chapter 6 the periodic table and periodic law. section 6.1 development of the modern periodic table
TRANSCRIPT
Chapter 6Chapter 6
The Periodic Table The Periodic Table and Periodic Lawand Periodic Law
Section 6.1Section 6.1Development of the Development of the
Modern Periodic TableModern Periodic Table
ObjectivesObjectives
• Trace the development and Identify key features of the periodic table.
HistoryHistory• 1790s, French scientist Lavoisier
•23 elements
• 1800s: electricity and spectrometer
John NewlandsJohn Newlands• Patterns of the periodic table• Law of octaves • Elements on the eights had similarities
Meyer & MendeleevMeyer & Mendeleev
• 1869-Meyer and Mendeleev: connection between atomic mass and properties
• Mendeleev published it first– Left holes of undiscovered elements– Predicted properties of undiscovered
elements- Sc, Ga, Ge
MoseleyMoseley• Problems with Mendeleev
•Rows by increasing atomic mass
• Moseley used atomic number instead
The Periodic LawThe Periodic Law
• There is a periodic repetition of chemical and physical properties of the element when they are arranged by increasing atomic number.
The Modern Periodic TableThe Modern Periodic Table
• Horizontal rows- periods• Vertical columns- groups or families
• Groups 1A through 8A = Representative Elements – Wide range of chemical and physical
properties
• Groups 1B through 8B = Transition Elements
Metals
– shiny, smooth– solid room temperature– good conductors of heat and
electricity
Alkali MetalsAlkali Metals
• Alkali Metals= 1A (excluding hydrogen) – highly reactive
Alkaline Earth MetalsAlkaline Earth Metals
• Alkaline Earth Metals= 2A– highly reactive (not
as much as 1A)
TransitionsTransitions• Transition metals
– Group B elements contained in the D block of the table
• Inner transition metals – the lanthanide and actinide series – F block
NonmetalsNonmetals– Generally a gas or a brittle, dull-looking solids– Poor conductors
• Halogens=7A – REALLY REACTIVE
• Noble Gases= 8A – unreactive and stable (all valence electrons
are filled)
MetalloidsMetalloids
– contain the physical and chemical properties of both metals and nonmetal
HomeworkHomework•Section 6.1 Assessment
–1-6 on page 158
Reactivity TrendsReactivity Trends
• Increases down the table for the metals
• Decreases down the table for the nonmetals
Section 6.2Section 6.2Classification of the Classification of the
ElementsElements
ObjectivesObjectives• Explain why elements in the same
group have similar properties• Identify the four blocks of the
periodic table based on electron configuration
Valance ElectronsValance Electrons• The properties of each element in
each group are similar because they have the same number of valence electrons
Valence Electrons and Valence Electrons and Period NumberPeriod Number
• Energy level of valence electrons = period on the table
• Example: Lithium: period 2, valence electron in 2nd energy level (1s22s1)
Valence Electrons and Valence Electrons and Group NumberGroup Number
• Group number (1A-8A) = number of valence electrons
Putting it TogetherPutting it Together• Oxygen is in the 3rd period and in
group 6A.
– Oxygen’s valence electrons are located in the ____ energy level.
– Oxygen has ___ valence electrons.
S,P,D, and F BlocksS,P,D, and F Blocks• 4 different energy sublevels:
s, p, d, and f • S block= 1A and 2A
– holds max of 2 electrons
• P block= 3A through 8A– max holds 6 electrons– S block must fill before P block can fill– Noble gases are stable because of filled
S and P blocks
S,P,D, and F Blocks S,P,D, and F Blocks Continued…Continued…
• D block = transition metals – max of 10 electron
• F block= inner transition metals– unpredictable manner of filling– max of 14 electrons
Reactivity TrendsReactivity Trends
• Increases down the table for the metals
• Decreases down the table for the nonmetals
HomeworkHomework• Page 162, #10-15
Periodic Trends: Atomic Periodic Trends: Atomic RadiusRadius
• For metals, atomic radius = ½ distance between adjacent nuclei in a crystal element
• For nonmetals, atomic radius = ½ distance between nuclei of identical atoms that are chemically bonded
Periodic Trends: Atomic Periodic Trends: Atomic RadiusRadiusDECREASES
INCREASES
Atomic RadiusAtomic Radius• The increase from top to bottom
is due to adding electron shells.
• The decrease from left to right is due to increased nuclear charge as you move to the right, which draws electrons closer to the nucleus.
Periodic Trends: Ionization Periodic Trends: Ionization EnergyEnergy
• Ionization energy= energy required to remove an electron from a gaseous atom
• Octet rule = atoms tend to gain lose or share electrons to acquire a full set of 8 valence electrons
Periodic Trends: Ionization Periodic Trends: Ionization EnergyEnergyINCREASES
DECREASES
Periodic Trends: Periodic Trends: Electronegativity Electronegativity
• Electronegativity= relative ability of an atom to attract electrons in a chemical bond.
ElectronegativityElectronegativity• Arbitrary units called Paulings (after
Linus Pauling) are used to express electronegativity.
• Electronegativity increases from left to right across a period and from top to bottom down a group.
Periodic Trends: Periodic Trends: ElectronegativityElectronegativity
INCREASES
DECREASES