Periodic Trends

Periodic Trends: Atomic Radius, Ionization Energy, and Electronegativity

By Janet Reichmuth

How "big" an atom: An atom has equal numbers of electrons and protons.

Notice that atoms get bigger from right to left.

​

​Atomic Radius

Reorder

Rank the atoms from SMALLEST to BIGGEST.

• Fluorine (F)

• Oxygen (O)

• Carbon (C)

• Beryllium (Be)

• Lithium (Li)

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

How "big" an atom: An atom has equal numbers of electrons and protons.

Notice that atoms get bigger from top to bottom.

​

​Atomic Radius

Reorder

Rank the atoms from SMALLEST to BIGGEST.

• Helium (He)

• Neon (Ne)

• Argon (Ar)

• Krypton (Kr)

• Xenon (Xe)

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

Multiple Choice

Given the size of the Sulfur (S) atom, which would be the size of an Oxygen (O) atom?

• A

• B

• C

Multiple Choice

Given the size of Sulfur (S), what would be the size of Chlorine (Cl)?

• A

• B

• C

Multiple Choice

Given the size of Sulfur (S), what is the size of Silicon (Si)?

• A

• B

• C

Multiple Choice

Given the size of Sulfur (S), what is the size of Selenium (Se)?

• A

• B

• C

Ionization Energy

​Definition

Ionization energy is the energy required to remove an electron off of the valence shell.

Because valence shells (negative electrons) are farther away from the nucleus (positively charged), it will require LESS energy to remove an electron off of a bigger atom (lower ionization energy)

Multiple Choice

Of those elements listed, which would have the lowest ionization energy value?

• K

• Na

• Rb

• Li

Because metals are, in general, bigger than nonmetals, they will likely have the lower ionization energy value.

​

​Metals vs. Nonmetals

Multiple Choice

Which element will probably have the lowest ionization energy value?

• Mg

• Cl

• Ar

• Si

Electronegativity

Definition

Electronegativity is the probability that an atom will attract electrons (in a bond). Electronegativity has same general trend as ionization energy, but it means something different.

This time, the smaller the atom, the closer the valence shell is to the positive nucleus. Therefore it will attract another electron.

The exception is the noble gases, which have no electronegativity value because they already have full shells and don't pull any more to them.

Multiple Choice

Which element has the LEAST or NO electronegativity value?

• Fluorine (F)

• Neon (Ne)

• Boron (B)

• Lithium (Li)

Multiple Choice

Which of these halogen elements would have the HIGHEST electronegativity value?

• Br

• Cl

• I

• F

Also based on the fact that metals tend to be bigger than nonmetals, nonmetals (except noble gases) will likely have a higher electronegativity value.

​

​Metals vs. Nonmetals

Multiple Choice

Which element likely has the highest electronegativity value?

• Si

• Cl

• Ar

• Mg

Reorder

Order the atoms from LARGEST to SMALLEST

• Cs

• Rn

• Xe

• Na

• Ar

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

Multiple Choice

Which is true?

• Li is more likely to lose an electron than K.

• K is more likely to lose an electron Cs.

• Na is more likely to lose an electron than Li

• Ne is more likely to lose an electron than Li

Multiple Choice

Which atom is MOST likely to gain an electron?

• Cl

• F

• He

• Ne

Match

Match the following

• Electronegativity

• Ionization Energy

• Atomic Radius

Probability of gaining an electron

Energy required to remove an electron.

The size of an atom.

• Probability of gaining an electron

• Energy required to remove an electron.

• The size of an atom.

Drag and Drop

​

Placeholder

are more likely to lose electrons than​

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.

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Metals

nonmetals

Drag and Drop

The bigger the atom, the

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likely an atom will lose an electron.

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more

less

Drag and Drop

The group that will neither gain nor lose an electron is the

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group.

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noble gas

halogen

alkali metal