Answer:
Six C atoms (C₆); five H atoms (H₅); one N atom (N); no O atoms
Explanation:
The rule of 13 states that the formula of a compound is a multiple n of 13 (the molar mass of CH) plus a remainder r.
MF = CₙHₙ₊ᵣ
Y has a molecular mass of 91 u
91/13 =7r0
The formula can't be C₇H₇ because a hydrocarbon must have an even number of H atoms,
The odd mass and the odd number of H atoms make it reasonable to add an N atom and subtract CH₂ (CH₂ = 14):
C₇H₇ + N - CH₂ = C₆H₅N
Check:
6C = 6 × 12.000 = 72.000 u
5H = 5 × 1.008 = 5.040
1N = 1 × 14.003 = <u>14.003 </u>
TOTAL = 91.043 u
This is excellent agreement with the observed mass of 91.0425 u.
There are six C atoms (C₆)
There are five H atoms (H₅)
There is one N atom (N)
There are no O atoms.
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Explanation:
The charge of a helium atom is zero
It is neutral because
The number of unit negative charges = number of unit positive charges
One unit negative charge = -1.6 x 10^(-19) which is basically the charge of an electron
One unit positive charge = +1.6 x 10^(-19) which is basically the charge of a proton
A helium atom has 2 protons and 2 electrons, so it is neutral
NOTE: an alpha-particle (He2+) is a charged helium atom it has 2 protons and 0 electrons. Charge of an alpha particle = +3.2 x 10^(-19).
