Group 6 elements usually have extra electrons to make give them an octet. So, they have 6 electrons to start and when they have an octet, they have 8.
We can find the charge by doing simple math 6 - 8 = -2
Answer is D)
Answer:
0.29 moles of PbCl₂
Explanation:
Given data:
Mass of lithium chloride = 24.3 g
Moles of PbCl₂ = ?
Solution:
Chemical equation;
PbSO₄ + 2LiCl → PbCl₂ + Li₂SO₄
Number of moles of LiCl:
Number of moles = mass/ molar mass
Number of moles = 24.3 g/ 42.394 g/mol
Number of moles = 0.57 mol
Now we will compare the moles of PbCl₂ with LiCl .
LiCl : PbCl₂
2 : 1
0.57 : 1/2×0.57 = 0.29 mol
Answer:
2.94
Explanation:
There is some info missing. I think this is the original question.
<em>A solution is prepared at 25 °C that is initially 0.38 M in chloroacetic acid (HCH₂ClCO₂), a weak acid with Ka= 1.3 x 10⁻³, and 0.44 M in sodium chloroacetate (NaCH₂CICO₂). Calculate the pH of the solution. Round your answer to 2 decimal places.</em>
<em />
We have a buffer system formed by a weak acid (HCH₂ClCO₂) and its conjugate base (CH₂CICO₂⁻ coming from NaCH₂CICO₂). We can calculate the pH using the Henderson-Hasselbalch equation.
pH = pKa + log [CH₂CICO₂⁻]/[HCH₂ClCO₂]
pH = -log 1.3 x 10⁻³ + log (0.44 M/0.38 M)
pH = 2.94
Answer:
B. PROTONS EXHIBIT STRONGER PULL ON OUTER f ORBITALS
Explanation:
Lanthanide contraction is the greater than normal decrease in the ionic radius of the lanthanide series from atomic number 57 to atomic number 71. This decrease is rather not expected of the ionic radii of these elements and they result in the greater decrease in the subsequent series of the lanthanides from the atomic number 72. The cause of which is as a result of the poor shielding effects of the nuclear charge around the electrons of the f orbitals. So therefore, protons are strongly pulled out of the 4f orbital and as a result of the poor shielding effect which causes the electrons of the 6s orbitals to be drawn more closer to the nucleus and hence resulting in a smaller atomic radii. It is worthy to note that the shielding effects of the inner electrons decreasing from s orbital to the f orbital; that is s > p > d > f. So from the decrease in the shielding effects from s to the f orbitals, lanthanide contraction results from the inability of the orbitals far away from s like the 4f orbiatls to shield the outermost shells of the lanthanide elements. So the cause of lanthanide contraction is the action of the protons which strongly pull the electrons of the f orbitals because of the poor shielding effects due to the distance of this orbital from the nucleus.
