Answer:
11 electrons total and 23amu
Explanation:
This tells us that sodium has 11 protons and because it is neutral it has 11 electrons. The mass number of an element tells us the number of protons AND neutrons in an atom (the two particles that have a measurable mass). Sodium has a mass number of 23amu.
Use a periodic table. Count the exponent for your atomic number. So, 1s2 2s2 2p5= Fluorine
1s2 2s2 2p6 3s2 3p5= Chlorine
1s2 2s2 2p6 3s2 3p6 4s2 3d6= Iron
Answer:
Yes
Explanation:
Masses for the three subatomic particles can be expressed in amu (atomic mass units) or grams. For simplicity, we will use the amu unit for the three subatomics. Both neutrons and protons are assigned as having masses of 1 amu each.
Fluorite is harder than gypsum but softer than apatite. Thus, the correct option is B.
<h3>What is the hardness of any element?</h3>
The hardness of any element may be defined as the capability of a material to oppose the process of deformation and remains in actual shape precisely.
According to the table of hardness scales by Mohs, the increasing order of given hardness of given elements is as follows:
Gypsum < Fluorite < Apatite.
Therefore, Fluorite is harder than gypsum but softer than apatite. Thus, the correct option is B.
To learn more about the Hardness of elements, refer to the link:
brainly.com/question/23721736
#SPJ1
To fully understand the problem, we use the ICE table to identify the concentration of the species. We calculate as follows:
Ka = 2.0 x 10^-9 = [H+][OBr-] / [HOBr]
HOBr = 0.50 M
KOBr = 0.30 M = OBr-
<span> HOBr + H2O <-> H+ + OBr- </span>
<span>I 0.50 - 0 0.30 </span>
<span>C -x x x
</span>---------------------------------------------
<span>E(0.50-x) x (0.30+x) </span>
<span>Assuming that the value of x is small as compared to 0.30 and 0.50 </span>
<span>Ka = 2.0 x 10^-9 = x (0.30) / 0.50) </span>
<span>x = 3.33 x 10^-9 = H+</span>
pH = 8.48
