chemistry chapter 4 arrangement of electrons in atoms southern boone county hs william palmer

CHEMISTRY

Chapter 4

Arrangement of Electrons in Atoms

Southern Boone County HS

William Palmer

CHEMISTRY CHAPTER 4

Properties of Light

Electromagnetic Radiation

Wavelike behavior

Visible light

X-Rays

Ultraviolet

Infrared

CHEMISTRY CHAPTER 4

CHEMISTRY CHAPTER 4

Wavelength-Distance between corresponding parts of a wave (lambda)

Frequency-Number of waves that pass a point in a given time (v). Measured in hertz (HZ)

CHEMISTRY CHAPTER 4

c is speed of light 186,000 miles/secfrequency X wavelength = speed of lightc=f λλ =c/ff=c/ λSo what?As wavelength increases, frequency

decreasesAs wavelength decreases, frequency

increases

CHEMISTRY CHAPTER 4

Photoelectric Effect-emission of electrons when a light shines on a metal.

CHEMISTRY CHAPTER 4

Photoelectric Effect-emission of electrons when a light shines on a metal.Light must be of a high frequency.Hard to explain with wave theory of light.

CHEMISTRY CHAPTER 4

Max Planck (1900)

Objects emit light in small packets called quanta.

The Quantum Theory

CHEMISTRY CHAPTER 4

Quantum of energy is the smallest amount of energy that can be lost or gained by an atom.

CHEMISTRY CHAPTER 4

Einstein (1905)

Electromagnetic radiation has a dual wave-particle nature!

WOW

CHEMISTRY CHAPTER 4

HYDROGEN ATOM LINE-EMISSION SPECTRUM (WOW THAT IS A MOUTHFUL)

What does it mean?

CHEMISTRY CHAPTER 4

What does it mean?When a current is passed through a gas light is emitted.In hydrogen gas, some of the light is lost-not in spectrum.This indicates that a specific amount of energy from the light was absorbed by the atom.

CHEMISTRY CHAPTER 4

Neils Bohr (1913)Electrons in orbitsDifferent electrons have different energy levels (like rungs on a stepladder)When in orbit an electron has constant energyWhen electron goes to a higher energy state it moves up the ladder (absorption)When electron goes to a lower energy state it moves down the ladder (emission)

CHEMISTRY CHAPTER 4

Questions 1-5 page 103

Try questions1-3, page 110

PPT not ready yet…

CHEMISTRY CHAPTER 4, sec 2

HEISENBURG UNCERTAINY PRINCIPLE-It is hard to tell the location of an electron.

Or….in formal words….


HEISENBURG UNCERTAINY PRINCIPLE-It is impossible to simultaneously tell the position and velocity of an electron or other particle. You can tell one but not the other.


QUANTUM NUMBERS AND QUANTUM ORBITALSQuantum numbers specify the properties of atomic orbitals and the properties of electrons in orbitals.


PRINCIPAL QUANTUM NUMBER (n)

Main energy level occupied by an electron.

Positive integers1, 2, 3, 4 ….


AS n INCREASES, THE ELECTRON’S ENERGY AND DISTANCE FROM THE NUCLEUS INCREASE.


So, which has more energy-quantum number 4 or quantum number 6?

Which is closer to the nucleus of the atom?


There are four types of Quantum Numbers:

1) Main Quantum Number

2) Angular Momentum Quantum Number

3) Magnetic Quantum Number

4)Spin Quantum Number


Angular Momentum Quantum Number (l)-Indicates the shape of the orbit.


S ORBITALS


P ORBITALS


D ORBITALS


F ORBITALS


Magnetic Quantum Number (m)-Indicates the orientation of the orbit around the nucleus.


Spin Quantum Number (-1/2, +1/2)-Indicates the fundamental spin state of the electrons of the orbit around the nucleus.


s = sphere

p = dumbbell

d= complex dumbbell

f=very complex shape


PRINCIPAL

QUANTUM

NUMBER

(n)

SUBLEVELS

IN MAIN

ENERGY LEVEL

ORBITALS

PER

SUBLEVEL

ORBITALS

PER ENERGY LEVEL

ELECTRONS

PER

SUBLEVEL

ELECTRONS PER MAIN ENERGY

LEVEL

1 S 1 1 2 2

2 S 1 4 2 8

2 P 3 4 6 8

3 S 1 9 2 18

3 P 3 9 6 18

3 D 5 9 10 18

4 S 1 16 2 32

4 P 3 16 6 32

4 D 5 16 10 32

4 F 7 16 15 32


Try questions1-3, page 110


Electron ConfigurationThe goal of this section is to figure out how electrons are arranged in an atom.

There are three rules.


Electron ConfigurationRule 1: Aufbau Principle-an electron occupies the lowest energy orbital that can receive it.


Electron Configuration

Rule 2: Pauli Exclusion Principle-No two electrons can have the same set of quantum numbers.


Electron ConfigurationRule 3: Hund’s Rule –Orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron.


Sample ProblemThe electron configuration of Boron is 1s22s22p1.

How many electrons are present in an atom of Boron? (2+2+1 = 5 electrons)

What is the atomic number of Boron? (protons = electrons so with 5 electrons there are 5 protons so Atomic No. of Boron = 5)


Sample ProblemThe electron configuration of Boron is 1s22s22p1.

Write the orbital notation for Boron.

↑↓ ↑↓ ↑

1s 2s 2p


Practice ProblemThe electron configuration of Nitrogen is 1s22s22p3.

1. How many electrons are in Nitrogen?

2. What is the atomic number of Nitrogen?

3. Write the orbital notation for Nitrogen.


Practice ProblemThe electron configuration of Fluorine is 1s22s22p5.

1. How many electrons are in Fluorine?

2. What is the atomic number of Fluorine?

3. Write the orbital notation for Fluorine.


Second Period ElementsSee chart page 116

Third Period ElementsSee chart page 117

Fourth Period ElementsSee chart on page 118

FIGURE 19, PAGE 116, IS WHERE YOU LEARN HOW THE ELECTRONS FILL THE

ORBITALS


FIGURE 19, PAGE 116, IS WHERE YOU LEARN HOW THE ELECTRONS FILL THE

ORBITALS


Sample ProblemWrite the electron configuration for a Rubidium atom. (Atomic Number = 37)

1s22s22p63s23p63d104s24p65s1

Write the Noble-gas configuration for Rubidium.

[Kr] 5s1


Sample ProblemIdentify the elements in the second, third, and fourth periods that have the same number of highest energy level electrons as Rubidium.

Rubidium has one electron in its highest energy level…(the 5th). Other elements that have one electron in their highest energy level are: Li, Na, and K.


Practice ProblemWrite the electron configuration and Noble gas notation for a Barium atom. (Atomic Number = 56)

1s22s22p63s23p63d104s24p64d105s25p66s2


Practice ProblemWrite the electron configuration and Noble gas notation for a Barium atom. (Atomic Number = 56)

1s22s2p63s23p63d104s24p64d105s25p66s2

[Xe] 6s2


Practice ProblemWrite the Noble gas notation for a Gold atom. (Atomic Number = 79)

1s22s2p63s23p63d104s24p64d105s25p66s2

[Xe] 4f145d106p1


Practice ProblemIdentify the elements in the sixth period that have one unpaired electron in their 6s level.

Au, Cs, Pt


Practice ProblemLet’s try the work sheet on Chap 4, sec 3.

chemistry chapter 4 arrangement of electrons in atoms southern boone county hs william palmer

Documents

chemistry chapter

quantum theory slide

wow slide

quantum of energy

spin quantum number

energy quantum number

frequency increases

ladder emission slide