Unit 3 The Periodic Table

Elements and the Periodic Table The Periodic Table is an organized chart of all of the elements in the entire universe For example: Iron (Fe) is an element that is found on Earth. The Iron on earth is identical to the iron atoms found on meteorites. The iron atoms on Mars that make the soil red are the same too.

Elements and the Periodic Table Elements are the building blocks of all matter Elements are the simplest substance in the entire universe. Elements cannot be broken down into other substances by chemical or physical means (except by nuclear means) - Some examples of elements are: Gold (Au), Oxygen (O), Copper (Cu), Calcium (Ca), Iodine (I), Chlorine (Cl), and Neon (Ne) Each element has certain properties which distinguishes it from other elements - These properties are: boiling point & melting point, atomic mass, atomic number, etc.

Organization of the Periodic Table ˚ The periodic table is organized into horizontal rows and vertical columns The horizontal rows are called periods. The vertical columns are called groups. There are 7 periods and 18 groups in the periodic table Groups are numbered 1-18. These numbers refer to the number of electrons in the outer shell of the elements. (This works for the first 20 elements)

Reading the Periodic Table Each square on the periodic table give particular information about the atoms of an element: The number at the top of the square is the atomic number, which is the number of protons in the nucleus of the element The element symbol is an abbreviation for the element name (usually 1-2 letters) The element name is below the symbol The number below the element symbol is the atomic mass. This is the mass of all of the isotopes of the element.

Much information can be derived about an element’s atomic structure just from the information provided in it’s element box. atomic number = number of protons atomic mass number= the total number of protons and neutrons To find the number of neutrons, you take the atomic number and subtract the atomic mass number number of neutrons= atomic number - atomic mass number The number of protons is equal to the number of electrons number of protons= number of electrons

Reading the Periodic Table Metals on the left side of the periodic table and nonmetals on the right side. -The zigzag line on the right side of the table separates metals from nonmetals. Elements touching the zigzag line are called metalloids (except Aluminum which is a metal) Notice: The black bolded elements are solid, the red letters are a gas and there are 5 liquids on the periodic table

Categories of the Periodic Table Metals (general) Hard and shiny 3 or less valence electrons Form positive ions by losing electrons Good conductors of heat and electricity

Metals – (specific) *Reactive metals (alkali and alkaline earth metals)- -Alkali metals- very reactive and are found in the earth’s crust. Group 1 or 1A -Alkaline earth metals- soft and malleable & ductile ( bendable and can be reshaped). Group 2 or 2A *Transition metals (includes poor metals)- Groups 3-12 (or 3B-2B) less reactive than most metals found in foods we eat, for industry (steel, copper), modern technology catalytic converters, and incandescent light bulbs), and alloys (steel and brass). *Rare earth metals (lanthanide series and actinide series)- Bottom of periodic table previously believed to be rare, however as mining improved, scientist realized that they are not rare, just hard to isolate.

NonMetals -Gases or dull, brittle solids -Do not reflect light -Cannot be rolled into wires or pounded into sheets -At room temperature, they can be solids or gases, except Bromine, which is a liquid. -5 or more valence electrons -From negative ions by gaining electrons -Poor conductors of heat and electricity *Noble gases- Group 18, almost never react with other elements -Some are used to make colorful lights *Halogens- Group 17, very reactive nonmetals that form salts when combined with many metals. -Uses: to kill harmful microorganisms in hospitals, to purify drinking water and prevent growth of algae in swimming pools.

Metalloids Appearance will vary 3 to 7 valence electrons Form positive and/or negative ions Conduct better than nonmetals but nor as well as metals Properties of metals and nonmetals Often used in semi-conductors for computer chips NOTE: any element above 92 is too unstable to occur in nature and must be done in a lab, scientist were able to predict existence of elements (neon and germaniuim before they were even discovered Groups 1A-VIIIA (1,2 and 13-18) are called the REPRESENTATIVE ELEMENTS

Classwork: color code the given periodic table Classwork: color code the given periodic table. Represent the following: Alkali metals Alkaline-earth metals Transition metals Rare earths Noble gases Halogens Metals, nonmetals, metalloids