Periodic Trends

As you move down a group, atomic radius increases because - 

• you add more and more neutrons
• you add more and more protons
• you add more and more shells (energy levels)
• you add more atomic mass

The atom with the largest atomic radius in Group 18 (The Noble Gases) is - 

• Ar
• He
• Kr
• Rn

As you move across the periodic table from left to right, the atomic radius decreases.  This is because - 

• the number of protons increases, so attraction to electrons increases
• the number of energy levels increases
• the number of electrons increases
• the atomic mass increases

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The atom with the largest atomic radius in Period 4  is - 

• K
• Kr
• Fe
• Fe

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The Br^- anion is larger than the Br atom because - 

• Br^- has more electrons than Br, and more electrons repel each other
• Br has more electrons than Br^-, and more electrons repel each other
• Br^- has more protons, so it has more attraction for its electrons
• Br has more protons, so it has more attraction for its electrons

If two ions are isoelectronic (i.e. Na⁺ and Mg²⁺), which one will be smaller in radius, and why?

• Mg²⁺, because it has less electrons and greater repulsion between them
• Mg²⁺, because it has more protons and greater attraction for its electrons
• Na⁺, because it has less electrons and greater repulsion between them
• Na⁺, because it has more protons and greater attraction for its electrons

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Francium (Fr) has the lowest ionization energy in Group 1 because - 

• it has the smallest number of valence electrons
• it has the greatest atomic mass
• it has the greatest number of protons, so it attracts its electrons the strongest
• its 1 valence electron is very far from the nucleus, so little energy is needed to remove it

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Fluorine (F) has one of the highest ionization energies on the periodic table because - 

• it is a halogen and a gas
• it has seven valence electrons, and just needs one more electron to gain stability
• it is one of the largest atoms on the periodic table
• its electrons are close to and have a very strong attraction to the nucleus

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The element with the smallest ionization energy in Period 6 is - 

• Rn
• Cs
• Os
• Tm

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The element with the largest ionization energy of the following four is - 

• Tl
• In
• Al
• B

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