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CHEMISTRY - CLUTCH

CH.8 - PERIODIC PROPERTIES OF THE ELEMENTS

CONCEPT: ELECTRON CONFIGURATIONS

In this chapter we will focus on how an element’s ________________________________________ - the distribution of

electrons within the orbitals of its atoms – relates to its chemical and physical properties.

History Lesson: In 1870, Dmitri Mendeleev arranged 65 elements into a ___________________________________ .

• He summarized their behavior in the _______________________________.

• When arranged by atomic mass, the elements exhibit a periodic recurrence of similar properties.

The Electron Configuration

According to the _______________ Principle you first have to totally fill in the lowest energy level before moving to the next.

1s 2s 2p

1s 2s 2p

Hund’s Rule states that electron orbitals that are _______________________ are first half-filled before they are totally filled.  

F (9 electrons)

1s2s$$$$$$2p3s$$$$$$3p$$$$$$3d4s$$$$$$4p$$$$$$4d$$$$$4f5s$$$$$$5p$$$$$$5d$$$$$5f$$$$$5g6s$$$$$$6p$$$$$$6d$$$$$6f$$$$$6g$$$$6h$7s$$$$$$7p$$$$$$7d$$$$$7f$$$$$7g$$$$7h

 

CHEMISTRY - CLUTCH

CH.8 - PERIODIC PROPERTIES OF THE ELEMENTS

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CONCEPT: CONDENSED ELECTRON CONFIGURATION

EXAMPLE: Write the condensed configuration for each of the following elements:

a. Co (27 electrons)

b. Se (34 electrons)

PRACTICE: Write the condensed configuration for each of the following elements:

a. Ag (47 electrons)

 

CHEMISTRY - CLUTCH

CH.8 - PERIODIC PROPERTIES OF THE ELEMENTS

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CONCEPT: INNER CORE & VALENCE ELECTRONS

EXAMPLE: How many core (inner) and valence electrons are present in each of the following elements?

a. P

b. Al

c. Mn

 

CHEMISTRY - CLUTCH

CH.8 - PERIODIC PROPERTIES OF THE ELEMENTS

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CONCEPT: PARAMAGNETISM Vs. DIAMAGNETISM

EXAMPLE: Write the condensed electron configuration of each ion and state if the ion is paramagnetic or diamagnetic.

a. Ni3+

b. S2-

PRACTICE: Write the condensed electron configuration of each ion and state if the ion is paramagnetic or diamagnetic.

a. Cu+

 

CHEMISTRY - CLUTCH

CH.8 - PERIODIC PROPERTIES OF THE ELEMENTS

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CONCEPT: EFFECTIVE NUCLEAR CHARGE & SLATER’S RULES

When looking at any particular electron within an atom it experiences two major forces.

• A(n) ________________ force from the nucleus and a(n) _______________ force from the surrounding electrons.

Now the electron can become shielded from the full force of the nucleus because of the other surrounding electrons.

• Effective Nuclear Charge (Zeff) measures the force exerted onto an electron by the nucleus, and can be calculated

using Slater’s Rules.

e-

e-

e-e-

e-

e-

e-

e-e-

e-

e-

Guidelines for Determining S for an electron: 1. The atom’s electronic configuration is grouped as follows, in terms of increasing n and l quantum numbers:

(1s) (2s,2p) (3s,3p) (3d) (4s,4p) (4d) (4f) (5s,5p) (5d) etc. 2. Electrons in groups to the right of a given electron do not shield electrons to the left. 3. The shielding constant S for electrons in certain groups. For ns and np valence electrons:

a) Each electron in the same group will contribute ______ to the S value. A 1s electron contributes ______ to the S value for another 1s electron.

b) Each electron in n – 1 group contributes ______ to the S value. c) Each electron in n – 2 group or greater contributes ______ to the S value. For nd and nf valence electrons: a) Each electron in the same group will contribute ______ to the S value. b) Each electron in groups to the left will contribute ______ to the S value.

EXAMPLE: Using Slater’s Rules calculate the effective nuclear charge of a 3p electron in argon.

Zeff = Z – S

Z = Nuclear Charge

S = Shielding Constant

CHEMISTRY - CLUTCH

CH.8 - PERIODIC PROPERTIES OF THE ELEMENTS

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PRACTICE: EFFECTIVE NUCLEAR CHARGE & SLATER’S RULES 1

EXAMPLE 1: Using Slater’s Rules calculate the effective nuclear charge of the 4s electron in potassium.

EXAMPLE 2: Using Slater’s Rules calculate the effective nuclear charge of a 3d electron in bromine.

CHEMISTRY - CLUTCH

CH.8 - PERIODIC PROPERTIES OF THE ELEMENTS

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CONCEPT: THE FOURTH QUANTUM NUMBER

An electron in an atom is described completely by a set of four quantum numbers.

• The first three describe its ____________________ and the fourth describes its ________________.

• The ____________ quantum number (mS) helps to discuss the rotational spin of the electron and has values of

either _________ and _________.

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!

According to the _________________________________: no two electrons in the same atom can have the same four quantum numbers.

EXAMPLE: State the electron configuration of boron and list the four quantum numbers of the 1st and the 5th electron.

 

CHEMISTRY - CLUTCH

CH.8 - PERIODIC PROPERTIES OF THE ELEMENTS

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CONCEPT: ATOMIC ORBITAL SHAPE The _______________________ quantum number deals with the shape of the atomic orbital. Each atomic orbital has a

specific shape.

• It uses the variable ___________ and formula _______________________.

Each atomic sub-level has an L value associated with it.

Sublevel s p d f g

L value 0 1 2 3 4

EXAMPLE: Based on the following atomic orbital shape, which of the following set of quantum numbers is correct:

a) n = 8, l = 1, ml = 12

b) n = 8, l = 2, ml = -2

c) n = 8, l = 0, ml = 1

d) n = 8, l = 0, ml = 0

PRACTICE: Based on the following atomic orbital shape, which of the following set of quantum numbers is correct:

a) n = 2, l = 1, ml = +1 , ms = - 1

b) n = 4, l = 1, ml = - 2 , ms = +12

c) n = 3, l = 1, ml = - 1, ms = 0

d) n = 2, l = 1, ml = + 1 , ms = – 12

 

 

 

CHEMISTRY - CLUTCH

CH.8 - PERIODIC PROPERTIES OF THE ELEMENTS

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CONCEPT: TRENDS IN ATOMIC RADIUS

Atomic radius is defined as half the distance between the nuclei in a molecule of two identical elements.

• Generally, it ____________ going from left to right across a period and ______________ going down a group.

ATOMIC RADIUS

EXAMPLE: If the sum of the atomic radii of diatomic carbon is 154 pm and of diatomic chlorine is 198 pm, what is the sum

of the atomic radii between a carbon and a chlorine atom.

PRACTICE: Which one of the following atoms has the largest atomic radius?

A) K B) Rb C) Y D) Ca E) Sr

 

CHEMISTRY - CLUTCH

CH.8 - PERIODIC PROPERTIES OF THE ELEMENTS

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CONCEPT: TRENDS IN IONIC RADIUS

Ionic Size estimates the size of an ion in an ionic compound.

__________________ (POSITIVE IONS) tend to be smaller than their parent atoms.

Lithium ( 3 Electrons)

1s 2s 1s 2s

__________________ (NEGATIVE IONS) tend to be larger than their parent atoms.

Fluorine ( 9 Electrons)

1s 2s 2p 1s 2s 2p

The pattern for ionic size correlates with the following trend when comparing ions with the same number of electrons:

-3 > -2 > -1 > 0 > +1 > +2 > +3

EXAMPLE: Rank each set of ions in order of increasing ionic size.

a) K+ , Ca2+, Ar

b) Sr2+, Na+, I –

c) V5+, S2-, Cl –

 

CHEMISTRY - CLUTCH

CH.8 - PERIODIC PROPERTIES OF THE ELEMENTS

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CONCEPT: TRENDS IN IONIZATION ENERGY

Metals tend to lose electrons to become positive ions called ____________ .

• Therefore they have ____________ ionization energies.

Nonmetals tend to gain electrons to become negative ions called ___________ .

• Therefore they have ______________ ionization energies.

Ionization energy (IE) is the energy (in kJ) required to remove an electron from a gaseous atom or ion.

• Generally, it ________________ going from left to right of a period and ________________ going down a group.

Atom (g) ion+ (g) + e – ∆E = IE1 > 0

Exceptions:

• When in the same period, Group ______ elements have lower ionization energy than elements in Group ______ .

O 1s 2s 2p 1s 2s 2p

N 1s 2s 2p 1s 2s 2p

• When in the same period, Group ______ elements have lower ionization energy than elements in Group ______ .

B 1s 2s 2p 1s 2s 2p

Be 1s 2s 1s 2s  

IONIZATION ENERGY

 

CHEMISTRY - CLUTCH

CH.8 - PERIODIC PROPERTIES OF THE ELEMENTS

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PRACTICE: TRENDS IN IONIZATION ENERGY

EXAMPLE: Of the following atoms, which has the smallest second ionization energy?

a. Al b. Li c. Rb d. Mg e. Be

PRACTICE 1: Of the following atoms, which has the smallest third ionization energy?

a. Al b. Ca c. K d. Ga e. Cs

PRACTICE 2: Which of the following statements is/are true?

a. Sulfur has a larger IE1 than phosphorus

b. Boron has a lower IE1 than Magnesium

c. Magnesium has a higher IE1 than Aluminum

PRACTICE 3: Shown below are the numerical values for ionization energies (IE’s). Match the numerical values with each of

the following elements provided in the boxes.

Na Mg Al Si P S Cl Ar

Numbers: 496, 578, 738, 786, 1000, 1012, 1251 & 1521.

 

CHEMISTRY - CLUTCH

CH.8 - PERIODIC PROPERTIES OF THE ELEMENTS

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CONCEPT: TRENDS IN ELECTRON AFFINITY

Electron Affinity  (EA) is the energy change (in kJ) from the addition of 1 mole of e – to 1 mol of gaseous atoms or ions.

• Generally, it ________________ going from left to right across a period and ______________ going down a group.

Atom (g) + e – ion – (g) ∆E = - EA1

ELECTRON AFFINITY

EXAMPLE: Rank the following elements in order of increasing electron affinity.

a. Cs, Hg, F, S

b. Se, S, Si

PRACTICE: Shown below are the numerical values for electron affinities (EA’s). Match the numerical values with each of the following elements provided in the boxes.

Li Be B C N O F Ne

Numbers: - 328, -141, -122, -60, -27, > 0, > 0, > 0.  

CHEMISTRY - CLUTCH

CH.8 - PERIODIC PROPERTIES OF THE ELEMENTS

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