Answer: determines the age of sample Carbon-14 is used in radiocarbon dating and radiolabeling. Medically important, a radioactive isotope is carbon-14, which is used in a breath test to determine the ulcer-causing bacteria Heliobacter pylori
The radiocarbon age of a certain sample of unknown age can be determined by measuring its carbon 14 content and comparing the result to the carbon-14 activity in modern and background samples.
Absorbance values greater than or equal to 1.0 are too high. If you are getting absorbance values of 1.0 or above, your solution is too concentrated. Simply dilute your sample and recollect data . Keep in mind that absorbance is the logarithm of the transmission (T) of light through a sample
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Answer: D) It has two more electrons than protons.
Explanation: Sulphur (S) is an element with atomic number 16 and thus contains 16 electrons. A neutral atom contains equal number of protons and electrons.
![S:16:[Ne]3s^23p^4](https://tex.z-dn.net/?f=S%3A16%3A%5BNe%5D3s%5E23p%5E4)
An atom on losing electrons gains positive charge and on gaining electrons gain negative charge.
Sulphide ion
is formed by gaining 2 electrons to attain stable configuration of argon and thus contains two more electrons than protons.
![S^{2-}:18:[Ne]3s^23p^6:[Ar]](https://tex.z-dn.net/?f=S%5E%7B2-%7D%3A18%3A%5BNe%5D3s%5E23p%5E6%3A%5BAr%5D)
Answer: SiCl₄(s) + 4 H₂O(l) → H₄SiO₄(aq) + 4 HCl(aq)
Explanation:
You can pretend there is an imaginary line splitting the chemical equation into two on the arrow to help balance the equation.
Balance out chlorine on both sides, add the coefficient 4 to HCl
now there are 4 chlorines on the left and the right side.
Then, balance out Hydrogen on both sides, add the coefficient 4 to H₂O
now, there are 4*2=8 hydrogens on the left and 4+4=8 hydrogens on the right.
Counting the total number of atoms on both sides of the arrow, the equation is balanced
1 Si = 1 Si
4 Cl = 4 Cl
4 O = 4 O
8 H = 8 H
Dalton postulated that atoms of the same elements had the same mass while atoms of different elements had different masses.
The discovery of isotopes revealed that atoms of the same element did not necessarily have same masses, they could have different masses.
Therefore, the modern periodic table that we use nowadays contains the average atomic mass of all the isotopes found for a given element.