Electron affinity is the energy released when an electron is added to the gaseous atom or ion.
Electron affinity increases by moving from left to right in periodic table and decreases by moving from up to down.
So the correct answer is Te
Xe: being as noble gas it is unacceptable to gain an electron
The values of electron affinity for these elements:
Ba (13.9 kJ/mol) - Te (190.1 kJ/mol) - Xe (-80 kJ/mol) - Cs (45.5 kJ/mol)
> How many valence electrons does a helium atom have?
The electron configuration of Helium is simply 1s2. We see
that its outermost shell is the s shell and it contains 2 electrons, therefore
the number of valence electrons is also 2.
> What is the formula of the ion formed when potassium
achieves noble-gas electron configuration?
Potassium has a electron configuration of [Ar] 4s1. To
have an electron configuration of only [Ar] which is a noble gas, the one electron
from 4s1 should be removed, hence:
<span>K+</span>
Answer:
Metals at the top
nonmetals at the bottom
metalloids in the middle
Don't quote me, i could be wrong. i think this is the correct order.
Explanation:
Molality is a measure of concentration that relates the moles of solute to the kilograms of solvent, it is described by the following equation:
We are given the molality(2.50m) and kilograms of solvent(0.500kg), so we solve for moles of solute from the equation:
To make a 2.50molal NaOH solution would be needed 1.25moles of solute
Answer: 1.25 moles
