If you look at the periodic table of elements, you can see that atomic number for phosphorus is 15. It means that it has 15 electrons and 15 protons total. Now you can write configuration for P which is: 1s22s22p63s23p3. or [Ne] 3s2<span> 3p</span><span>3 </span><span>
From here, you can see that it has 5 valence electrons (s2+p3).
In the periodic table of elements the number of protons+ number of neutrons is determined as atomic mass. Atomic mass of the P is 30.
number of neutrons = atomic mass-atomic number
number of neutrons = 30-15
number of neutrons= 15 </span>
We know the formula of the density:
ρ =
;
So the mass will be equal to:
m = ρ * V = 2.70 * 21.3 = 57,51 g =
57510 mg of substance.
So the answer is 57510.
C. marbles placed inside hollow sphere
Answer:
Explanation:
We're asked to calculate the number of atoms of
Ca
in
153
g Ca
.
What we must first do is convert the given mass of calcium to moles of calcium, using its molar mass (referring to a periodic table, this is
40.08
g
mol
):
153
g Ca
(
1
mol Ca
40.08
g Ca
)
=
3.82
mol Ca
Using Avogadro's number,
6.022
×
10
23
particles
mol
, we can calculate the number of atoms present:
3.82
mol Ca
(
6.022
×
10
23
atoms Ca
1
mol Ca
)
=
2.30
×
10
24
atoms Ca
