Periodic Table Mr. Bridgers 8 th Grade Science

I will be able to 0. Compare researchers that contibuted to the formation of the periodic table 1. Name the rows on a periodic table. 2. Name each column on a periodic table. 3. Name the two divisions of the periodic table? 4. Synthesize the information that the element key provides.

Dmitri Mendeleev ( ) Russian Chemist Published the first version of the period table in 1869 Arranged elements according to increasing atomic mass His periodic table had gaps

Discovering the Elements By the year 1869, sixty three elements had been discovered. A Russian scientist named Dmitri Mendeleev discovered that the elements followed certain patterns.

Mendeleev’s Role Mendeleev noticed that some elements shared physical and chemical properties. –Example: fluorine and chlorine are both gases that irritate your lungs. –Example: copper and silver are both metals that tarnish when exposed to air.

Patterns Mendeleev tried to find patterns in the elements using –Melting point –Density –Color –Atomic mass –Chemical bonds

Patterns He noticed that if he put the elements in order of increasing atomic mass, patterns appeared. He also noticed that the properties of the elements repeated. He put these elements in order by atomic mass, but also grouped them according to properties.

Henry Moseley ( ) Made improvements to Mendeleev’s Periodic Table Arranged elements by atomic number instead of mass Realized that there were undiscovered elements

Henry Moseley In 1913, through his work with X-rays, he determined the actual nuclear charge (atomic number) of the elements*. He rearranged the elements in order of increasing atomic number. *“There is in the atom a fundamental quantity which increases by regular steps as we pass from each element to the next. This quantity can only be the charge on the central positive nucleus.”

Henry Moseley His research was halted when the British government sent him to serve as a foot soldier in WWI. He was killed in the fighting in Gallipoli by a sniper’s bullet, at the age of 28. Because of this loss, the British government later restricted its scientists to noncombatant duties during WWII.

The Modern Periodic Table

The Element Key The Element Key provides lots of important information

Time for Vocabulary Period: A row of elements on a periodic table. Remember rows fly across. Group: a column of elements on a periodic table that share similar characteristic. Remember groups fall down.

A Group. What do they share?? As we know now, groups are a column of elements that share characteristics. The characteristic is that they have the same # of electrons in the outer shell. Look at your table…Tell me if you notice something!

More Vocabulary Metal: an element that has luster and is a good conductor of heat and electricity. Nonmetal: elements that are usually gases or brittle solids at room temperature and are poor conductors of heat and electricity. Metalloid: an element that shares some properties with metals and some with nonmetals.

Representative Elements Groups 1-2 & Alkali Metals Alkaline Earth Metals The Boron Family The Carbon Group The Nitrogen Group The Oxygen Group The Halogens The Noble Gases

Alkali Metals are… Any of the elements lithium, sodium, potassium, rubidium, cesium, and francium, occupying Group IA (1) of the periodic table. They are very reactive, electropositive, monovalent metals forming strongly alkaline hydroxides

The Alkali Metals Group 1 Elements: -Lithium -Rubidium -Sodium -Cesium -Potassium -Francium Silvery Solids Low Densities Low Melting Points

The Alkaline Earth Metals The Group 2 Elements -Beryllium -Magnesium -Calcium -Strontium -Barium -Radium Denser than Alkali Metals Higher melting points than Alkali Metals

The Boron Family Group 13 Elements -Boron -Aluminum -Gallium -Indium -Thallium All are metals except Boron Aluminum is the most common metal in the Earth’s crust.

The Carbon Group Group 14 Elements -Carbon -Silicon -Germanium -Tin -Lead Silicon is used to make semiconductors for computers and other electronics. Diamond and Graphite are two forms of carbon.

The Nitrogen Group Group 15 Elements -Nitrogen -Phosphorus -Arsenic -Antimony -Bismuth Almost 80% of the air we breathe is nitrogen. Phosphorus is an essential ingredient in healthy teeth and bones.

The Oxygen Group Group 16 Elements -Oxygen -Sulfur -Selenium -Tellurium -Polonium About 20% of the Earth’s atmosphere is oxygen. Sulfuric acid is one the most used chemicals in the world

The Halogens Group 17 Elements -Fluorine -Chlorine -Bromine -Iodine -Astatine The Halogens form salts with the alkali metals. Fluorine is an active ingredient in toothpaste.

The Noble Gases Group 18 Elements -Helium -Neon -Argon -Krypton -Xenon -Radon Helium is used to fill balloons. Neon signs contain noble gases.

Transition Elements Groups 3-12 All transition elements are metals. Group 11 (The Coinage Metals) The Lanthanides The Actinides

The Coinage Metals Group 11 Elements -Copper -Gold -Silver These elements were often used by ancient civilizations to make coins.

The Lanthanides and The Actinides The Lanthanides Soft metals that can be cut with a knife. Were once called rare earth metals. Glass used in computer and TV screens contain Yttirum and Europium. The Actinides All actinides are radioactive. Thorium, Proactinium and Uranium are the only actinides found naturally on earth. Plutonium is used to fuel nuclear power plants.

Let’s See What We Remember What are rows on a periodic table called? What are columns on a periodic table called? Name the two divisions of the periodic table? What can we learn from an element key? How can scientist use the periodic table?

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