The Periodic Properties of the Elements

By Lauren Querido, Chris Via, Maggie Dang, Jae Lee

The Founders of the Periodic Table

Luthar Meyer

http://chemheritage.org/classroom/chemach/images/lgfotos/04periodic/meyer-mendeleev2.jpg

Dmitri Mendeleev

http://nuclphys.sinp.msu.ru/persons/images/mendeleev.gif

7.1 Developing the Periodic Table

Dmitri Mendeleev (1869)- and Luthar Meyer Published very similar documents to classify the elements. And were the first to make the modern periodic table Used chemical and physical properties to

classify Henry Moseley (1887-1915)- Developed

concept of atomic numbers Found that frequency increases as the

atomic mass increases

7.2 Electron Shells and Size of Atoms

Electron Shells in Atoms Gilbert N. Lewis – electrons are arranged

in shells surrounding the nucleus. Atomic sizes-http://grandinetti.org/Teaching/Chem121/Lectures/PeriodicTrends/assets/radiitable.gif

Bonding Atomic Radius- the distance between the center of two bonding atoms

http://www.chembook.co.uk/fig13-1.jpg

Practice Problem #1

Predict the lengths of C-S, C-H, and S-H bonds in this molecule

Radius of C = 0.77 Å Radius of S = 1.02 Å Radius of H = 0.37 Å

When determining the bonding radius, you add the radius of the bonding atoms together

Answer to Practice Problem #1

C-S bond length = radius of C + radius of

= 0.77 Å + 1.02 Å = 1.79 Å C-H bond length = 0.77 Å + 0.37 Å = 1.14 Å S-H bond length = 1.02 Å +0.37 Å = 1.39 Å

7.2 continued

When moving across a row, the number of core electrons stay the same but the nuclear charge increases

The effective nuclear charge increases even though the quantum number remains the same

Shielding is the process of blocking the protons effective charge on the outermost electrons

7.3 Ionization Energy

Ionization Energy – to remove an electron from the ground state

Second Ionization – removing the 2nd electron from the ground state

I1<I2<I3 and so forth; It increases in magnitude

The greater effective nuclear charge, the greater the ionization energy

7.3 cont..

There is a sharp increase in ionization energy when an inner shell electron is removed

Periodic Trends1. Within each row, the ionization energy

increases with atomic number2. Within a group, the ionization energy

generally decreases with increasing atomic number

7.3 cont..

3. The ionization energy of transition elements & f-block metals increase slowly as you read from left to right.

The transition in ionization energy are affected by how strong an electron is attracted to an atom

It is affected by the effective nuclear charge and the average distance from the nucleus.

7.3

The irregularities are explained through the periodic table

Electrons in the s orbital are more effective at shielding than in the p orbital

7.4 Electron Affinities

Positive ionization energy = energy put into atom in order to remove electrons

Electron affinity = attraction of change in energy when the electron is added

Most atoms = energy is released when electron is added

A positive electron affinity, an ion will not form

7.4 cont..

On the periodic table, electron affinity becomes negative towards halogen (closest to being stable)

The electron affinity does not change when they move down a group (noble gases)

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Element Classificationhttp://www.elementsdatabase.com/Images/periodic_table1.gif

7.5 Metals, Nonmetals, and Metalloids

Metals Tend to have low ionization energies and

lose electrons when they undergo chemical reaction

Most metal oxides are basic oxides that dissolve in water react to for metal hydroxides

Metal Oxide + Water Metal Hydroxide Metal oxides show their basicity by

reacting with acids to form water and saltsMetal Oxide + Acid Salt + Water

7.5

Characteristics of Metals Have a shiny luster Various colors Solids are malleable and ductile Good conductors of heat and electricity Most metal oxides are ionic solids that are

basic

7.5

Nonmetals Tend to gain electrons and become anions

Metal + Nonmetal Salt Most nonmetal oxides are acidic oxides

that dissolve in water react to form acidsNonmetal Oxide + Water Acid

The acidity of nonmetal oxides is shown by the fact they dissolve in basic solutions to form salts

Nonmetal Oxide+ Base Salt + Water

7.5

Characteristics of Nonmetals Do not have a luster Various colors Solids are usually brittle; some are hard,

and some are soft Poor conductors of heat and electricity Most nonmetallic oxides are molecular

substances that form acidic solutions

7.5

Metalloids Have properties intermediate between

nonmetals and metals

http://www.rkm.com.au/METALLOIDS/metalloid-images/METALLOID-SILICON-500.jpg

7.6 Group Trends for the Active Metals

Group 1A: The Alkali Metals (most active) Metallic Characteristics

Silvery Metallic luster & high thermal Electrical conductivities Have low densities & melting points Very reactive b/c they want to lose 1 electron

to form ions with a 1+ charge so it becomes more stable

7.6 cont..

As you move down a group Atomic radius increases 1st ionization energy decreases

7.6 cont..

Group 2A: The Alkaline Earth Metals Properties of Alkaline Earth Metals

Harder More Dense Melt at higher temps Highly Reactive

Compared to alkali Metals, Alkaline Earth metals..

Have lower 1st ionization energies Are less reactive

7.7 Group 6A Oxygen is a colorless gas at room

temperature while all the other elements in this group are solid.

Oxygen has two main forms: 02=“oxygen” and 03=“ozone”.

This is an example of an allotrope, it has different forms of the same element.

7.7

The most stable form of sulfur is S8, It is a yellow solid.

All of the elements in this group have the tendency to gain electrons form other elements.

http://www.science.uwaterloo.ca/~cchieh/cact/fig/s8.gif

7.7

Group 7A: Halogens Halogens is named Greek words, “halos” and

“gennao” meaning salt formers. Fluorine and Chlorine are gases, bromine is a

liquid, and iodine is a solid at room temperature.

These elements melting and boiling points increase with atomic number.

These elements have highly negative electron affinities because they have the need to gain electrons from other elements.

The Fluorine atom is very reactive!

http://www.chemistryland.com/ElementarySchool/BuildingBlocks/FluorineAttracts.jpg

7.7

Group 8A: Noble Gases All of the elements are nonmetals at

room temperature and they are monatomic

They are very unreactive because they have completely filled s and p orbitals.

They also have very large 1st ionization energies.

That’s All Folks