# Help with the following questions???

## 1) What is the net charge of an atom with no electrons? 2) What is the mass number of a nitrogen atom with $8$ neutrons? 3) What is the net charge of a nitrogen atom with only $6$ electrons? 4) What is the mass number of a chlorine atom with $18$ neutrons? 5) What is the atomic number of a nitrogen-15 isotope? 6) What is the element with atomic number $17$? 7) What is the name of element $X$? 8) What is the net charge of a nitrogen atom with $8$ electrons?

##### 1 Answer
Sep 10, 2016
1. Protons are known to be positively-charged particles. Therefore, an atom with only protons can only be positively charged.
2. The mass number is the total number of protons plus neutrons. Therefore, the mass number must be $7 + 8 = \boldsymbol{15}$.
3. The net charge only incorporates charged particles, so with $7$ protons (positive) and $6$ electrons (negative), the net charge is simply $7 \times \left(+\right) + 6 \times \left(-\right) = \boldsymbol{+ 1}$.
4. Same idea as $2$. Therefore, the mass number is $17 + 18 = 35$. We write that as ""^35 X, where $X$ is the chemical symbol.
5. See $2$.
6. The element is identified by its atomic number, which is its number of protons. Therefore, with $17$ protons we have $\boldsymbol{\text{Cl}}$, or chlorine. Look at any periodic table to convince yourself that the $17$th element is $\text{Cl}$.
7. This question doesn't make sense. The element always has a name, if it's a previously-discovered element. Otherwise it's called the latin for "unknown element number $X$"...
8. $\boldsymbol{- 1}$. See $3$.