Objective Chemistry (2 questions)

[ritwik06]

Homework Statement

1. Why is the atomic size of 0 group elements more than that of the rest of the elements in that period?
2. Which is th element with least electron affinity?

Homework Equations

None

The Attempt at a Solution

1. Force of repulsion between the electrons is what my teacher tell me.
2. A noble gas or francium?

Help!

 

[ShawnD]

1. Why is the atomic size of 0 group elements more than that of the rest of the elements in that period?
1. Force of repulsion between the electrons is what my teacher tell me.

Which group is 0? My table has 1-18 across and 1-7 down. I've never seen a table that starts at 0.

Two main things affect size - electronegativity and overall number of electrons. Fluorine is very small because of its high electronegativity and low number of electrons; it can tightly hold electrons close to the nucleus. Potassium is big because of its low electronegativity; electrons stay far from the nucleus and can be easily pulled away by things like fluorine or oxygen. Radon is big because it has 86 electrons.

2. A noble gas or francium?

Francium.

 

[Gokul43201]

Group 18 (noble gases) is sometimes referred to as group 0.

I've not actually seen a periodic table with this format. Does Group 0 actually get arranged to the left of group 1? In the more common version of the priodic table, group 18 elements have the smallest (not largest) atomic radii of all elements in a given period. But if you pushed that group to the left side and promoted every element to the next period, then the converse would be true.