numbered using Arabic numbers 1-18. This is IUPAC (International Union of Pure and Applied Chemistry) labeling method. IUPAC is an organization that sets standards for Chemistry.Slide9
Reading the Periodic Table(Metals, Nonmetals, Metalloids)Metals are good conductors of heat and electricity. They ductile and malleable. Mercury only metal that is not a solid at room temperature.
Nonmetals
are not good conductors of heat or electricity. They can be solid, liquid, or gas at room temperature. Wide variation in their properties.
Metalloids (semimetals) have properties similar to metal and nonmetal.Slide10
Reading the Periodic Table(Group Names & Physical State)
United State group labelling method similar to one displayed.
However Arabic # used not Roman Numeral.Slide11
Reading the Periodic Table
11
Na
Sodium
22.990
Atomic
Number
Element
Symbol
Element
Name
Average
Atomic
MassSlide12
Abbreviated/noble gas configuration[Ne]3s2[Ne]
= the noble
gas electron configuration
3 = main energy levels = sublevel2 = number of electrons on the sublevelSlide13
Reading the Periodic Table(Transition Elements)Elements in d-sublevel are known as transition metals.
Elements in f-sublevel,block, are called inner transition metals.
Elements on 4f row are the lanthanide series.
Elements on 5f row are the actinide series.Slide14
Reading the Periodic TableAlkali Metals -Arabic means asheShiny solids, malleable, ductile, and good conductors of electricity
Can be cut with a knife. The thin shiny surface reacts with oxygen in air & tarnishes.
Reacts with water and air
Reactivity increases going down the groupAlkaline Earth Metals - Properties similar to alkali metalsHigher density & melting pointNot as reactiveHeavier alkaline earth metals react with waterSlide15
Reading the Periodic Table Halogens- Salt formersHighly reactive due to the fact of it’
s strong attraction for electrons.
Reactviity
decreases from fluorine to iodineNoble GasesAre least reactiveArgon means “lazy one”Slide16
Periodic TrendsPeriodic table is arranged so elements with similar electron configurations and properties are in the same column. These properties of change in a predictable manners as you move across and and down the periodic table.
With this knowledge an element
’
s location on the periodic table can be used to make predictions about it’s properties.These systematic variations are known as Periodic Trends.Slide17
Periodic Trends(Atomic Radii)Atomic Radius is the center of an atom
’
s nucleus to it
’s outermost electron. Since atom have no exact boundary another method is used to determine the atomic radii.Slide18
Periodic Trends(Ionic Size)Metals tend to lose electrons to form
cations
.
Cations are smaller than the atom for same element.Nonmetals tend to gain electrons to form anions.Anions are larger than atoms for the same element.Slide19
Formation of Ions(Cations)
10 P
10 N
11 P
12 N
Neutral Ne atom
1s
2
2s
2
2p
6
10 electrons
Neutral Na atom
1s
2
2s
2
2p
6
3s
1
11 electrons
Radius =0.186 nm
11 P
12 N
Na
1+
ion
1s
2
2s
2
2p
6
10 electrons
Radius =0.095 nm
Na
1+
ion is smaller than the Na atom.
Lost it
’
s valence electronSlide20
10 P
10 N
9 P
10 N
Neutral Ne atom
1s
2
2s
2
2p
6
10 electrons
Neutral F atom
1s
2
2s
2
2p
5
11 electrons
Radius =0.064 nm
9 P
10 N
F
1-
ion
1s
2
2s
2
2p
6
10 electrons
Radius =0.136 nm
F
1-
ion is larger than the F atom.
Formation of Ions
(Anions)
Gained a valence electronSlide21
Periodic Trends(Electron Affinity)Electron Affinity is the energy given off when a neutral atom gains an electrons to produce an anion.
The more negative the electron affinity value the more likely an anion is formed.
Makes sense that as you move to the left across the period electron affinity becomes more negative.Slide22
Periodic Trends(Ionization Energy)
Ionization energy(I.E.) is the amount of energy required to remove an electron from an atom to produce a cation.
First Ionization energy is the amount of energy needed to remove the first outermost electron.Slide23
Periodic Trends(Ionization Energy)The 2nd,3rd, and 4th etc… I.E. refers to how much energy is required to remove a 2nd, 3rd, 4th, etc….electron from an atom.
The area shaded shows that removal of that particular electron will not happen because the element has an octet of electrons.
Every time an electron is removed the positive charge for the ion is increased. So at I.E.
1 for Al the ion Al1+ is formed, I.E.2 for Al the ion Al2+ is formed, and I.E.3 for Al the ion Al3+ is formed. There is no Al4+ formed because once Al loses it
’
s3 valence electrons it electron configuration is the same as Ne.Slide24
Periodic Trends(Ionization Energy)
13 P
14 N
Neutral Al
Atom
1s
2
2s
2
2p
6
3s
2
3p
1
13 electrons
13 P
14 N
Al
1+
ion formed after 1st I.E.
1s
2
2s
2
2p
6
3s
2
12 electrons
13 P
14 N
Al
2+
ion formed after 2nd I.E
1s
2
2s
2
2p
6
3s
1
11 electronsSlide25
Periodic Trend(Ionization Energy)
10 P
10 N
13 P
14 N
Al
3+
ion formed after 3rd I.E
1s
2
2s
2
2p
6
10 electrons
Neutral Ne atom
1s
2
2s
2
2p
6
10 electrons
Notice: Electron Configuration for Al
3+
ion is the same as NeSlide26
Periodic Trend(Electronegativity)
Electronegativity value increases
Electronegativity value increases
Electronegativity is the ability of an atom to attract electrons to itself in a chemical bond.
The higher the electronegativity value the more electrons in the chemical bond are attracted to the atom.
Fluorine has the highest electronegativity value of 4.0Slide27
More practiceWhich of these elements, chlorine, selenium, and bromine is (a) the smallest atom? (b) the atom with highest ionization energy?Phosphorus, sulfur, and selenium are located near each other on the periodic table. Which of these elements is (a) the largest atom? (b) the atom with the highest ionization energy?Scandium, yttrium, and lanthanum are located near each other on the periodic table. Which of these elements is (a) the largest atom? (b) the atom with the smallest ionization energy?
(a) Which of the following atoms is smallest: vanadium, chromium, or tungsten? (b) Which of these atoms has the highest ionization energy?
(a) Which of the following atoms is smallest: nitrogen, phosphorus, or arsenic? (b) Which of these atoms has the smallest ionization energy?Slide28
More practice continued6. (a) Which of the following atoms is largest: a potassium atom, a potassium ion with a charge of 1+, or a rubidium atom?Which of the following is the largest: a chlorine ion with a charge of 1-, or a bromine atom?Which of the following is the smallest: a lithium atom, a lithium ion with a charge of 1+, or a sodium atom?
Which of the following is the largest: a tellurium ion with a charge of 2-, an iodine ion with charge of 1-, or a xenon atom?
Aluminum, silicon, and phosphorus are located near each other in the periodic table. Which of these elements is (a) the largest atom? (b) the atom with the highest ionization energy?