Final answer:
In decreasing atomic radius, the order of the elements is Americium, Uranium, Strontium, Potassium, Gold, Rhodium, Bromine, Sulfur, Neon, and Carbon. The atomic radius increases down a group and decreases across a period, and changes in electron count can affect the radius due to electron-electron repulsion and effective nuclear charge.
Step-by-step explanation:
The question asks to order a set of elements in terms of decreasing atomic radius. Atomic radius generally increases as you move down a group in the periodic table and decreases as you move from left to right across a period. To illustrate, within the same group, strontium (Sr) will have a larger atomic radius than calcium (Ca), because Sr is located further down in the group. Similarly, calcium will have a larger atomic radius than silicon (Si), as Si is further to the right of Ca in the same period. The atomic radius will then increase for elements positioned further to the left and down the periodic table.
Considering this trend, the order of the given elements by decreasing atomic radius would be:
- Americium (f)
- Uranium (a)
- Strontium (c)
- Potassium (j)
- Gold (e)
- Rhodium (g)
- Bromine (b)
- Sulfur (h)
- Neon (d)
- Carbon (i)
To explain the effect on atomic radius when gaining an electron, as electrons are added to the same shell, the electron-electron repulsion increases, making the atom larger. Conversely, losing an electron generally decreases the atomic radius because of reduced electron-electron repulsion and increased effective nuclear charge pulling the remaining electrons closer.