Rank the following elements by atomic radius. Rank from largest to smallest atomic radius. To rank items as equivalent, overlap them. View Available Hint(s) Reset Help Mg P S Ar Al Smallest Largest From Largest to Smallest. No items in the box. Background Image Part B Rank the following atoms by number of valence electrons. Rank from most to fewest valence electrons. To rank items as equivalent, overlap them. View Available Hint(s) Reset Help In Xe I As K
The Correct Answer and Explanation is :
Part A: Ranking Elements by Atomic Radius
Atomic radius is a measure of the size of an atom, typically represented as the distance from the nucleus to the outermost electron. Several factors influence atomic radius:
- Period Trend: Atomic radius decreases across a period (from left to right) because as protons are added to the nucleus, the positive charge increases, pulling electrons closer to the nucleus.
- Group Trend: Atomic radius increases as you move down a group (top to bottom) because additional electron shells are added, increasing the distance between the nucleus and the outermost electrons.
Now, let’s rank the elements by atomic radius from largest to smallest:
- Mg (Magnesium) – It is in group 2 of the periodic table and has a relatively larger atomic radius due to fewer protons compared to elements in the same period.
- Al (Aluminum) – Aluminum is in group 13, so its atomic radius is slightly smaller than magnesium’s because it has more protons, pulling the electrons closer to the nucleus.
- P (Phosphorus) – Phosphorus is in group 15 and has an even smaller atomic radius than aluminum due to more protons.
- S (Sulfur) – Sulfur is in group 16, with a smaller atomic radius than phosphorus due to a higher number of protons.
- Ar (Argon) – Argon is a noble gas in group 18, and it has the smallest atomic radius. The higher nuclear charge in the same period pulls the electrons very close to the nucleus.
Ranking by atomic radius (largest to smallest):
- Mg > Al > P > S > Ar
Part B: Ranking Elements by Number of Valence Electrons
Valence electrons are the outermost electrons of an atom and are crucial in determining an element’s chemical properties and reactivity. Elements in the same group of the periodic table have the same number of valence electrons.
To rank the elements by their number of valence electrons from most to fewest:
- K (Potassium) – Potassium is in group 1, which means it has 1 valence electron.
- As (Arsenic) – Arsenic is in group 15 and has 5 valence electrons.
- I (Iodine) – Iodine is in group 17 and has 7 valence electrons.
- Xe (Xenon) – Xenon is in group 18, the noble gases, and has 8 valence electrons.
Ranking by number of valence electrons (most to fewest):
- Xe > I > As > K
Explanation:
- Atomic Radius (Part A):
- As you move down a group, the atomic radius increases because the electrons are farther from the nucleus. For example, magnesium has a larger radius than argon because magnesium is in a lower period and has fewer protons pulling the electrons inward.
- Across a period, atomic radius decreases because the number of protons increases, pulling electrons closer to the nucleus. Therefore, Argon, being a noble gas, has the smallest radius.
- Valence Electrons (Part B):
- Elements in the same group have the same number of valence electrons. Potassium (group 1) has 1, Arsenic (group 15) has 5, Iodine (group 17) has 7, and Xenon (group 18) has 8.
- This explains why xenon has the most valence electrons, while potassium has the fewest.