Periodic Properties of Elements Tadas Rimkus Krishna Trehan Rachel Won Soo Jeon.
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Transcript of Periodic Properties of Elements Tadas Rimkus Krishna Trehan Rachel Won Soo Jeon.
Periodic Propertiesof Elements
Tadas RimkusKrishna Trehan Rachel WonSoo Jeon
What is the SWBAT????
Objective Know a brief history of the periodic table Know the effective nuclear charge Examine periodic tends in the atomic size, ionization
energy, and electron affinity Examine the sizes of ions and their electron
configurations Explore some of the difference in the physical and
chemical properties of metals, nonmetals, and metalloids.
Discuss some periodic trends.
I <3 The Periodic Table
Mendeleev, Meyer, Moseley strived to investigate the possibilities of classifying elements in useful ways.
Mendeleev and Meyer - developed the periodic table on the basis of the similarity in chemical and physical properties. He predicted Ga, Ge, and Sc.
Moseley- established that each element has a unique atom number. - found out that each element produces X rays of a
unique frequency; the frequency increases as the atomic mass increases
Rutherford- proposed the nuclear model of the atom. Element in the same column of the periodic table have the same
number of electrons
Sizes of Atoms and Ions
Ionic size - the size of an ion plays an important role in determining the structure and stability of ionic solids!
Periodic Trend - Metals tend to lose electrons. The size of the atom becomes smaller with the loss of each!
Continue…
Consecutive electron. The nuclear charge can have a greater pull on the electrons with the loss of each electron.
Iso-electronic ions - ions containing the same number of electrons, thus having the same electron configuration!
Continue… AGAIN!
Periodic Trend - Nonmetals tend to gain electrons. The size of the atom becomes larger with the addition of each consecutive electron. The nuclear charge has less of a pull on the electrons with the gain of each electron due to greater electron repulsion!
7.5 Electron Affinities
Ionization Energy: energy required to remove an valence electron
Cl(g) Cl+(g) + e- ΔE = 1251 kJ/mol See how E is positive? This is the energy which you must add, in
order to remove an electron from Chlorine
Electron Affinity
Did you know that atoms can gain electrons to gain a negative charge?!
This energy change that occurs is called ELECTRON AFFINITY because it measures the ATTRACTION between the newly added electron and the atom
It shows how much the atom WANTS the electron!
Electron Affinity
So……. FLUORINE wants an electron MORE than LITHIIUM, meaning it would have a LARGER electron affinity!
http://www.chemguide.co.uk/inorganic/group7/eadiag.gif
Ionization Energy
the amount of energy need to remove an electron from a specific atom or ion in its ground state
1st Ionization Energy energy needed to remove the 1st electron
from an atom
Ionization Energy… CONTINUE
ACROSS- increase As you go across the periodic table, the
electrons are closer to the nucleus increasing the energy necessary to remove an electron
DOWN- decrease As you go down the periodic table, the electrons
are farther from the nucleus
Continue!
Nuclear Charge the change in the nucleus or the number of protons ACROSS- increase DOWN- increase Atomic Radius one half the distance from center to center of like atom down-
increases As you go down the periodic table, a new energy level is added
increasing the size of the atoms Ex) of the following, which has the highest and lowest first ionization
energy? Answer: Highest- C Lowest- AL
Periodic Trends Of Electron Affinity
Electron Affinity tends to decrease as we go from left to right!
BUT WHY?!?!?!?!?!?!?!?!?!?!?! This is because the elements on LEFT
side of the Periodic Table of LESS valence electrons.
Electron Affinity
the energy change when an electron is added to a neutral atom to from a negative ion
ACROSS- increase DOWN- decrease
Continue?
The elements on the right, are one electron away from GETTING A FULL OCTET!
They will have a high affinity, so they can gain the last electron.
(The more negative the electron affinity, the greater the attraction for an electron)
METALS!!! Woohooo
Metals are the shiny things we have learned to love and treasure
They are ductile, conduct heat and electricity, and malleable.
They are all solid (except Mercury!) at room temperature.
They can have high melting points, for example Chromium has a melting point at 1900 C.
Metals, CONTINUED!
Metals have low ionization energies (energy required to remove an valence electron)
WHICH MEANS, they tend to form positive ions EASILY!!!!!!!
Because of this… when metals go through CHEMICAL REACTIONS they are OXIDIZED
But what does oxidized mean?!?!
An metal has been OXIDIZED when it loses electrons.
Metals are oxidized by many different substances INCLUDING OXYGEN GAS (O2) and ACIDS!
Alkali and Alkaline Earth Metals
The charge of ALL alkali metals is ALWAYS 1+ The charge of ALL alkaline earth metals is
always 2+
Transition Metals!
Many transition metals have a +2 charge, BUT +2 AND +3 is also encountered!
A characteristic of the Transition elements is to be able to form ions!
NONMETALS!
Nonmetals are overall worse than metals
They are not lustrous and are generally poor conductors of heat and electricity.
They have a lower melting point than those of metals, BUTT the diamond form of carbon melts at 3570 C
Nonmetals, CONTINUED!
UNDER ORDINARY CONDITION:Seven elements of the nonmetals exist in
diatomic elements ****BrNClHOF****Because of their ELECTRON AFFINITY,
nonmetals tend to GAIN ELECTRONS when they react with metals.
Compounds composed entirely of nonmetals are molecular substancesEx: Oxides, Halides, and Hydrides
METALLOIDS
Properties of Metalloids include propertis from both Metals and NonmetalsEx: Silicon is shiny like a metal, but is brittle
like a nonmetal
Group Trends of Active Metals!
Group 1A Alkali MetalsSoft, metallic solidsShiny, and have a high thermal electrical
conductivity.Low density, and low melting points.As you move down the group, the atomic
radius increases, and ionization energy decreases
Alakali metals are extremely reactive toward WATER and OXYGEN
Alkali Metal Ions are colorless and produce a characteristic a color when combusted
EX: Burning sodium produces a yellow flame.
Group 2A: Alkaline Earth Metals
Ionization energies of these metals are low, but not as low as the alkali metals
They are less reactive then the 1A Metals The “heavier” alkaline earth metals are
more reactive than the lighter ones
Group Trends for Non Metals
Hydrogen:Even though Hydrogen is in the Alkali metals,
it does not belong to any specific groupHowever, Hydrogen can have metallic
properties under extreme pressure Ex: the center of Saturn is surrounded by a thick
shell of pressurized Hydrogen
Group 6A: The Oxygen Group
In the 6A group, there is a change from non-metallic to metallic character
Oxygen through Selenium are non-metals and Tellurium has some metallic properties
Group 7A: Halogens
The Halogens are tpically nonmetals Their melting and boiling points increase
as they go down the coloumn. Halogens, have ridiculously high electron
afifnities, this is because they really want to get ONE MORE ELECTRON, to mimic the Noble Gasses.
Noble Gasses
All gasses at room temperature. Because of their stable and filled outer
orbitals, they are extremely un-reactive