HONORS CHEMISTRY

September 18-19, 2013

How do we know what the filling order is? What chemistry tool might we rely on?

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Electron Configurations and the Periodic TableElectron Configurations and the Periodic Table

Valence electron configurations repeat down a group

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Ground state electron configurations

Example: Liatomic number = 3nucleus has 3 protonsneutral atom has 3 electrons

2 electrons in 1s orbital, 1 electron in 2s orbital

1s

2s

Different ways to show electron configuration

Read this “one s two”not “one s squared”

1s

2s

1s 2s

Li 1s2 2s1

Energy level diagram Box notation

Spectroscopic notation

Write the superscript 1.Don’t leave it blank

Using the Periodic Table

The last subshell in the electron configuration is one of these(row #) s (row # – 1) d(row #) p (row # – 2) f

The f-block is inserted into to the d-block

Electron configuration of O Atomic number of O = 8 so neutral atom has 8 e–

Electron configuration of Co Atomic number of Co = 27 so neutral atom has 27 e–

Simplifying electron configurationsShorthand Noble Gas Configuration

Build on the atom’s noble gas core

He 1s2

O 1s22s22p4

O [He]2s22p4

Ar 1s22s22p63s23p6

Co 1s22s22p63s23p64s23d7

Co [Ar]4s23d7

1s 2s 2p

3s 3p

4s 3d

1s 2s 2p

Noble Gases

Far right of the periodic table These elements are extremely unreactive

or inert They rarely form compounds with other

elements

Noble Gas electron configurations

What is the electron configurations for Neon

Abbreviated way to write configurationsStart with full outer shell then add on

Br Ba

Noble Gases

Neon- emits brilliant light when stimulated by electricity – neon signs- 4th most abundant element in the universe.

Helium- light non reactive gas- used balloons- inexpensive, plentiful and harmless

Radon- radioactive gas- can cause cancer- colorless, odorless emitted from for certain rocks underground

Properties of atoms correlate with the number and energy of electrons

Electron configurations are used to summarize the distribution of electrons among the various orbitals

Why are we doing all of this?Why are we doing all of this?

Electron configuration of ions

What is an ion? How many electrons does Cl1- have?

What is the electron configuration for the chloride ion?

How many electrons does Ca2+ have?What is the electron configuration for the calcium

ion? What do you notice?

Why is this important

Valence electrons Electrons in the outermost energy level

Where all the action occurs

The f-block is inserted into to the d-block

Find the electron configuration of Au Locate Au on the periodic table

Find the electron configuration of Au Au [Xe] The noble gas core is Xe

Find the electron configuration of Au Au [Xe]6s2

The noble gas core is Xe From Xe, go 2 spaces across the s-block in the 6th row

6s2

Find the electron configuration of Au Au [Xe]6s24f14

The noble gas core is Xe From Xe, go 2 spaces across the s-block in the 6th row

6s2

Then detour to go 14 spaces across the f-block 4f14

note: for the f-block, n = row – 2 = 6 – 2 = 4

Find the electron configuration of Au Au [Xe]6s24f145d9

The noble gas core is Xe From Xe, go 2 spaces across the s-block in the 6th row 6s2

Then detour to go 14 spaces across the f-block 4f14

note: for the f-block, n = row – 2 = 6 – 2 = 4 Finally go 9 spaces into the d-block on the 6th row 5d9

note: for the d-block, n = row – 1 = 6 – 1 = 5

Practice

Draw the orbital diagram for sulfur.What ion does sulfur want to form and why?

Draw the orbital diagram for Potassium.What ion does sulfur want to form and why?

What does this mean

Properties of atoms correlate with the number and energy of electrons

Atoms like to have full outer shells.

Refer to Atomic Structure Worksheet

Periodic Trends

Preview 4 Periodic Trends

Atomic Size/Radius Ionic Size (**)

Ionization EnergyElectronegativity

2 main factors affect periodic trendsNumber of electron shells (group)Effective Core Charge (ECC) (period)

Term (Refer to Definition Sheet) Effective Core Charge (ECC) 1) The net charge that pulls on the valence electrons in an

atom. The greater the effective core charge, the greater the pull. It is determined by subtracting the number of core electrons from the number of protons in the nucleus For example: Magnesium (label ECC on P.T.)

Term

Electron ShellPattern across the period?Pattern down the group?

Periodic Trends

Atomic radius The distance from the center of an atoms nucleus to it’s outermost electron

Measure of atomic size

Periodic Trends Graph the first 20 elements. What is the trend down a group? Across a Period?

Atomic radius

Periodic Trends

Atomic Radius Group Trend

Increases from top to bottom More energy levels or quantum levels (or “shell”) as

you go down a group – atomic radius increases Period Trend

Increases from right to left All electrons in the same energy level. Increased # of

protons holds them closer to nucleus. Decrease in Effective Core (Nuclear) Charge (ECC)

Calculate ECC for elements in period 2

Table of Table of Atomic Atomic RadiiRadii

Period Period Trend:Trend:Atomic Atomic RadiusRadius

Periodic Trends

Ionic Size

Size of an atom when electrons are added or removed.

Electrons removed atom becomes smaller.

Electrons added atoms become larger

Why? Electron-Electron

Repulsion

Ionic SizeIonic Size

CationsCations

Positively charged ions formed when an atom of a metal loses one or more electrons Smaller than the corresponding atom

AnionsAnions

Negatively charged ions formed when nonmetallic atoms gain one or more electrons

Larger than the corresponding atom

Periodic TrendsGraph the first 20 elements. What is the trend down a group? Across a Period? Ionic Size (label P.T.)

Table of Table of Ion Ion SizesSizes

Ionic Size

Group Trend Increases from top to bottom More energy levels as you go down a group – ionic

size increases Period Trend

Decreases as atoms lose more electrons Increases dramatically as atoms start gaining

electrons, decreases as atoms gain fewer electrons.

Periodic Trends

Ionization Energy Energy needed to remove one of the electrons on an atom’s outer shell.

How strongly does an atom hold it’s outermost electron.

Periodic Trends Graph the first 20 elements. What is the trend down a group? Across a Period?

Ionization Energy

Ionization Energy Group Trends

Increases from bottom to top.The closer outer shell electrons are to the

nucleus the harder they are to remove. Period Trend

Increases from left to right.The more electrons in the outer shell the harder

it is to remove one. Increase in Effective Core Charge (ECC)

Periodic Trend:Periodic Trend:Ionization Ionization EnergyEnergy

Periodic Trends

Electronegativity Is a measure of the level of attraction (pull) an atom exerts on the electrons of another atom.

Ability of an atom to attract electrons

Which elements want to gain electrons the most?

Periodic TrendsGraph the first 20 elements. What is the trend down a group? Across a Period? Electronegativity

Periodic Table of ElectronegativitiesPeriodic Table of Electronegativities

Electronegativity Group Trend

Increases from bottom to topAs radius decreases, electrons are closer to the

nucleus (decrease in number of electron shells) Period Trend

Increases from left to rightThe more electrons in the outer shell (up to 7)

the more the atom wants to attract electrons Exception: Trend does not apply to Noble Gases

Increase in Effective Core Charge (ECC)

Periodic Trend:Periodic Trend:ElectronegativityElectronegativity

Summarize the Trends

Questions???

Summary of Summary of Periodic TrendsPeriodic Trends

Practice

1. Se and Br1. Smallest atom

2. Lowest Ionization Energy

2. P, S, Se1. Largest atom

2. Highest Ionization Energy

3. Cl, Cl1-, Br, Br1-

1. Largest ionic size

4. Mg, Mg2+, Na, Na1+

1. Smallest ionic size

Atomic Properties DefinitionsFor Quiz – Monday Effective Core Charge:

It is the net charge that pulls on the valence electrons in an atom.

The greater the effective core charge, the greater the pull.

It is determined by subtracting the number of core electrons from the number of protons in the nucleus

Valence Electrons Are found in the outermost, valence, electron shell

(Bohr model) of the atom Core electrons

occupy all of the inner electron, core, shells

Atomic Properties Definitions Ionization Energy:

Energy needed to remove an electron from an atom or molecule. The higher the effective core charge and lower the number of

electrons shells, the greater the ionization energy Atomic size

How big (e.g., radius) an atom is Atomic radius is measured from the center of the nucleus to the

valence electron shell. The higher the effective core charge and lower the number of

electron shells, the smaller the atom. Electronegativity

Measure of the level of attraction (pull) an atom exerts on the electrons of another atom.

The higher the effective core charge and lower the number of electron shells, the greater the electronegativity

Homework

Atomic Structure Worksheet 5-3 Worksheet Study for Definition Quiz on Monday

Periodic TableObjective: Students know how to use the periodic table to identify alkali metals, alkaline earth metals, transition metals, metals, semimetals (metalloids), nonmetals, halogens and noble gases.

The Periodic TableThe Periodic Table

Dmitri Mendeleev – credited for the first periodic table in 1869. He had put element names and a few of their

properties on cards and then arranged them in various ways to help his students learn them more easily.

Arranged them so elements in the same column have similar properties.

Reactivity: Metal/NonMetal Trends

ELEMENT CLASSESELEMENT CLASSES

Periodic Song: http://www.privatehand.com/flash/elements.htmlPeriodic Song: http://www.privatehand.com/flash/elements.html

Reading the periodic table

Groups or families – vertical columns

Periods – horizontal rows

Alkali Metals All alkali metals have 1

valence electron They are very reactive Reactivity of these elements

increases down the groupAlkali metals:

http://video.google.com/videoplay?docid=-2134266654801392897#

Potassium, K reacts with water and must be stored in kerosene

Alkaline Earth Metals All alkaline earth metals have 2 valence

electrons Alkaline earth metals are less reactive than

alkali metals The word “alkaline” means “basic”

common bases include salts of the metals Ca(OH)2

Mg(OH)2

Properties of MetalsProperties of Metals Metals are good conductors of heat and electricity

Metals are malleable

Metals are ductile

Metals have high tensile strength

Metals have luster

Transition Transition MetalsMetals

Copper, Cu, is a relatively soft metal, and a very good electrical conductor.

Mercury, Hg, is the only metal that exists as a liquid at room temperature

Properties of Metalloids They have properties of both metals and nonmetals.Metalloids are more brittle than metals, less brittle than most nonmetallic solids Metalloids are semiconductors of electricity Some metalloids possess metallic luster

Silicon, Si – A MetalloidSilicon, Si – A Metalloid Silicon has metallic luster Silicon is brittle like a nonmetal Silicon is a semiconductor of electricity

Other metalloids include:

Boron, B Germanium, Ge Arsenic, As Antimony, Sb Tellurium, Te

NonmetalsNonmetals Nonmetals are poor conductors of heat and electricity Nonmetals tend to be brittle Many nonmetals are gases at room temperature

Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element.

Examples of NonmetalsExamples of Nonmetals

Sulfur, S, was once known as “brimstone”

Microspheres of phosphorus, P, a reactive nonmetal

Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure

HalogensHalogens Halogens all have 7 valence electrons

Halogens in their pure form are diatomic molecules (F2, Cl2, Br2, and I2)

Chlorine is a yellow-green poisonous gas

Noble GasesNoble Gases

Noble gases have 8 valence electrons (except helium, which has only 2)

•they are chemically unreactive

• Colorless, odorless and unreactive; they were among the last of the natural elements to be discovered

Questions?

White Board

Refer to Periodic Trends Review

Electron Configurations and Periodic Trends Write the electron configuration and draw

an orbital diagram for each element Order each group of elements or ions

based on given data for each property requested on card

Use the orbital diagrams to explain the pattern. (does it agree with the “trend”)

Objectives

Use the periodic table to write electron configurations

Use the periodic table to obtain information about the properties of elements