the periodic table
DESCRIPTION
The Periodic Table. Unit 3. Origins. In 1817, Johann Dobereiner found that the properties of the metals calcium, barium and strontium were very similar. He grouped these elements in a triad. Origins (Cont.). - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/1.jpg)
The Periodic Table
Unit 3
![Page 2: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/2.jpg)
Origins In 1817, Johann
Dobereiner found that the properties of the metals calcium, barium and strontium were very similar. He grouped these elements in a triad.
![Page 3: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/3.jpg)
Origins (Cont.)
In 1863, John Newlands arranged the elements in order of their increasing atomic masses. He noted that there appeared to be a repetition of similar properties every eighth element.
The Law of Octaves shows the same properties repeated every eight elements.
![Page 4: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/4.jpg)
Dimitri Mendeleev In 1860’s, Dimitri Mendeleev
studied elements and also believed that the properties of the elements were a function of their atomic masses.
However, he believed that similar properties occurred after periods (horizontal rows) that could vary in length.
![Page 5: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/5.jpg)
Mendeleev (Cont.) In 1869 he published his first
periodic table, leaving some blank spots in order to group all the elements with similar properties in the same column.
He explained the blank spots were for elements not yet discovered, but in 1871 he predicted their atomic mass and properties.
![Page 6: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/6.jpg)
The Periodic Law His predictions were very nearly
correct. Mendeleev stated that the properties of the elements are a periodic function of their atomic masses. This is called the periodic law.
For his work, he is known as the Father of the Periodic Table.
![Page 7: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/7.jpg)
The Modern Periodic Law There was a problem with this
arrangement. Henry Moseley found the reason for these exceptions to Mendeleev’s periodic law.
Moseley’s X-ray experiments showed that elements were positioned better if done by their atomic number.
The modern statement of the periodic law is the properties of the elements are a periodic function of their atomic numbers.
![Page 8: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/8.jpg)
The Modern Periodic Table A horizontal row is referred to as
a period. A vertical column is referred to
as a group or family. There are 18 groups in the
periodic table.
![Page 9: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/9.jpg)
Stability of Atoms One of the primary rules in
chemistry is that atoms with a full outer level are particularly stable (less reactive).
For all such elements, except hydrogen & helium, the outer level contains 8 electrons, these outer electrons are called an octet.
The fact that eight electrons in the outer level render an atom unreactive is called the octet rule.
![Page 10: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/10.jpg)
![Page 11: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/11.jpg)
Characteristics of Metals: Hard and shiny Conduct heat and
electricity Malleable &
ductile They are to the
left of the stair step.
Have only a few electrons in their outer level Gold &
Copper
o They tend to lose electrons to become positive ions.
![Page 12: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/12.jpg)
Characteristics of Non-metals: Gases or brittle solids
at room temperature Dull and they are
insulators Are to the right of the
stair step Have more electrons
in their outer level Can share their
electrons or gain electrons to become negative ions.
Carbon & Sulfur
![Page 13: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/13.jpg)
Metalloids They are elements right
along the stair steps on the chart. (Except Al)
Metalloids share characteristics of both metals and non-metals.
For example, Silicon is shiny like a metal, but is brittle and is not a good conductor of electricity.
![Page 14: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/14.jpg)
Column IA: Alkali Metals Alkali metals have a
silvery appearance and are soft enough to be cut with a knife.
They are extremely reactive with moisture and are never found as free elements in nature.
Potassium in water
![Page 15: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/15.jpg)
Column IIA: Alkaline Earth Metals Alkaline earth metals are harder,
denser and stronger than alkali metals.
They are less reactive but are never found as free elements in nature.
Pure Calcium is too reactive to be free in nature but can be found in Marble, Calcium Carbonate (CaCO3).
![Page 16: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/16.jpg)
Transition Metals They occupy columns IIIB – IIB. They are typically less reactive
than alkali or alkaline earth metals.
Some are so unreactive they do not easily form compounds and exist in nature as free elements.
Palladium, Platinum and Gold are transition metals.
![Page 17: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/17.jpg)
Column VIIA: Halogens The halogens are the most reactive
nonmetals. They react vigorously with most metals to
form “salts”. Fluorine and chlorine are gases at room
temperature.
Bromine is a reddish liquid.
Iodine is a dark purple solid.
![Page 18: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/18.jpg)
Physical Properties of Halogens
Demo04-2.mov
![Page 19: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/19.jpg)
Column VIIIA: Noble Gases First discovered in 1894 when
Argon was discovered. Noble gases were undetected
due to their total lack of chemical reactivity.
They have full valence shells, 8 valence electrons, with the exception of Helium which has 2.
![Page 20: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/20.jpg)
The Lanthanides and Actinides Lanthanides contain elements from
#58, Cerium, to 71, Lutetium in the top pullout row.
Actinides contain elements from #90, Thorium, to 103, Lawrencium in the bottom pullout row.
Both series are off of group IIIB and are in periods 6 & 7 respectively and are metals.
![Page 21: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/21.jpg)
Practice
WS #1 – Blank Ptable WS #1 Make your Own Periodic Tabl
e
![Page 22: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/22.jpg)
Periodicity Periodicity of properties can be
observed in any group on the periodic table.
The reason for periodicity is explained in the arrangement of electrons around the nucleus.
![Page 23: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/23.jpg)
Periodicity There are trends in these
properties as you go down in a group or across in a period.
NOTE: When discussing trends in properties, the Noble gases are never included.
![Page 24: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/24.jpg)
Atomic Radius It measures the size of the atom Decreases as you go across a
period (left to right). Increases as you go down a
group because you add another level of electrons.
![Page 25: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/25.jpg)
![Page 26: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/26.jpg)
Ionic Radius
![Page 27: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/27.jpg)
First Ionization Energy The energy needed to remove
the most loosely held electron from an atom.
It increases as you go across a period (left to right).
It decreases down a group.
![Page 28: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/28.jpg)
![Page 29: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/29.jpg)
Electron Affinity Electron Affinity is the attraction
of an atom for an electron. The electron affinity increases
as you go across a period (left to right) and decreases as you go down a group.
In general, as electron affinity increases, an increase in ionization energy can be expected.
![Page 30: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/30.jpg)
![Page 31: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/31.jpg)
Electronegativity The relative tendency of an atom
to attract electrons to itself when it is bonded to another atom.
Electronegativities of elements have the same trend as ionization energy and electron affinity.
![Page 32: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/32.jpg)
![Page 33: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/33.jpg)
Conceptual Short Cut!
As the atomic radius gets smaller, the: valence electrons are closer to the
nucleus, nucleus pulls harder on the electrons, Ionization energy, electron affinity, and
electronegativity will increase.
![Page 34: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/34.jpg)
Periodic Trends SummaryAll arrows show increases!!
![Page 35: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/35.jpg)
Zeff : Solution for Difficult Problems
Effective Nuclear Charge: Zeff
Zeff = Z – S Where:
Z = atomic number S = # of shielded (non-valence) electrons
The higher the Zeff, the greater pull of the positive nucleus on the valence electrons, which means a smaller atomic radius
![Page 36: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/36.jpg)
Zeff Continued
Example: Mg vs. Mg2+
Zeff for Mg = 12 -10 n= +2 Zeff for Mg2+ = 12 – 2 = +10 Therefore: the effective positive charge
on Mg2+ is WAY bigger, which means the nucleus pulls on the outer electrons WAY harder, and the atom is subsequently WAY smaller.
Higher Zeff = smaller atomic radius
![Page 37: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/37.jpg)
Electronegativity Cont. The most reactive metals (lower left)
have the lowest electronegativities. Fluorine, a nonmetal, is the most
electronegative element with a value of 4.0.
The difference in values for two elements tells you how the elements are bonded together when they combine with each other.
![Page 38: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/38.jpg)
Electronegativity Cont. If the difference in electronegativity
values between 2 elements is below 1.7, it indicates a covalent bond.
If it is greater than 1.7, an ionic bond is indicated.
![Page 39: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/39.jpg)
Reactivity Trend
Some metals and nonmetals are more reactive then others.
The easier it is for a metal to lose electrons, and the easier it is for a nonmetal to gain electrons, the more reactive they are.
![Page 40: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/40.jpg)
Reactivity of Metals Lose electrons and become
positive ions. The farther the valence
electrons are from the nucleus, the less the protons pull and the easier (takes less energy) it is to remove an electron .
Reactivity increases down a group and decreases across a period.
What is the most reactive metal?
![Page 41: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/41.jpg)
Reactivity of Non-Metals Gain electrons and become negative
ions. The closer the valence electrons are
to the nucleus, the more the protons pull and the easier it is to pull in an electron.
Reactivity decreases down a group and increases across a period.
What is the most reactive non-metal?
![Page 42: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/42.jpg)
Metal/Nonmetal Reactivity
Most reactive metals – bottom, left
Most reactive nonmetals – top, right
![Page 43: The Periodic Table](https://reader035.vdocuments.site/reader035/viewer/2022062309/56814577550346895db2491d/html5/thumbnails/43.jpg)
Practice
WS #2 Periodic Trends WS #2 Periodic Trends