Unit 01 (Chp 6,7):

Atoms, Electrons,& Periodic Properties

Chemistry, The Central Science, 10th editionTheodore L. Brown; H. Eugene LeMay, Jr.; and Bruce E. Bursten

John D. BookstaverSt. Charles Community College

St. Peters, MO 2006, Prentice Hall, Inc.

Development of Atomic Models

• Indivisible• Identical• React in

fixed ratios+

• + stuff• – electrons

• empty space

NaLi Cu

Rutherford’s atomicmodel didn’t explainproperties of matter(color, reactivity, …)

prism

helium (He)lamp

prism

white light continuous spectrum

elements discrete lines of E & f

Atomic Emission Spectra

(only specific colors of energy & frequency)

A mystery for Niels Bohr.

Hydrogen Emission Spectrum

quantized into specific multiples

ofwavelengths,

electrons occupy only specific levels (or shells)of “quantized” energy(& wavelength & frequency)

Electrons as Waves

but none in between.

(1913–Niels Bohr)Bohr’s Shell Model

Bohr’s Shell Modele–’s emit (–) energy,

move back to

inner levels

(n=5 to n=2)

e–’s absorb (+) energy, move to outer

levels(n=2 to n=5)

EXCITED state

GROUNDstate

∆E

5

242

Which transition shows a light wave of the greatest energy?

32

n=5 to n=2

Photon Energy as Light Waves• Distance between same points on adjacent

waves is the _______________. (m)• Number of Waves passing a given point

per unit time is the ______________. (Hz)(s–1)

and are_________ proportional

wavelength ()

frequency ()

inversely

All light waves move at the same speed, so which color has more energy?

All EM radiation travels at the same speed:the speed of light (c), 2.998 108 m/s. c =

R O Y G B I V

(higher E) (higher ) (shorter )

Low Frequency High Frequency

Electromagnetic Spectrum

Low Energy

High Energy

Photon (Light) Calculations

Given wavelength () of light, one cancalculate the energy (E) of 1 photon of that light:

E = hc = (given on Exam)

HW p. 253#14,25ab,26,34

, (inverse) E , (direct)

↔ ↔ E

2.998 108 m/s 6.626 10–34 J•s(constants)

Schrödinger Wave Equation:

Heisenberg Uncertainty Principle: the more precisely a particle’s motion is known,

the less precisely itsposition is known.(particle)

(wave)

probable 3-D regions (ORBITAL shapes) orsublevels occupied by electrons in each fixed level.

(1926–Schrodinger & Others)Quantum Mechanical Model

s , p , d , f

1803 DaltonAtomic Theory

1904 ThomsonPlum Pudding

1911 RutherfordNuclear Model

1913 BohrShell Model

1926 Quantum Mechanical Model

Development of Atomic Models

1. (Shell) principle energy level (n) (1,2,3,4 …)

2. (Sub-shell) shape

3. (Orbital) 3-D arranged

4. (Electron) spin up/down

Where are the electrons really?

x z

s (1) p (3)(not rings)

d (5) f (7)

y

HW p. 255#57,60

Electron Configuration

1s2 2s2 2p4

energy level

(shell, n)

1s2 2s2 2p4

Orbital Notation

+8

Oxygen (O)

Electron Configuration

1s2 2s2 2p4

energy level

(shell, n)

1s2 2s2 2p4

orbital shape

(s,p,d,f)

Orbital Notation

+8

Oxygen (O)

Electron Configuration (arrangement)

1s2 2s2 2p4

energy level

(shell, n)

1s2 2s2 2p4

orbital shape

(s,p,d,f)

# of e–’s in each orbital

+8

1s2 2s2 2p6 3s1Na

1s2 2s2 2p6 3s2 3p1

[Ne] 3s2 3p5

noble gas core

Al

Cl

Oxygen (O)

Orbital Notation

How many valence e–’s?

6

(outer level)

2s21s2 2p6 3p63s2 4p24s2 3d10

(3d fills after 4s)

Aufbau: Fill lowest energyorbitals first.

+nucleus

Pauli Exclusion:no e–’s same props (opp. spin) (↑↓)

Hund:1 e– in equal orbitals before pairing()

?

Electron Configuration of IonsIon E-

Con

(i) F–

(ii) Ca2+

(iii) S2–

(iv) Na+

(v) Al3+

1s2 2s2 2p6 [Ne]

1s2 2s2 2p6 3s2 3p6 [Ar]

1s2 2s2 2p6 3s2 3p6 [Ar]

1s2 2s2 2p6 [Ne]

1s2 2s2 2p6 [Ne]

Which ions are isoelectronic?F– , Na+ , Al3+ Ca2+ , S2–

List 3 species isoelectronic with Ca2+ & S2–.P3– , Cl– , Ar, K+ , Sc3+ , Ti4+, V5+, Cr6+, Mn7+

• Paramagnetic:

species are attracted by a magnet (caused by unpaired electrons).

Fe: [Ar] ↑↓ ↑↓ ↑ ↑ ↑ ↑ 4s 3d

• Diamagnetic:

species are slightly repelled by magnets

(caused by all paired electrons)

Zn: [Ar] ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ 4s 3d

Other Aspects

(“di-” is 2)

Other Aspects• d block metals lose their outer s electrons

before any core d electrons to form ions.

Fe 1s2 2s2 2p6 3s2 3p6 4s2 3d6

Fe2+ 1s2 2s2 2p6 3s2 3p6 3d6

Fe3+ 1s2 2s2 2p6 3s2 3p6 3d5

• d block (trans. metals) have colored ions due to light excited e– movement in d orbitals

HW p.255 #74

Spectroscopy

EM REGION SPECTROSCOPIC TECHNIQUE APPLICATION

TV/Radio (Rf) Nuclear magnetic resonance (NMR) Molecular Structure by changes in nuclear spin.

Infrared IR (bond vibrations) Molecular Structure by different bond vibrations

Visible/UV Vis/UV Atomic Emission Spectra (lines of frequencies/colors)

Electron Transitions between energy levels

X-ray PES (Photoelectron Spectroscopy) Electronic Config. in atoms (by attraction & )

6 min Video Explanation of PES: https://www.youtube.com/watch?v=NRIqXeY1R_I&feature=player_detailpage

higher peak = more e–’s

Photoelectron Spectroscopy (PES)R

elat

ive

# o

f e

– ’s

Binding Energy

Which peak is H and which is He?

He

H

...or Ionization Energy(required to remove e–’s)

1s2

1s1

6 5 4 3 2 1 0

further left = more energy required(stronger attraction

due to more protons)

(MJ/mol)

higher peak = more e–’s

Photoelectron Spectroscopy (PES)R

elat

ive

# o

f e– ’s

Binding Energy

Which peak is H and which is He?

He

H

...or Ionization Energy(required to remove e–’s)

1s2

1s1

6 5 4 3 2 1 0

further left = more energy required(stronger attraction

due to more protons)

(MJ/mol)

1s2 2s2

2p6?

Identify the element

& e-config

Ne

PES (A)

PES (B)

1s2 2s2

2p6

3s2

3p6

3d10

4s2 4p2

?4s1

n = 1 n = 2 n = 3 n = 4

Identify element

(A)

Identify element

(B)

Ge

K

PES (X)

Write the complete electron configuration of element (X), and identify the element.

1s2 2s2

2p6

3s2

3p6

3d10

4s2 4p1

1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p1 Ga1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1 WS 3a

Chemistry, The Central Science, 10th editionTheodore L. Brown; H. Eugene LeMay, Jr.; and Bruce E. Bursten

John D. BookstaverSt. Charles Community College

St. Peters, MO 2006, Prentice Hall, Inc.

Unit 1 (Chp 7):

Periodicity…or…

Periodic Trends in Atomic Properties

Periodic Trends

• We will explain observed trends in

Atomic (and Ionic) Radius

Ionization energy

Electronegativity

size

lose e–

attract e–

Zeff & shielding(explains ALL periodic trends and properties)

• effective nuclear charge, (Zeff):

Zeff & Shielding

• shielding, (S):

(core e–’s)

Na atom

Z = +11

Zeff = +1

inner core e–’s shield valence e–’s from nuclear attraction.

Z = nuclear charge (+proton’s)S = shielding

+11

Zeff = Z − S

attraction

shielding

Zeff

Atomic Radius

-due toincreasing shielding(more energy levels)

increases d

ow

n a g

rou

p

-due to increasing Zeff

(more protons)

decreases across a period

att.

=shield

Zeff

att.

shield

=Zeff

Ionic Radius

•Cations are smaller than neutral atoms.outermost electron(s) are

removed and loses a shell

core shell closer to nucleus

inner e–’s shielded (Zeff)

e–e–

Na+

Ionic Radius

• Anions are larger than their parent atoms.electrons are added and

repulsions are increased

(=Zeff & =shielding)

Arrange the following species by

increasing size: Ar, K+, Ca2+, S2–, Cl–

Ca2+ < K+ < Ar < Cl– < S2–

e–e–

e–

Ionization Energy (IE)

• more energy to remove each electron• IE1 < IE2 < IE3, …

• once all valence e–’s are removed, the next e– is on an inner level with attraction (shielding & Zeff).

• energy required to remove an electron

look for a huge jump in IE

huge jump in IE4 b/c 4th e– on inner level(must have 3 valence e–’s)

increases across a period WHY?d

ecreases do

wn

a gro

up

Trends in First IE

Trends in First IE

-due to increasing Zeff

(more protons) att.

=shield

Zeff

increases across a period

IE tends to…

decreases d

ow

n a g

rou

p-due toincreasing shielding

(more energy levels)

att.

shield

=Zeff

5B & 8O exceptions to trend.

Does this graph support your understanding of IE1 and the Periodic Table?

Why?

increase across period(Zeff , =shielding)1st IE tends to…

Exceptions to 1st IE Trend

1st IE of 5B < 4Be b/c… The e– in 2p orbital of B is higher energy than the e– in 2s orbital of Be ; less energy needed to remove 1st e– in B. ORThe 2p e– of B has more shielding by the 2s e–’s.

↑↓2s

↑↓2s

↑2p

BeB

↑ ↑

increase across period(Zeff , =shielding)1st IE tends to…

Exceptions to 1st IE Trend

1st IE of 8O < 7N b/c… The paired e– in 2p orbital of O experiences e–---e– repulsion requiring less energy to remove 1st e– in O.

↑↓2s

↑↓2s

↑↓2p

NO ↑ ↑↑2p

Trends in Electronegativity (EN)-ability of an atom to attract electrons when bonded (sharing e–’s) with another atom.

decreases d

ow

n a g

rou

pincreases across a period-due to increasing Zeff

(more protons)

att.

=shield

Zeff

-due toincreasing shielding

att.

shield

=Zeff

Periodic TableElements arranged by…

atomic #

Periodic Table

Metals on the left(80% of all elements)

Nonmetals on the right(except H)

Periodic Table

Metalloids border the stair-step(Al is metal)

Periodic Table

• Rows on the periodic chart are called _______.

• Columns are _______.

• Elements in the same ______ have similar _________________.

periods

Periodic Table

groups

groupchemical properties

(shell, n)(energy level)(# val. e–’s)

Group Names (1, 2, 17, 18)

1 2 17 18

Group 1: Alkali Metals

• soft, metallic solids

• lowest IE’s (lose e–’s easily) Zeff

• more reactive down a group b/c…shielding causesatt. & IE,easier to lose e–

video clip

Group 2: Alkaline Earth Metals

• low IE’s, but not as low as alkali metals.• less reactive than alkali metals (Zeff , att. & IE),

but more reactive down the group.(shielding causes att. & IE)

Group 17: Halogens

•high IE’s (don’t lose e–’s easily) (Zeff , att.)

• large EN (attract e–) (Zeff , att.)

•more reactive at top of a group b/c…shielding causes att. & EN,

easier for nonmetals to attract e–

Group 18: Noble Gases

• UNREACTIVE (mostly) b/c… • HUGE IE’s b/c……• Monatomic gases

Zeff , att. (no lose e–), and filled valence shell (no gain e–)

Metals vs. NonmetalsTable 7.3 p. 277 (in book)

Metalloids:•characteristics of metals & nonmetals.•Silicon is shiny, but brittle and is a semi-conductor.Si

Periodic Trends (Summary)Electronegativity

Ele

ctro

nega

tivi

ty

Atomic radius

Can you explain all of this in terms of p’s and e’s?Zeff & shielding

Periodicity:

soft highly reactive metals

harder less reactive metals

highly reactive nonmetals

nonreactive nonmetals

WS Periodicity

WS 7a

–repeating pattern of properties

HW p. 292 #13,28,38,46