Lesson 8.2 By: Aran, Atulya, and Mrigas

 Scientists have identified more than 100 elements, including metals, semimetals, and nonmetals. The elements are organized in the periodic table.

 Chemical symbol-an abbreviation of the elements name  Metal-are usually shiny, can be bent or stretched, and can conduct electricity  Noble gas- an element that hardly ever combines with another element to form a compound  Nonmetal- are gases that can not conduct electricity  Periodic table- is a table in which elements are arranged by their properties

 (Metalloids)Semimetal- an element that has properties of both metal and nonmetal elements That is silicon(SI) 

 In 450 B.C. the Greek philosopher Empedocles thought that all matter is made up of four contents: fire, earth,air, and water.  In the middle ages people started to realize there are many more elements than 4.  In the 1600s Robert Boyle argued that these four Greek elements are not really elements.  Later people started to discover there are many other elements

o In 1869 Dmitri Mendeleyev created a way to a arrange and classify elements. He listed the elements in order from increasing mass. o Next he rearranged the elements by putting the ones that have similar properties together. With this format there were a few blank spaces. o Now we use a similar chart (The Periodic Table) o They are basically the same thing because the periodic table is arranged by the properties of elements. o The Periodic Table is called The Periodic Table because Mendeleyev noticed that the element have a repeating pattern.

The different colors tell if the element is to tell if the element is a solid liquid or a gas.

 There are 109 elements listed on the Periodic Table.  Each column is called a group.  Elements in groups have similar properties.  Horizontal rows are called periods.  Two rows are pulled out of the table, this makes the drawing of the table not to wide.

 Iron, gold, nickel, silver, and aluminum are examples of metals  Most metals have luster, or the ability to reflect light  Most metals are conductive, meaning that they can have energy travel through them  Metals are nutrients too. Ex. A banana has potassium which is nutrient that you cells to function properly This is nickelThis is gold This is aluminum

 Magnesium is what make fireworks sparkle. This is magnesium ->

 Examples of semimetals are silicon and boron  Silicon covers 28% of Earth’s surface making it the second most common mineral found on Earth  Silicon is also found in Intel’s computer chips This is boron ->

 Scientist's are still working on names for these new elements  The element’s atomic numbers are 113,115,117,118  The seventh edition of the periodic table is now complete  Element 113 was discovered by the Riken institute, the first element discovered in Asia  Scientists are already trying to discover element 119 and 120

 Plutonium is the most poisonous elements  Plutonium is used for nuclear weapons which are very harmful  Plutonium is radioactive and can accumulate in bones  It’s atomic number is 94 and is scientifically referred to PU

 1 gram of this element can kill 10 million people  The element releases alpha particles which damage organic tissue  Luckily, alpha particles can not penetrate skin

 This metal is extremely reactive.  Even the presence of thin air will make it explode  As you can see scientists need to be very careful around this metal  This metal is a very unsafe

 Fluorine is extremely toxic and will try to react with almost anything  Just 25 of a million concentration of fluorine is potentially lethal  The element can blind and suffocate it’s victim

 Lead was used for paint, utensils, and many other items  Then, people found it is poisonous  Lead can be lethal if you take a high enough quantity  Lead rarely kill people but can lower one’s IQ

 Chromium is used for making car parts, but also has a dark side  It can become a genotoxic carcinogen; something that can harm your DNA  It can also increase your chances of getting cancer  Dangerous levels were found in both the USA and Australia

 4 of the most expensive elements are gold, silver, platinum and plutonium  Platinum is used for making jewelry like rings and necklaces like gold and silver

ANY QUESTIONS?