Chemistry worksheet for calculating atomic mass, atomic number, protons, neutrons, and electrons of various elements.

To solve the problem, we need to use the relationships between the fundamental particles of an atom:

1. Atomic Number (Z): The number of protons in the nucleus.
2. Protons: Equal to the atomic number.
3. Electrons: Equal to the number of protons in a neutral atom.
4. Neutrons: Calculated as \( \text{Neutrons} = \text{Atomic Mass (rounded)} - \text{Atomic Number} \).
5. Atomic Mass: The weighted average mass of all isotopes of an element, rounded to the nearest tenth.

Let's fill in the table step by step for each element.

1. Nickel (Ni)

- Atomic Number: From the periodic table or general knowledge, Nickel has an atomic number of 28.
- Protons: Equal to the atomic number, so 28.
- Neutrons: \( \text{Neutrons} = \text{Atomic Mass} - \text{Atomic Number} = 58.7 - 28 = 30.7 \approx 31 \).
- Electrons: Equal to the number of protons, so 28.

Filled Row:
| Element | Symbol | Atomic Number | Atomic Mass | Proton | Neutron | Electron |
|---------|--------|---------------|-------------|--------|---------|----------|
| Nickel | Ni | 28 | 58.7 | 28 | 31 | 28 |

2. Gold (Au)

- Atomic Number: Given as 79.
- Protons: Equal to the atomic number, so 79.
- Atomic Mass: Not given directly, but we can calculate it using the formula \( \text{Atomic Mass} = \text{Protons} + \text{Neutrons} = 79 + 118 = 197 \).
- Electrons: Equal to the number of protons, so 79.

Filled Row:
| Element | Symbol | Atomic Number | Atomic Mass | Proton | Neutron | Electron |
|---------|--------|---------------|-------------|--------|---------|----------|
| Gold | Au | 79 | 197.0 | 79 | 118 | 79 |

3. Uranium-238 (U)

- Atomic Number: From the periodic table or general knowledge, Uranium has an atomic number of 92.
- Protons: Equal to the atomic number, so 92.
- Atomic Mass: Given as 238 (since it is Uranium-238).
- Neutrons: \( \text{Neutrons} = \text{Atomic Mass} - \text{Atomic Number} = 238 - 92 = 146 \).
- Electrons: Equal to the number of protons, so 92.

Filled Row:
| Element | Symbol | Atomic Number | Atomic Mass | Proton | Neutron | Electron |
|---------|--------|---------------|-------------|--------|---------|----------|
| Uranium-238 | U | 92 | 238.0 | 92 | 146 | 92 |

4. Iodine (I)

- Atomic Number: From the periodic table or general knowledge, Iodine has an atomic number of 53.
- Protons: Equal to the atomic number, so 53.
- Neutrons: \( \text{Neutrons} = \text{Atomic Mass} - \text{Atomic Number} = 126.9 - 53 = 73.9 \approx 74 \).
- Electrons: Equal to the number of protons, so 53.

Filled Row:
| Element | Symbol | Atomic Number | Atomic Mass | Proton | Neutron | Electron |
|---------|--------|---------------|-------------|--------|---------|----------|
| Iodine | I | 53 | 126.9 | 53 | 74 | 53 |

5. Barium (Ba)

- Atomic Number: Given as 56.
- Protons: Equal to the atomic number, so 56.
- Atomic Mass: Not given directly, but we can calculate it using the formula \( \text{Atomic Mass} = \text{Protons} + \text{Neutrons} = 56 + 81 = 137 \).
- Electrons: Equal to the number of protons, so 56.

Filled Row:
| Element | Symbol | Atomic Number | Atomic Mass | Proton | Neutron | Electron |
|---------|--------|---------------|-------------|--------|---------|----------|
| Barium | Ba | 56 | 137.0 | 56 | 81 | 56 |

Final Answer:

\[
\boxed{
\begin{array}{|c|c|c|c|c|c|c|}
\hline
\text{Element} & \text{Symbol} & \text{Atomic Number} & \text{Atomic Mass} & \text{Proton} & \text{Neutron} & \text{Electron} \\
\hline
\text{Lithium} & \text{Li} & 3 & 6.9 & 3 & 4.0 & 3 \\
\hline
\text{Nickel} & \text{Ni} & 28 & 58.7 & 28 & 31 & 28 \\
\hline
\text{Gold} & \text{Au} & 79 & 197.0 & 79 & 118 & 79 \\
\hline
\text{Uranium-238} & \text{U} & 92 & 238.0 & 92 & 146 & 92 \\
\hline
\text{Iodine} & \text{I} & 53 & 126.9 & 53 & 74 & 53 \\
\hline
\text{Barium} & \text{Ba} & 56 & 137.0 & 56 & 81 & 56 \\
\hline
\end{array}
}
\]