- Using the choices below, which is the complete symbol for the isotope that has the following subatomic particles: 19 protons, 21 neutrons, and 18 electrons.
C.
D.
E.
A.
40 -1
B.
40
21
iR-1
33K+1 4.K+1
izArt1
b. B
A
d. D
e. E
с
c.
a.

The elements in nature have several types of isotopes

Isotopes are atoms whose no-atom has the same number of protons while still having a different number of neutrons.

So Isotopes are elements that have the same Atomic Number (Proton)

The element has : 19 protons, 21 neutrons, and 18 electrons.

atomic mass = protons+neutrons = 19+21=40

atomic number=number of protons=19

charge of elements = protons-electrons = 19-18=+1

The element in the periodic system having the atomic number 19 is K

So symbol of element

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !