Ions and Isotopes Practice Worksheet

Here is the step-by-step breakdown to solve the chemistry problems on the worksheet.

Part 1: Identify the total number of electrons

To find the number of electrons in an ion, you need to know the atomic number (number of protons) of the element and the charge of the ion.
* Atomic Number: Found on the periodic table. This equals the number of protons.
* Charge:
* A positive charge ($+$) means electrons were lost. Subtract the charge from the atomic number.
* A negative charge ($-$) means electrons were gained. Add the absolute value of the charge to the atomic number.

1. $\text{Al}^{+3}$: Aluminum (Al) is atomic number 13.
* $13 - 3 = 10$ electrons.
2. $\text{Fe}^{+3}$: Iron (Fe) is atomic number 26.
* $26 - 3 = 23$ electrons.
3. $\text{Mg}^{-2}$: Magnesium (Mg) is atomic number 12.
* $12 + 2 = 14$ electrons.
4. $\text{Sn}^{+2}$: Tin (Sn) is atomic number 50.
* $50 - 2 = 48$ electrons.
5. $\text{Co}^{-2}$: Cobalt (Co) is atomic number 27.
* $27 + 2 = 29$ electrons.
6. $\text{Co}^{-3}$: Cobalt (Co) is atomic number 27.
* $27 + 3 = 30$ electrons.
7. $\text{Li}^{+1}$: Lithium (Li) is atomic number 3.
* $3 - 1 = 2$ electrons.
8. $\text{Cr}^{+3}$: Chromium (Cr) is atomic number 24.
* $24 - 3 = 21$ electrons.
9. $\text{Rb}^{-1}$: Rubidium (Rb) is atomic number 37.
* $37 + 1 = 38$ electrons.
10. $\text{Pt}^{+2}$: Platinum (Pt) is atomic number 78.
* $78 - 2 = 76$ electrons.

Part 2: Indicate the total number of protons and electrons

* Protons: Always equal the atomic number (look at the element symbol).
* Electrons: Adjust the atomic number based on the charge (same rule as Part 1).

1. $\text{Co}^{+2}$: Cobalt is atomic number 27.
* Protons: 27
* Electrons: $27 - 2 = 25$
2. $\text{Co}^{+3}$: Cobalt is atomic number 27.
* Protons: 27
* Electrons: $27 - 3 = 24$
3. $\text{Cl}^{-1}$: Chlorine is atomic number 17.
* Protons: 17
* Electrons: $17 + 1 = 18$
4. $\text{K}^{+1}$: Potassium is atomic number 19.
* Protons: 19
* Electrons: $19 - 1 = 18$
5. $\text{S}^{-2}$: Sulfur is atomic number 16.
* Protons: 16
* Electrons: $16 + 2 = 18$
6. $\text{Sr}^{+2}$: Strontium is atomic number 38.
* Protons: 38
* Electrons: $38 - 2 = 36$
7. $\text{Al}^{+3}$: Aluminum is atomic number 13.
* Protons: 13
* Electrons: $13 - 3 = 10$
8. $\text{P}^{-3}$: Phosphorus is atomic number 15.
* Protons: 15
* Electrons: $15 + 3 = 18$

Part 3: Isotopes

The notation is written as: $\text{Element}^{\text{Mass Number}}$. The small number before the symbol (the subscript) is the atomic number.
The examples given are: ${}_{6}^{12}\text{C}$, ${}_{6}^{13}\text{C}$, ${}_{6}^{14}\text{C}$

a. The element is: Carbon (Symbol C).
b. The number 6 refers to the: Atomic Number (which is the number of protons).
c. The numbers 12, 13, and 14 refer to the: Mass Number (Protons + Neutrons).
d. First isotope (${}^{12}\text{C}$):
* Protons: 6 (from the atomic number).
* Neutrons: Mass Number - Protons = $12 - 6 = 6$.
e. Second isotope (${}^{13}\text{C}$):
* Protons: 6.
* Neutrons: $13 - 6 = 7$.
f. Third isotope (${}^{14}\text{C}$):
* Protons: 6.
* Neutrons: $14 - 6 = 8$.

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Final Answer:
1. Total number of electrons:
1. 10
2. 23
3. 14
4. 48
5. 29
6. 30
7. 2
8. 21
9. 38
10. 76

2. Table of Protons and Electrons:
* $\text{Co}^{+2}$: 27 Protons, 25 Electrons
* $\text{Co}^{+3}$: 27 Protons, 24 Electrons
* $\text{Cl}^{-1}$: 17 Protons, 18 Electrons
* $\text{K}^{+1}$: 19 Protons, 18 Electrons
* $\text{S}^{-2}$: 16 Protons, 18 Electrons
* $\text{Sr}^{+2}$: 38 Protons, 36 Electrons
* $\text{Al}^{+3}$: 13 Protons, 10 Electrons
* $\text{P}^{-3}$: 15 Protons, 18 Electrons

3. Isotopes:
a. Carbon
b. Atomic Number (or number of protons)
c. Mass Number
d. 6 protons and 6 neutrons
e. 6 protons and 7 neutrons
f. 6 protons and 8 neutrons