Atomic Radius and Isoelectronic Series

Melanie Fine presents a chemistry question about which ion or atom has the largest radius. She discusses the strontium ion, rubidium ion, Krypton atom, bromide ion, and selenide ion, explaining that they form an isoelectronic series with 36 electrons each. The video explains that the smallest atom has the most protons due to stronger nuclear charge, which attracts electrons more closely. The selenide ion, having the fewest protons, has the largest radius. The video concludes with an invitation to join an online chemistry community for more resources.

Which of the following ions or atoms is being compared to determine the largest atomic radius?

• Hydrogen ion, Helium atom, Lithium ion, Beryllium ion

• Sodium ion, Magnesium ion, Aluminum ion, Silicon atom

• Strontium ion, Rubidium ion, Krypton atom, Bromide ion, Selenide ion

• Carbon atom, Nitrogen ion, Oxygen ion, Fluoride ion

What is an isoelectronic series?

• A set of compounds with identical molecular structures

• A series of elements with similar atomic masses

• A group of ions and atoms with the same number of electrons

• A group of atoms with the same number of protons

How many electrons does the Krypton atom have in the isoelectronic series discussed?

• 37 electrons

• 34 electrons

• 36 electrons

• 35 electrons

What happens to the atomic size when the nuclear charge increases?

• The atomic size fluctuates

• The atomic size decreases

• The atomic size remains the same

• The atomic size increases

Which element or ion has the smallest atomic radius in the given series?

• Strontium ion

• Selenide ion

• Bromide ion

• Rubidium ion

Why does the element with the most protons have the smallest atomic radius?

• Because it has a larger atomic mass

• Because it has more electrons

• Because the nuclear charge is stronger, pulling electrons closer

• Because it is located higher on the periodic table

Which ion in the series has the largest atomic radius?

• Rubidium ion

• Bromide ion

• Strontium ion

• Selenide ion

What is the relationship between protons and electrons in determining atomic size?

• Protons have no effect on electrons

• Protons attract electrons, decreasing atomic size

• Protons and electrons both increase atomic size

• Protons repel electrons, increasing atomic size

What is the main factor that determines the size of an atom in an isoelectronic series?

• The number of electrons

• The number of neutrons

• The atomic mass

• The number of protons

Where can students find more chemistry videos and practice problems?

• At the local library

• On social media platforms

• In their chemistry textbook

• On the chem.com website