> 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>
<span>From the Born–Landé equation the lattice energy U ∝ (Z+ × Z-) / (r+ + r-) where Z+ and Z- are the charges on the cation and anion, respectively; r+ and r- are radii of the cation and anion, respectively.
The Z+×Z- term dominates. MgO has 2×2 (4) so it will have the higher U than Li2O Z+ × Z- = 2.
You only consider (r+ + r-) term when the Z+×Z- term is the same; smallest the (r+ + r-), the larger is the U.
U(MgO) = 3795 </span>kJ mol^-1
<span>U(Li2O) = 2799 kJ mol^-1
MgO has larger.
</span>
Answer: The U.S. has a greater gold resource
Explanation: Canada has 3,500 tons while the U.S. has 6,000
<span>The words you seek are soluble and insoluble.The chemical you want is an acid. Add an acid (acetic acid or hydrochloric acid) and the CaCO3 will fizz but CaCl2 will not</span>
Answer: -
Molarity is the term for the concentration expression that relates the moles of solute dissolved in each liter of solution.
Explanation: -
Molarity is defined as number of moles of solute dissolved per litre of the solution.
Molarity symbol is M.
1 M = 1 mol / L
Thus molarity is the term for the concentration expression that relates the moles of solute dissolved in each liter of solution
