What is the World made of? What is holding it together?

• The Greek thinker Aristotle classified the fundamental elements as fire, air, earth, and water.

• The ancient Chinese believed that the five basic components of the physical universe were earth, wood, metal, fire, and water. Pinyin, Wu Xing

• In India, 3rd century AD the five gross elements were claimed to be space, air, fire, water, and earth. Samkhya-karikas by Ishvarakrsna

Physical Science 1Chapter 17 – Properties of Atoms & the Periodic Table

The Elements: Forged in StarsThe Origin of the Elements

Chemical Symbols• Abbreviations for chemicals• Punctuation is KEY

– Capital Letters – Subscript– Superscript– Spacing

• Elements– ALWAYS Start with a capital letter– Symbols can be 1,2 or 3 letters– First letter is capitalized and 2nd &

3rd are lowercase

• CO doesn’t equal Co– CO = Carbon monoxide

– Co = Cobalt

The subatomic particles

p+ = positive charge nucleusn = no charge nucleuse- = negative charge cloud

Electrons have such a small mass compared to protons and neutrons we say electrons have no mass – but really they do.

p+ = 1 amu amu – atomic mass unit

n = 1 amu 1/12 of a Carbon -12

e- = 0 amu

QUARKSMurray Gell-Mann found the name "quark" in the book "Finnegan's Wake" by James Joyce. The line "Three quarks for Muster Mark..." Gell-Mann received the 1969 Nobel Prize for his work in classifying elementary particles.

Quark Symbol Spin Charge

Up U 1/2 +2/3

Down D 1/2 -1/3

Charm C 1/2 +2/3

Strange S 1/2 -1/3

Top T 1/2 +2/3

Bottom B 1/2 -1/3

Finding the Quark

Can you figure out which cork stands for which quark?

Fermilab – National Particle Accelerator Lab Chicago IL

EXTRA CREDIT: Find out what a neutrino is & why it’s important to SD

Quarks: Inside the Atom

Models of the Atom over timeThe Players Democritus – indivisible atom 450 BC

John Dalton – atom 1803

John Thomson – Plum Pudding model 1897 Nobel Prize 1906 Discovered the electron 1897 – cathode ray tube

Ernest Rutherford – Rutherford model 1911 Gold Foil experiment – positive nucleus (protons)

Chadwick – discovered the neutron 1932

Niels Bohr – Bohr model 1913 Nobel Prize 1922

Erwin Schrödinger & Werner Heisenburg - Charged Cloud model 1920’s

Poster Project• You must create a poster 8x11 describing how the atom

has changed over time – 6 atomic models with sketches – Describe the structure of each model & how it has been modified

or enhanced from the previous model– Include Dates & Names associated with the models– Explain any technology associated with the model. What

experiments did they use to establish the model– Include when the proton electron and neutron were found

– You must have at least 2 sources – half credit will be given to any posters without sources

– Color & Organization are important– These will be displayed – Have FUN!!!

Atomic number

Always the smaller of the 2 #

Always a whole # (no decimals)

= number p+

Atomic mass

Always the BIGGER of the 2 #

Usually a decimal

= # p+ & n

Atoms: by the NUMBERS

• Protons = Atomic Number– Atoms get their identity and properties due to the

number of protons they have – change the #p+ change the element

• Electrons = Number of protons– For neutral atoms ions are different

• Neutrons = Atomic Mass – Atomic Number– Atoms of the same element can have different

masses. These are called isotopes. The difference in mass is due to more or less neutrons

• practice problems

Ions• atom or molecule with missing or extra

electrons– Ions are charged particles (positive or negative)

• charge = #protons - #electrons • charge given as a trailing superscript • positive ions are cations X+

• negative ions are anions X–

Symbols

x Charge

Atomic Number

“Z”

Atomic Mass

Number of atoms

Isotopes• Atoms of the same element can have different masses

– The difference in mass is due to more or less neutrons• Isotopes are different flavors of each element• Atoms with a too few or too many neutrons can exist for a while, but

they're unstable or radioactive• The atomic mass is recorded as a decimal because it illustrates an

average of the isotopes abundance • Radiometric Dating - Aging the Earth

Development of the Periodic TableIn 1829

Dobereiner proposed the Law of Triads: The middle element in the triad (group of 3 elements) had atomic weight that was the average of the other two members

     Ca   Sr   Ba     (40 + 137) ÷ 2 = 88       40     88     137

Li   Na  K         Cl   Br   I 7     23     39           35    80   127

Law of Octaves

John Newlands proposed The Law of Octaves: When elements are arranged in increasing atomic mass the 1st & 8th elements exhibit similar behavior. This behavior repeats in a periodic fashion

In 1863

Little attention was paid to Newlands work because he linked his finding to music.

Dimitri Ivanovich Mendeleev

“I began to look about and write down the elements with their atomic weights and typical properties, analogous elements and like atomic weights on separate cards, and this soon convinced me that the properties of elements are in periodic dependence upon their atomic weights.” --Mendeleev, Principles of Chemistry, 1905, Vol. II

Mendeleev's periodic table was arranged with increasing atomic weight and attention to chemical properties.

Periodic Table contained columns (groups) & rows (periods).

Mendeleev left gaps in the table. He predicted the discovery of new elements that would fill these gaps. 

eka-aluminum, eka-boron, and eka-siliconGallium, Scandium and Germanium

In 1906, Mendeleev came within one vote of receiving the Nobel Prize in chemistry

In 1869 & 1871

Moseley's Periodic Law • It starts with Rutherford's landmark Gold Foil

Experiment discovering the proton in 1911

• Henry Moseley was able to derive the relationship between x-ray frequency and number of protons.

• Moseley Periodic Law arranges the elements according to increasing atomic numbers and not atomic masses,

– some of the inconsistencies associated with Mendeleev's table were eliminated.

• The modern periodic table is based on Moseley's Periodic Law (atomic numbers).

• At age 28, Moseley was killed in action during World War I

In 1914

The last major change• Glenn Seaborg discovered the Inner transition metals

transuranium elements 94 to 102 • This reconfigured the periodic table by placing the

lanthanide/actinide series at the bottom of the table. • In 1951 Seaborg was awarded the Nobel Prize in chemistry and

element 106 was later named Seaborgium (Sg) in his honor.

In 1940

Groups by NUMB3RSIUPAC 1 2 13 14 15 16 17 18

American 1A 2A 3A 4A 5A 6A 7A 8A

European IA IIA IIIB IVB VB VIB VIIB VIIIB

3 4 5 6 7 8 9 10 11 12

3B 4B 5B 6B 7B ----8B----- 1B 2B

IIIA IVA VA VIA VIIA -------VIIIA------ IB IIB

Group or Family – Vertical columns on the PT

Elements in a groups have similar properties

Period – Horizontal rows on the PT

Metals• First metal used was gold

– 6000 years ago• Followed by Cu Ag Sn Fe • Al was not refined until

1800’s• Hg mercury is the only

metal that is a liquid at room temp

Metals• Most elements are metals. • 88 elements found to the

LEFT of the Zigzag Line• Physical Properties of Metals:

– Luster (shininess) – Good conductors of heat and electricity – High density (heavy for their size) – High melting point – Ductile (drawn out into thin wires) – Malleable (hammered into thin sheets)

• Chemical Properties of Metals:– Easily lose electrons (positive ions CATIONS)– Corrode easily

ALKALI METALS – GROUP 1, 1A & IA

• Lithium Li Sodium Na Potassium K

• Rubidium Rb Cesium Cs Francium Fr

Extremely Rare

Radioactive

ALKALI METALS – GROUP 1, 1A & IA

• Soft metals – they can be cut with a knife

• Most reactive of all the metals - React rapidly with oxygen and water

• Do not occur in nature in their elemental form

• Stored under oil • Will form a +1 ion by

giving away their one valence electron

Alkaline Earth Metals Group 2 2A & IIA• Beryllium Be Magnesium Mg Calcium Ca

• Strontium Sr Barium Ba

Radium Ra

              

           

     

          

              

           

     

          

Alkaline Earth Metals Group 2 2A & IIA

• Do not occur in nature in their elemental form

• Will form a +2 ion by giving away their two valence electrons

• Uses– Fireworks– Ca – Bones & Teeth– Ba - X-Rays

              

          

Transition Elements Group 3-12

• These elements are most familiar to the public because they are found in nature in their elemental form

• Often form colored compounds – Chromium precious gems (emeralds and rubies)– Cadmium yellow – Cobalt blue

• Iron Cobalt and Nickel Group 8 9 & 10– Iron Triad– Steel– Fe

• most widely used metal• 2nd most abundant in the earth’s crust

• Copper Silver and Gold Group 11– Coinage metals– Cu - wiring– Ag – photographs

• Zinc Cadmium and Mercury Group 12– Coat or Plate metals – Batteries– Thermometers

INNER Transition Metals• Lanthanides

– Elements 58 – 71– Elements used in motion

pictures industry – Produce colors you see on

the TV• Actinides

– Elements 90 – 103– All actinides are radioactive

and unstable– Thorium and Uranium are

found in the earth’s crust– Uranium – nuclear reactors

NONMETALS• Found to the RIGHT of the zigzag line

– Hydrogen is considered a nonmetal• Group 18 – Noble Gasses are the only

group that consists of all nonmetals• Group 17 - Halogens• Properties

– Nonmetals gain electrons to become stable – anions

– Most are gasses at room temp– Not malleable– Not ductile– Poor conductors of heat and electricity– No Luster – Dull

• Important nonmetals in Humans– Carbon Hydrogen Nitrogen & Oxygen

Energy Levels & Electrons• Electrons are always moving around the nucleus

and so possess potential and kinetic energy.

• Electrons can only possess certain values of energy, or specific energy levels. (Bohr Model)

Bohr deduced that:• electrons inside an atom possess different

energies – e- in the 1st orbit belong to the 1st energy level – e- in the 2nd orbit belong to the 2nd energy level – e- in the 3rd orbit belong to the 3rd energy level

• each energy level of an atom could only accommodate a certain number of electrons.

– first energy level = 2 electrons – second energy level = 8 electrons – third energy level = 18 electrons

Representative Elements in: Number of Valence ElectronsGroup IA all elements have 1 valence electronGroup IIA all elements have 2 valence electronsGroup IIIA all elements have 3 valence electronsGroup IVA all elements have 4 valence electronsGroup VA all elements have 5 valence electronsGroup VIA all elements have 6 valence electronsGroup VIIA all elements have 7 valence electronsGroup VIIIA all elements have 8 valence electrons

The Lewis electron-dot diagrams focus on the electrons in the highest energy level in the atom, the valence electrons.

Valence electrons are the electrons that participate in chemical reactions.

Lewis Dot Diagrams

Lewis Dot Diagrams of Selected Elements

• Lewis Dot uses the symbol of the element and dots to illustrate the number of electrons in the outermost energy level

• Dots are placed in 8 positions around the symbol– 2 spots for each Right Left Top & Bottom– e- are not paired until they are at least 5 valence e-

• Elements of the same group (column) have the same number of valence electrons