Exercises

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Section 2-1

Q1-1

What is electromagnetic radiation?

Q1-2

Can you give some examples of types of electromagnetic radiation that you encounter in your daily life? (Visible light is one type)

Q1-3

What properties are used to describe e/m radiation? (What’s the difference between the types of e/m radiation you gave in Q 2?)

Q1-4

What models/theories/ideas do you know about that are used to explain the behavior of e/m radiation?

Section 2-2

Q2-1

Draw a picture of a wave: label the wavelength and the amplitude.

Q2-2

How would you indicate the speed of the wave? What would be the units?

Q2-3

How would you indicate the frequency of the wave? What would be the units of frequency?

Q2-4

Now draw a picture of a wave with the same velocity but twice the frequency. How does doubling the frequency affect the wavelength?

Q2-5

What is the relationship between the velocity of the wave, the wavelength, and the frequency? (check the units)

Q2-6

Now draw two waves – and show what happens if they arrive at the same spot at the same time – in phase.

Show what happens if they arrive out of phase.

Section 2-3

Q3-1

If the intensity of a beam of light is related to the number of photons passing per second, how would you explain intensity using the model of light as a wave? What would change, what would stay the same?

Q3-2

A hydrogen-hydrogen bond (in H₂) requires 7.2x 10^–19 J of energy to break the molecule apart.

A) What frequency of light does this correspond to?

B) What is the wavelength?

C) What consequences does this have in everyday life?

Q3-3

What is the electron configuration for:

A) cobalt (Co)?

B) gallium (Ga)?

Q3-4

Draw a diagram to show how emission and absorption spectra work. Make sure you label your diagram. Also show an example of a high energy emission and a low energy absorption.

Section 2-4

Q4-1

Down a group in the periodic table:

Do you think the atomic radius of Lithium (Li) is…

A) Smaller than sodium (Na)

B) Larger than sodium (Na)

C) Same size as sodium (Na)

D) Don’t Know

Now please explain your reasoning for your answer choice?

Q4-2

If this atom represented Li, draw a circle on top of the atom to show the relative size of Na.

Q4-3

Across a row in the periodic table:

Do you think the atomic radius of Lithium (Li) is…

A) Smaller than neon (Ne)

B) Larger than neon (Ne)

C) Same than neon (Ne)

D) Don’t Know

Now please explain your reasoning for your answer choice?

Q4-4

If this atom represented Li, draw a circle on top of the atom to show the relative size of Ne.

Section 2-5

The size of an isolated atom (the atomic radius) depends on the balance between two opposing forces: the attraction between the negatively charged electrons and the repulsions among the electrons as they get closer together.

Remember Couloumb’s Law

F = k (q₁q₂/r²)

The radius of an atom can change depending on this balance of forces.

Q5-1

This is a representation of an atom using the electron cloud model for an atom of carbon (C). What would the size of an atom of silicon (Si) look like? Draw a circle to represent the relative size of Si.

Q5-2

This is a representation of an atom using the electron cloud model for an atom of carbon (C). What would the size of an atom of nitrogen (N) look like? Draw a circle to represent the relative size of N.

Q5-3

This is a representation of an atom using the electron cloud model. What would happen to this atom if we added an electron to it and kept the number of protons the same? Draw a circle to represent the new size of the ion that would be formed.

Q5-4

This is a representation of an atom using the electron cloud model. What would happen to this atom if we removed an electron to it and kept the number of protons the same? Draw a circle to represent the new size of the ion that would be formed.

Q5-5

Now that you understand how the atomic radius is affected across a row and down a column and when adding an electron and removing an electron, please explain how the attraction between the electrons and nucleus and repulsions between the electrons effect the size of the atomic radius of an atom or ion.

Section 2-6

Q6-1

Here are the first ionization energies for the second row in the periodic table (in kJ/mol)

Li	Be	B	C	N	O	F	Ne
520	899	801	1086	1402	1314	1681	2081

A) Make an argument in you own words why the ionization energy increases in general as you go from left to right across the periodic table.

B) Make an argument in your own words why the ionization energy of boron (B) is lower than that of beryllium (Be).

Q6-2

Here are the first through eighth ionization energies for an element in the third row of the periodic table (in kJ/mol). Which element is it? Then explain your reasoning.

1^st	2^nd	3^rd	4^th	5^th	6^th	7^th	8^th
786	1577	3231	4355	16091	19805	23780	29287

Q6-3

Why are ionization energies evidence for the quantization of energy levels in atoms, as described by the Schrodinger wave mechanical model of the atom?