Question

questions (use a periodic table):

1. write the isotope notation for an atom with 7 protons and 7 neutrons.
2. write the isotope of the atom that has 14 protons and a mass of 28.
3. write the isotope of the atom that has 19 protons and 20 neutrons.
4. what atom has 92 electrons?
5. u - 238 has ______ more neutrons than u - 235.
6. all carbon isotopes have ____ protons.
7. c - 12 and c - 14 are isotopes. what is another isotope of carbon?
8. how many neutrons are in cl - 36?
9. what is the mass of au - 197?
10. which 2 subatomic particles make up the mass of an atom?

Explanation:

Step1: Recall isotope notation rules

Isotope notation is $_{Z}^{A}X$, where $Z$ is the atomic number (number of protons) and $A$ is the mass - number (sum of protons and neutrons), and $X$ is the chemical symbol.

Step2: Answer question 1

An atom with 7 protons is nitrogen (N). Mass number $A=7 + 7=14$. Isotope notation is $_{7}^{14}N$.

Step3: Answer question 2

An atom with 14 protons is silicon (Si). Given mass number $A = 28$, isotope notation is $_{14}^{28}Si$.

Step4: Answer question 3

An atom with 19 protons is potassium (K). Mass number $A=19 + 20=39$. Isotope notation is $_{19}^{39}K$.

Step5: Answer question 4

In a neutral atom, number of electrons = number of protons. An atom with 92 protons is uranium (U).

Step6: Answer question 5

For U - 238, mass number $A = 238$, atomic number of U $Z = 92$, number of neutrons $n_1=238 - 92=146$. For U - 235, mass number $A = 235$, number of neutrons $n_2=235 - 92=143$. Difference is $146-143 = 3$.

Step7: Answer question 6

All carbon isotopes have 6 protons (atomic number of carbon is 6).

Step8: Answer question 7

Another isotope of carbon is C - 13.

Step9: Answer question 8

For Cl - 36, atomic number of Cl $Z = 17$, mass number $A = 36$. Number of neutrons $n=36 - 17=19$.

Step10: Answer question 9

The mass of Au - 197 is 197 (mass - number is given in the isotope notation).

Step11: Answer question 10

Protons and neutrons make up the mass of an atom.

Answer:

1. $_{7}^{14}N$
2. $_{14}^{28}Si$
3. $_{19}^{39}K$
4. Uranium (U)
5. 3
6. 6
7. C - 13
8. 19
9. 197
10. Protons, Neutrons