the electronic structure of atoms...the electronic structure of the atom yfrom classical physics to...

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The Electronic Structure of Atoms

The Electronic Structure of the Atom

From Classical Physics to Quantum Theory (7.1)The Photoelectric Effect (7.2)Bohr’s Theory of the Hydrogen Atom (7.3)The Dual Nature of the Electron (7.4)Quantum Mechanics (7.5)Quantum Numbers(7.6)Atomic Orbitals (7.7)Electron Configurations (7.8)The Building-Up Principle (7.9)

7.1 Light as waves and black body radiation

What properties are used to describe a wave?How are frequency, wavelength and speed of light related?

Figure 7.1, p. 214

7.1 Light as waves and black body radiation

What properties are used to describe a wave?How are frequency, wavelength and speed of light related?What is electromagnetic radiation?

Maxwell (1873), proposed that visible light consists of electromagnetic waves.

Electromagnetic radiation is the emission and transmission of energy in the form of electromagnetic waves.

Speed of light (c) in vacuum = 3.00 x 108 m/s

All electromagnetic radiationλ x ν = c

Figure 7.2, p. 215

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7.1 Light as waves and black body radiation

7.1 Light as waves and black body radiation

What is black-body radiation and how was this important in describing light?

Figure 7.3, p. 216

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7.2 The photoelectric effect – the duality of light

What is the photoelectric effect?How is this explained in terms of light as particles?In terms of particles, what is intensity?In terms of particles, how does increasing the frequency of the light affect the particles?

7.2 Photoelectric Effect

Figure 7.4, p. 218

If light is not composed of particles, then increasing the intensity of light (even of low frequency) should be able to eject an electron.

But it was observed that electrons ejected are dependent on the frequency of the light and not the intensity. Above a certain frequency (called the threshold frequency), as the intensity increases, the number of electron ejected increases.

7.2 Photoelectric Effect

When the photon has a frequency ≥ the energy holding the electron in the metal (the binding energy), the electron is ejected. Any additional energy of the photon (above this) can be given to the electron:

Ephoton = BE + KE

KE(ejected electron) = Ephoton – BE (or W)

Figure 7.4, p. 218

7.3 Bohr’s theory of the hydrogen atom and atomic orbits

What is the atomic emission spectrum for an element?What does the color of the emission lines tell us about the frequency or wavelength of the emitted photon?Why is it not continuous?Describe the atomic emission spectrum for hydrogen

Figure 7.5, p. 220

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atom and atomic orbits

7.3 Bohr’s theory of the hydrogen atom and atomic orbits

What is the atomic emission spectrum for an element?What does the color of the emission lines tell us about the frequency or wavelength of the emitted photon?Why is it not continuous?When is energy absorbed and emitted in Bohr’s model of the atom?

7.3 Bohr’s theory of the hydrogen atom and atomic orbits

Key Definitions:◦ Ground

state or ground level◦ Excited state

or excited level

Figure 7.7, p. 222

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Figure 7.9, p. 223

What is the change in energy for the lowest energy line in the Balmer series for atomic hydrogen?

What is the frequency and wavelength of the corresponding photons?

Table 7.1, p. 223

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atom and atomic orbits

7.4 Dual nature of the electron

Why are electrons limited to these orbits?How can electrons be modeled so this makes sense?Does this new model make sense (based on empirical data)?

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Figure 7.10, p. 225

Figure 7.11, p. 225

7.4 Dual nature of the electron

7.5 Quantum mechanics

How do we model electrons now?What does this mean for the model of the atom?Is it accurate to “dot” electrons in an atomic model?What is Heisenberg’s uncertainty principle?What do quantum numbers tell us?

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In 1926 Schrödinger wrote an equation that described both the particle and wave nature of the e-

Wave function (Ψ) describes:

1. energy of e- with a given Ψ

2. probability of finding e- in a volume of space

Schrödinger’s equation can only be solved exactly for the hydrogen atom. Must approximate its solution for multi-electron systems.

7.5 Quantum mechanics

Atomic Orbitals

Figure 7.15, p. 231

What is a boundary surface diagram?

Quantum numbers (7.6) and atomic orbitals (7.7)

As we consider each quantum number, we will answer:

What is the symbol for the quantum number?What is the rule for which quantum numbers are allowed?What does the quantum number tell us about the atomic orbital or the electrons within these atomic orbitals?What differentiates the different energies of atomic orbitals (within one atom)?

Atomic Orbitals

l = 0

Figure 7.16 p. 231

Atomic Orbitals

l = 1

Figure 7.17, p. 231

Atomic Orbitals

l = 2

Figure 7.18, p. 232

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For an atom with electrons in n = 1, 2, 3, and 4, how many atomic orbitals are totally spherical?

How many have 1 node?

How many have l = 2 and ml = 2?

Are there any atomic orbitals with ml = 3?How many?

Quantum numbers (7.6) and atomic orbitals (7.7)

7.8 Electron configurations

What are electron configurations?How are these determined and written?

Electron configuration

1s1

principal quantumnumber, n

angular momentumquantum number, ℓ

number of electronsin the orbital or subshell

7.8 Electron configurations

7.8 Electron configurations

What are electron configurations?How are these determined and written?How are these modeled in an orbital diagram?

Electron configuration

1s1

principal quantumnumber, n

angular momentumquantum number, ℓ

number of electronsin the orbital or subshell

Orbital diagram H1s1

7.8 Electron configurations

Energy of orbitals in a single electron atom

Energy only depends on principal quantum number n

En = -RH ( )1n2

n=1

n=2

n=3

Figure 7.19, p. 233

Figure 7.24, p. 237

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7.8 Electron configurations

Energy of orbitals in a multi-electron atom

Energy depends on n and l

n=1 l = 0

n=2 l = 0n=2 l = 1

n=3 l = 0n=3 l = 1

n=3 l = 2

Figure 7.19, p. 234

7.8 Electron configurations

What are electron configurations?How are these determined and written?How are these modeled in an orbital diagram?What is the Pauli exclusion principle?What is Hund’s rule?What is diamagnetic vs. paramagnetic?

Paramagnetic (attracted by a magnet)

unpaired electrons

2p

Diamagnetic(slightly repelled by a magnet)

all electrons paired

2pFigure 7.22, p. 236

Table 7.3, p. 242

7.9 The building-up principle

What is the Aufbau principle?What is a noble gas core?How can we use the periodic table to write electron configurations?

Figure 7.25, p. 243

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7.9 The building-up principle

Of the ground state atoms of C, O, and Ne, which are paramagnetic and which are diamagnetic?

Of the period 3 and 4 elements in the ground state, which are paramagnetic and which are diagmagnetic?

Is the silver ion paramagnetic or diamagnetic?

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