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Unit 5 Periodic Table

Lesson 1: Periodic Table Basics

HISTORY OF THE PERIODIC TABLE

•  Dmitri Mendeleev : 1869 - arranged elements according to increasing atomic mass and similar chemical properties. Left gaps for undiscovered elements.

History of the Periodic Table

•  Henry Moseley: working with Rutherford, discovered nuclear charge (atomic number).

•  Arranged periodic table according to atomic number not mass.

Periodic Law

•  Periodic Law: similar properties recur periodically when elements are arranged according to increasing atomic number.

•  Able to fill in gaps due to predicted properties.

How the table is organized

Periods: Horizontal rows • Equal to the # of energy levels (shells) Groups: Vertical columns • Elements have the SAME # of valence electrons

resulting in similar chemical properties

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How the table is organized Valence Electrons: electrons in the

outermost energy level.

Variable Valence

Reactivity of Elements

• Determined by the # of valence electrons • All atoms (except hydrogen and helium) are stable

when they have 8 valence electrons (full valence shell)

• Called a Stable Octet

Reactivity of Elements

•  The closer to a stable octet, the more reactive the element is

**** Period 1 elements need only 2 electrons to be stable and have a full valence shell

Example

Which two elements have similar chemical properties and why? Fe, K, Li, Be

Practice

•  Pages 6-7 • Add Vocab to page 2

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Lesson 2: Categories and Properties of

Elements

Element Groups

Hydrogen

• Not officially part of a group • Reactive gas (was involved in the explosion of the

Hindenburg) • Nonmetal • Gas at STP

Group 1: Alkali Metals

•  1 Valence electron •  Lose 1 electron to form +1 ions •  Highly reactive metals •  Always combined with something

else in nature…like in salt •  Very soft and can be cut with a

butter knife •  http://www.youtube.com/watch?

v=6ZY6d6jrq-0&feature=channel

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GROUP 2: Alkaline Earth Metals

•  2 valence electrons •  Lose 2 electrons to for +2 ions •  Fairly reactive with water, but less reactive than

alkali metals https://www.youtube.com/watch?

v=DFQPnHkQlZM

GROUP 3-12: Transition Metals

•  varying properties •  variety of uses •  Form colored ions in solution •  Least reactive metals

GROUP: Inner Transition metals

•  Lanthanide series: shiny, metallic elements 57-70, • Actinide series: metallic elements 89-102, • Many computer/technology and energy uses

GROUP 13: Boron Family

• Metals and metalloids • 1 metalloid – Boron • The rest are metals

•  https://www.youtube.com/watch?v=0Hx2DYx4umQ

GROUP 14: Carbon Family

•  Contains metals, nonmetals and metalloids • Carbon – Nonmetal • Si and Ge – Metalloids • The rest metals

GROUP 15: Nitrogen Family https://sciencebob.com/jimmy-kimmel-live-liquid-nitrogen-cloud/ • Contains metals, nonmetals and metalloids

– N and P are nonmetals – As and Sb are metalloids – The rest metals

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GROUP 16: Chalcogens (Oxygen Group)

•  Contains nonmetals and metalloids – O, S, Se are nonmetals – Se (yes, both… tricky guy!), Te, Po are metalloids

GROUP 17: Halogens

•  7 valence electrons • Very reactive, volatile, diatomic, nonmetals • Most reactive nonmetal is F

•  http://www.youtube.com/watch?v=yP0U5rGWqdg

GROUP 18: Noble Gases

•  BORING! The stable electron configurations cause these gases to be inert or non-reactive.

• Have a full valence shell (2 for He, 8 for all others)

METALS

•  except hydrogen, all elements to the left of the “stair steps” ● Malleable (can be hammered or rolled into thin sheets) ● Ductile (can be drawn into a wire) ● Excellent conductors of heat and electricity ● Luster (shiny) ● Lose electrons to form cations ● Solid @ STP (except Hg)

Metals

•  Metals consist of layers of atoms that can slide over each other

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Metals

•  Have a “Sea” of mobile electrons Allows for electrical conductivity

MetalAlloy

•  Alloys such as brass (mixture of copper and zinc) are harder than the original metals Irregularity in the structure helps to stop slipping over each other

NONMETALS

•  elements above and to the right of the “stair steps.” ● Poor conductors of heat and electricity ● Brittle (shatter when struck) ● Dull ● Tend to gain electrons to form anions

METALLOIDS

•  elements that border the stair steps. Some have some properties similar to metals, and some similar to nonmetals, or properties somewhere in between the two ● Semiconductors (Good/moderate conductor) ● Luster (like metals) and Brittle (like nonmetals) ● Used for making computer microchips

PERIODIC TRENDS

•  Certain characteristics show patterns within the periodic table. These are called “periodic trends”.

•  Typically influenced or created by valence electrons.

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PERIODIC TRENDS

•  Certain characteristics show patterns within the periodic table. These are called “periodic trends”

•  Three factors cause the trends: – Coulomb’s Law: attractive forces between protons and electrons increase

as the distance between the protons and electrons decreases – Shielding effect/nuclear force: inner electrons shield the positive nucleus

from “feeling” the outer electrons –  Increasing more energy levels (period number)

•  Focus on Valence electrons

Lesson 3: Periodic Trends: Atomic

Radius

ATOMIC RADIUS

•  SIZE of atom

•  On Table S

Across a Period

•  Trend DECREASES •  Nuclei have greater NUCLEAR pull (larger positive

charges) which pull the electrons closer.

Across a Period Down a Group

•  Trend: increases •  Greater number of energy shells (indictated by the Period #) •  because more energy levels take up more space, and shielding

effect means that the last electrons are not pulled in as tightly

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Down a Group

Why?

•  Atomic radius decreases across a period – (Period, proton, pull)

•  Atomic radius increases down a group – (More electron shells)

Recall

•  Ion Size: Metals – Ion radius SMALLER than atomic radius – metals lose electrons

to form cations

•  Ion Size: Nonmetals – Ion radius LARGER than atomic radius – nonmetals GAIN

electrons to form anions

Lesson 4: Periodic Trends: Ionization

Energy

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Ionization Energy

•  Energy required to REMOVE the most loosely bound electron in the valence shell

•  Located on Table S

Across a Period

•  Trend: Increases across a period •  Stronger PROTON pull makes it more difficult to remove

electrons

Across a Period

•  Trend: Increases across a period •  Stronger PROTON pull makes it more difficult to remove

electrons

Down a Group

•  Trend: Decreases down a group •  Larger atomic radius means less proton pull on outer

electrons (shielding effect)

Ionization Energy

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Practice

•  Completepages15&16•  AddVocabtopage2

Lesson 5: Periodic Trends:

Electronegativity

ELECTRONEGATIVITY

•  Measure of the ATTRACTION for electrons

•  The tendency of an atom to attract electrons to itself while bonding

•  Located on Table S

ELECTRONEGATIVITY

•  Fluorine most electronegative (4.0) •  The closer an atom is to Fluorine, the HIGHER the

electronegativity •  Scale of 0-4

Across a Period

•  Trend: Increases across a period – Exclude Noble Gas

•  Greater proton pull to attract electrons

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Across a Period Down a Group

•  Trend: Decreases down a group •  Larger atomic radius means LESS nuclear pull to attract

electrons to the valence shell (shielding effect)

Electronegativity https://www.youtube.com/watch?v=hePb00CqvP0

Practice

•  Completepages17-19•  Addvocabtopage2•  Designornament–anyexposedpartwillbeadifferentcolor.

Summary of Trends