Periodic Trends Atomic Radius

How do scientists measure the size of atoms?

• by counting energy levels

• measuring the distance between 2 nuclei

• measuring the nucleus

• using the atomic number

The atom with the largest atomic radius in Group 18 is - 

• Ar

• He

• Kr

• Rn

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

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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Of the halogens, which has the smallest radius?

• F

• Br

• He

• At

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The Periodic Table of the Elements is useful for revealing patterns and trends in the elements. Which statement accurately describes a pattern in the size of atomic radii in the Periodic Table of the Elements?

• Atomic radii decrease from left to right across a period and decrease from top to bottom in a group.

• Atomic radii increase from left to right across a period and increase from top to bottom in a group.

• Atomic radii decrease from left to right across a period and increase from top to bottom in a group.

• Atomic radii increase from left to right across a period and decrease from top to bottom in a group.

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Which of these elements has the greatest atomic radius? 

• H

• N

• Cl

• Cs

Which atom has the largest atomic radius?

• potassium

• rubidium 

• francium

• cesium

Select the element with the largest atomic radius

• Potassium

• Scandium

• Gallium

• Arsenic

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Which of the following elements has the largest atomic radius in Period 3?

• A) Sodium (Na)

• B) Magnesium (Mg)

• C) Silicon (Si)

• D) Chlorine (Cl)

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