Chapter 5 – The Periodic Table

the Father of Modern Chemistry 5.1 Organizing the Elements Antoine Lavoisier (1743-1794) the Father of Modern Chemistry In 1789, he grouped the elements into categories metals nonmetals gases earths for 80 years scientists tried to classify elements, but no one way accounted for the variety of elements known

by the 1860’s, there were 63 known elements 5.1 Organizing the Elements Dmitri Mendeleev (1834-1907) a chemist and teacher by the 1860’s, there were 63 known elements used the game of solitaire as the inspiration for his organization of the elements

on each card, he listed the element’s name, mass and properties 5.1 Organizing the Elements on each card, he listed the element’s name, mass and properties lined up cards in rows in order of increasing mass kept elements with similar properties in the same column the chart was periodic (repeating)

5.1 Organizing the Elements periodic table – an arrangement of elements in columns, based on a set of properties that repeat from row to row

? 5.1 Organizing the Elements 1 2 3 4 Which dot should replace the question mark? 1 2 3 4

Mendeleev left gaps in the table 5.1 Organizing the Elements Some elements would not fit in certain spots because they didn’t have the right mass and / or properties Mendeleev left gaps in the table

Named a predicted element “eka-aluminum” 5.1 Organizing the Elements Mendeleev went on to give names to elements he predicted would be discovered and fill in the blanks Named a predicted element “eka-aluminum” Later an element was discovered that matched the properties of eka-aluminum. (named Gallium) With a periodic table the chemical behavior of elements can be explained and predicted

5.2 The Modern Periodic Table In the modern periodic table, elements are arranged by increasing atomic number (number of protons)

each row is called a period 5.2 The Modern Periodic Table each row is called a period the number of elements per period varies because the number of available orbitals varies

each column is called a group 5.2 The Modern Periodic Table each column is called a group the elements within a group have similar properties the pattern of repeating properties is the periodic law

H 1 atomic number Hydrogen 1.0079 element symbol element name 5.2 The Modern Periodic Table atomic number H Hydrogen 1 1.0079 element symbol element name atomic mass atomic mass unit (amu) – one twelfth the mass of a carbon-12 atom

Distribution of Chlorine 5.2 The Modern Periodic Table Cl Chlorine 17 35.453 What is the atomic mass of chlorine? 35.453 amu Distribution of Chlorine Isotopes in Nature Isotope Percentage Atomic Mass Chlorine-35 75.78% 34.969 Chlorine-37 24.22% 36.966 the atomic mass is a weighted average of these values

5.2 The Modern Periodic Table

elements are first classified as solids, liquids, or gases 5.2 The Modern Periodic Table elements are first classified as solids, liquids, or gases

elements are then classified as to whether or not they occur naturally 5.2 The Modern Periodic Table elements are then classified as to whether or not they occur naturally all but two elements in the first 92 elements occur naturally

then classified as metals, nonmetals, and metalloids 5.2 The Modern Periodic Table then classified as metals, nonmetals, and metalloids

most of the elements are metals 5.2 The Modern Periodic Table most of the elements are metals - good conductors - malleable and ductile - solid at room temperature (except Mercury) - some very reactive

transition metals are groups 3 through 12 5.2 The Modern Periodic Table transition metals are groups 3 through 12 tend to form compounds with distinctive colors

other elements are called nonmetals 5.2 The Modern Periodic Table other elements are called nonmetals - poor conductors - the solids are brittle - many are gases at room temperature - some are reactive, some aren’t

and still other elements are called metalloids 5.2 The Modern Periodic Table and still other elements are called metalloids - properties of metals and nonmetals - conductivity varies with temperature

5.2 The Modern Periodic Table elements become less metallic and more nonmetallic going across a period from left to right

5.2 The Modern Periodic Table How did some ancient civilizations preserve their dead? What are two types of information that scientists discover by examining mummies? What evidence led forensic scientists to suspect Tutankhamen, also known as King Tut, might not have died from natural causes? List features that scientists found in the bones of mummies in Chile. What do forensic scientists suspect to be the causes of the features found in these mummies?

5.3 Representative Groups Is hydrogen a metal? It is not. Why, then, is it grouped with the metals in the periodic table? It shares an electron configuration similar to other elements in Group 1

valence electron – an electron in the highest energy level of an atom 5.3 Representative Groups The number of the A groups tells the number of valence electrons in an atom. valence electron – an electron in the highest energy level of an atom Elements in groups share properties because they have the same number of valence electrons

5.3 Representative Groups In class assignment to be collected and graded: Read pages 140-145. Each section discusses one of the A-groups on the periodic table. You are to do the following on a separate sheet(s) of notebook paper. All your pages are to be stapled and collected when you are finished. Put a heading for each new section, it should contain both the A-Group name and number. Under each heading put: The number of valence electrons A list of the elements within the group (both name and symbol) A comment on the reactivity of the elements within the group Two elements or compounds containing the elements from the group and how they are used. Two questions you formulate about each group based on what you have read. When finished, do the questions on page 145 1-12 (complete sentences)

Group 1A – Alkali Earth Metals 5.3 Representative Groups Group 1A – Alkali Earth Metals One valence electron Found in nature as compounds Reactivity increases going from top to bottom of group Many react violently with water Very soft (can cut with a knife) Video 1 Video 2 Video 3 Video 4 Video 5 Video 6

Group 2A – Alkaline Earth Metals 5.3 Representative Groups Group 2A – Alkaline Earth Metals Two valence electrons Harder than Group 1A elements

Three valence electrons 5.3 Representative Groups Group 3A – Boron Family Three valence electrons Aluminum is the most abundant metal in the Earth’s crust

Four valence electrons Get more metallic as go down group 5.3 Representative Groups Group 4A – Carbon Family Four valence electrons Get more metallic as go down group Most compounds in the body contain carbon (the exception is H2O) Silicon is the 2nd most abundant element in the Earth’s crust

Group 5A – Nitrogen Family 5.3 Representative Groups Group 5A – Nitrogen Family Five valence electrons 78% of the atmosphere is nitrogen

Oxygen is the most abundant element in the Earth’s crust 5.3 Representative Groups Group 6A – Oxygen Family Six valence electrons Oxygen is the most abundant element in the Earth’s crust Sulfur was one of the first element’s discovered

Seven valence electrons All are highly reactive 5.3 Representative Groups Group 7A – The Halogens Seven valence electrons All are highly reactive Fluorine the most reactive, Chlorine a close second React with metals to form compounds called salts

Group 8A – The Noble Gases 5.3 Representative Groups Group 8A – The Noble Gases Eight valence electrons, except Helium (has 2) Colorless, odorless Extremely unreactive Used in “neon” lighting

5.3 Representative Groups