Question

1. draw the bohr model for na⁺
2. draw the bohr model for ca²⁺
3. draw the bohr model for sr²⁺

Explanation:

Problem 2: Draw the Bohr model for $\boldsymbol{\ce{Na+}}$

Step 1: Determine the number of protons, neutrons, and electrons in $\ce{Na+}$

• Protons (P): The atomic number of sodium (Na) is 11, so the number of protons in $\ce{Na+}$ is 11 (since the atomic number equals the number of protons and is not changed by the formation of an ion).
• Neutrons (N): The most common isotope of sodium is $\ce{^{23}Na}$, so the number of neutrons is calculated as the mass number minus the atomic number: $23 - 11 = 12$.
• Electrons (e⁻): A neutral sodium atom has 11 electrons. Since $\ce{Na+}$ is a cation with a +1 charge, it has lost 1 electron. So the number of electrons is $11 - 1 = 10$.

Step 2: Determine the electron shell configuration

• The electron shell configuration follows the rules of electron filling: the first shell (n=1) can hold a maximum of 2 electrons, the second shell (n=2) can hold a maximum of 8 electrons, and the third shell (n=3) can hold a maximum of 18 electrons (but for sodium, we only need to consider up to the second shell for $\ce{Na+}$).
• For $\ce{Na+}$ with 10 electrons:
• The first shell (n=1) will have 2 electrons.
• The second shell (n=2) will have the remaining $10 - 2 = 8$ electrons.

Step 3: Draw the Bohr model

• Nucleus: Draw a small circle in the center to represent the nucleus. Inside the nucleus, write "P: 11" and "N: 12" to indicate the number of protons and neutrons, respectively.
• Electron shells: Draw two concentric circles around the nucleus to represent the electron shells.
• On the first shell (closer to the nucleus), place 2 dots (or small circles) to represent the 2 electrons in the first shell.
• On the second shell (further from the nucleus), place 8 dots to represent the 8 electrons in the second shell.

Problem 3: Draw the Bohr model for $\boldsymbol{\ce{Ca^{2+}}}$

Step 1: Determine the number of protons, neutrons, and electrons in $\ce{Ca^{2+}}$

• Protons (P): The atomic number of calcium (Ca) is 20, so the number of protons in $\ce{Ca^{2+}}$ is 20.
• Neutrons (N): The most common isotope of calcium is $\ce{^{40}Ca}$, so the number of neutrons is $40 - 20 = 20$.
• Electrons (e⁻): A neutral calcium atom has 20 electrons. Since $\ce{Ca^{2+}}$ is a cation with a +2 charge, it has lost 2 electrons. So the number of electrons is $20 - 2 = 18$.

Step 2: Determine the electron shell configuration

• The electron shell configuration:
• The first shell (n=1) holds 2 electrons.
• The second shell (n=2) holds 8 electrons.
• The third shell (n=3) holds 8 electrons (since $2 + 8 + 8 = 18$ for the 18 electrons in $\ce{Ca^{2+}}$).

Step 3: Draw the Bohr model

• Nucleus: Draw a small circle in the center. Inside, write "P: 20" and "N: 20".
• Electron shells: Draw three concentric circles around the nucleus.
• First shell: 2 electrons.
• Second shell: 8 electrons.
• Third shell: 8 electrons.

Problem 4: Draw the Bohr model for $\boldsymbol{\ce{Sr^{2+}}}$

Step 1: Determine the number of protons, neutrons, and electrons in $\ce{Sr^{2+}}$

• Protons (P): The atomic number of strontium (Sr) is 38, so the number of protons in $\ce{Sr^{2+}}$ is 38.
• Neutrons (N): The most common isotope of strontium is $\ce{^{88}Sr}$, so the number of neutrons is $88 - 38 = 50$.
• Electrons (e⁻): A neutral strontium atom has 38 electrons. Since $\ce{Sr^{2+}}$ is a cation with a +2 charge, it has lost 2 electrons. So the number of electrons is $38 - 2 = 36$.

Step 2: Determine the electron shell configuration

• The electron shell configuration follows the Aufbau principle:
• First shell (n=1): 2 electrons.
• Second shell (n=2): 8 electrons.
• Third shell (n=3): 18 electrons.
• Fourth shell (n=4): 8 electrons (since $2 + 8 + 18 + 8 = 36$ for the 36 electrons in $\ce{Sr^{2+}}$).

Step 3: Draw the Bohr model

• Nucleus: Draw a small circle in the center. Inside, write "P: 38" and "N: 50".
• Electron shells: Draw four concentric circles around the nucleus.
• First shell: 2 electrons.
• Second shell: 8 electrons.
• Third shell: 18 electrons.
• Fourth shell: 8 electrons.

Final Answers (Descriptions of the Drawn Models)

• For $\ce{Na+}$: Nucleus with P=11, N=12; two electron shells with 2 electrons in the first shell and 8 electrons in the second shell.
• For $\ce{Ca^{2+}}$: Nucleus with P=20, N=20; three electron shells with 2, 8, and 8 electrons respectively.
• For $\ce{Sr^{2+}}$: Nucleus with P=38, N=50; four electron shells with 2, 8, 18, and 8 electrons respectively.

Answer:

Step 1: Determine the number of protons, neutrons, and electrons in $\ce{Sr^{2+}}$

• Protons (P): The atomic number of strontium (Sr) is 38, so the number of protons in $\ce{Sr^{2+}}$ is 38.
• Neutrons (N): The most common isotope of strontium is $\ce{^{88}Sr}$, so the number of neutrons is $88 - 38 = 50$.
• Electrons (e⁻): A neutral strontium atom has 38 electrons. Since $\ce{Sr^{2+}}$ is a cation with a +2 charge, it has lost 2 electrons. So the number of electrons is $38 - 2 = 36$.

Step 2: Determine the electron shell configuration

• The electron shell configuration follows the Aufbau principle:
• First shell (n=1): 2 electrons.
• Second shell (n=2): 8 electrons.
• Third shell (n=3): 18 electrons.
• Fourth shell (n=4): 8 electrons (since $2 + 8 + 18 + 8 = 36$ for the 36 electrons in $\ce{Sr^{2+}}$).

Step 3: Draw the Bohr model

• Nucleus: Draw a small circle in the center. Inside, write "P: 38" and "N: 50".
• Electron shells: Draw four concentric circles around the nucleus.
• First shell: 2 electrons.
• Second shell: 8 electrons.
• Third shell: 18 electrons.
• Fourth shell: 8 electrons.

Final Answers (Descriptions of the Drawn Models)

• For $\ce{Na+}$: Nucleus with P=11, N=12; two electron shells with 2 electrons in the first shell and 8 electrons in the second shell.
• For $\ce{Ca^{2+}}$: Nucleus with P=20, N=20; three electron shells with 2, 8, and 8 electrons respectively.
• For $\ce{Sr^{2+}}$: Nucleus with P=38, N=50; four electron shells with 2, 8, 18, and 8 electrons respectively.