Answer:
oxygen
Explanation:
because the 2nd shell is not complete which is suppose to be 8 and since oxygen is 8 it first shell is 2 which is complete and the second shell which is 6 is not complete because we all know that 2+6=8 but the standard shell is
K-2
L-8
M-8
Potassium outermost electron occupy "4s" orbital
Frequency = speed of light/ wavelength of photon. wavelength = speed of light/frequency = 3 x 10^8 / 2.43 x 10^8= 1.23m
Answer:

Explanation:
The pH of a solution can be found by using the formula
![pH = - log [ {H}^{+} ]](https://tex.z-dn.net/?f=pH%20%3D%20-%20log%20%5B%20%7BH%7D%5E%7B%2B%7D%20%5D)
Since we are finding the H+ ions we find the antilog of the pH
So we have

We have the final answer as

Hope this helps you
Part 1)
Cu- <span>[Ar] 3d¹⁰4s¹ </span><span>atomic number: 29
</span>
<span>O- [He] 2s2 2p<span>4 atomic number:8
</span></span>La- <span>[Xe] 5d¹ 6s² </span><span>atomic number:57
Y- </span><span>[Kr] 4d¹5s² </span><span>atomic number:39
Ba- </span><span>[Xe] 6s² </span><span>atomic number:56
Tl- </span><span>[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p¹ </span><span>atomic number:81
Bi- </span> <span>[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p³ </span>atomic number:83
Part 2)
You are able to this by consulting the periodic table and following this steps:
-Find your atom's atomic number;
<span>-Determine the charge of the atom (these were all uncharged)
</span><span>-Memorize the order of orbitals (s, d, p, d.. and how many electrons they can fit)
</span>-<span>Fill in the orbitals according to the number of electrons in the atom
- </span><span>for long electron configurations, abbreviate with the noble gases</span>