True Science!

Do you see a pattern?

The Periodic Table History Dmitri Mendeleev (1834-1907) Mendeleev struggled to find some order in the 63 elements that were known at that time. Working with cards that he made showing the properties of the elements he realized that there were properties that repeated as the atomic mass increased. The properties seem to repeat every 8th element. He formed a table that showed this observation:

Mendeleev noted patterns in the combining ratios of elements The Elements Lithium (Li), Sodium (na), and Potassium (K) all bound with oxygen in the ratio of two atoms per oxygen atom: R2O The Elements Beryllium (Be), Magnesium (Mg), and Calcium (Ca) all bound with oxygen in the ratio of one atom per oxygen atom: RO Boron (B) and Aluminum (Al) form R2O3 Carbon (C) and Silicon (Si) formed RO2 Oxygen Oxygen Oxygen Oxygen Oxygen Oxygen

This is Mendeleev's rough draft of the first periodic table

When arranged in order of their atomic mass the elements repeat their properties every 8th element

low C middle C high C

observation of repeating properties He called the observation of repeating properties The "Periodic Law" These elements showed repeating properties

From the gaps present in his table, Mendeleev predicted the existence unknown elements which he called eka-silicon eka-boron eka-aluminum The elements gallium scandium germanium were found later to fit his predictions quite well.

Electron Configuration Trends in the Periodic Table Electron Configuration In the Periodic Table

Why did the elements repeat properties every 8th element?

Order of Energy (filling) 1 2 3 5 4 6 7 8 10 11 9 12 14 15 16 13 17 Order of Energy (filling)

p-orbitals 2 3 4 5 6 7 8 These elements have one or two There are 8 columns in the periodic table that repeat the same number of valence electrons p-orbitals 2 1 3 4 5 6 7 8 s-orbitals These elements have one or two valence electrons

according to ATOMIC NUMBER The table is arranged according to ATOMIC NUMBER From #1 to #116

The Periodic Table is composed of Groups…..(18 of these)

And Periods…..(7 of these)

Classifying the Elements Trends in the Periodic Table Classifying the Elements

Alkali Metals Special Chemical Families Link to website showing special families of elements

Alkaline Earth Metals Special Chemical Families Link to website showing special families of elements

Halogens Special Chemical Families Link to website showing special families of elements

Noble Gases Special Chemical Families Link to website showing special families of elements

Oxygen family Special Chemical Families Link to website showing special families of elements

Nitrogen family Special Chemical Families Link to website showing special families of elements

Trends in the Periodic Table Trend #1 Metallic Properties

Metallic Properties More metallic Movie Clip on Metalic trends in table Metallic Properties More metallic

Metallic Properties Less metallic

Metallic Properties Very NON-metallic Very metallic Click on the Table to bring up the website Metallic Properties Very NON-metallic Very metallic

Trends in the Periodic Table Trend #2 Atomic Size

Atomic Size (radius) smaller bigger “Neutral” atom with the same number of protons as electrons smaller bigger http://cwx.prenhall.com/petrucci/medialib/media_portfolio/text_images/046_AtomicRadii.MOV

Why do the elements get smaller as you go right even though they are actually getting heavier? Answer: As they get heavier they have more protons which pull the oppositely charged electrons IN tighter and tighter.

They get bigger as you go down because you are adding more layers of electrons.

Trends in the Periodic Table Trend #3 Ionization Energy

electron Ionization Energy The Energy required to LOSE electrons

Metals tend to LOSE electrons

Non-metals tend to GAIN electrons

LOST or GAINED an lectron Ion.... An Atom that has LOST or GAINED an lectron or electrons 3s1 2s22p6 1s2 The illustration shows Sodium losing an electron and becoming positively charged. It loses the 3s1 electron. Sodium ions always have a +1 charge +1

11 protons 11 electrons 17 protons 17 electrons 17 protons 18 electrons 11 protons 10 electrons

Ions of Sodium and Chlorine

Some elements lose or gain two or more electrons Oxygen gains 2 electrons Magnesium loses 2 electrons

Ionization Energy The energy needed to pull an electron off of an atom 2s22p6 3s1 1s2 +1

Sizes of ATOMS and their IONS The purple atoms are the NEUTRAL atoms The Red atoms are the POSITIVE ions The Blue atoms are the NEGATIVE ions

Trends in the Periodic Table Trend #4 Electronegativity

Electronegativity The ability of an atom to ATTRACT electrons

Electronegativity How hard does an atom pull an electron toward itself? Electronegativity ( also called ELECTRON AFFINITY)

SUMMARY of some of the trends in the periodic table http://wps.prenhall.com/wps/media/objects/476/488316/ch09.html