Fill-in-the-blank worksheet designed to help students master the fundamentals of atomic structure and subatomic particles.

To solve the problem and fill in the missing information in the provided diagram, let's break it down step by step. The diagram is about understanding the structure of an atom, specifically focusing on subatomic particles, electron shells, and atomic properties.

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1. Subatomic Particles

The table lists three subatomic particles with their charges, masses, and locations in the atom. Let’s identify them:

| Subatomic Particle | Charge | Mass | Location in Atom |
|--------------------|--------|------|------------------|
| Electron | -1 | ~0 | Outside the nucleus (in electron shells) |
| Proton | +1 | 1 | Nucleus |
| Neutron | 0 | 1 | Nucleus |

- Electron: Negatively charged, nearly massless, located outside the nucleus in electron shells.
- Proton: Positively charged, has a mass of 1 atomic mass unit (amu), located in the nucleus.
- Neutron: Neutral (no charge), has a mass of 1 amu, located in the nucleus.

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2. Electron Shells

The diagram shows electron shells around the nucleus. Each shell can hold a specific number of electrons:

| Atom Shell Number | Electrons It Can Hold |
|-------------------|-----------------------|
| 1 | 2 |
| 2 | 8 |
| 3 | 18 |

- Shell 1: Can hold up to 2 electrons.
- Shell 2: Can hold up to 8 electrons.
- Shell 3: Can hold up to 18 electrons.

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3. Finding the Number of Neutrons

To find the number of neutrons in an atom, you need:
- Atomic Mass (A): The total mass of the atom, which includes protons and neutrons.
- Atomic Number (Z): The number of protons in the nucleus.

The formula to calculate the number of neutrons is:
\[
\text{Number of Neutrons} = \text{Atomic Mass (A)} - \text{Atomic Number (Z)}
\]

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4. Analyzing Lithium (Li)

The diagram provides information about lithium (Li):
- Atomic Symbol: Li
- Atomic Number: 3
- Charge: -7 (This likely refers to the ionization state, but for now, we focus on the neutral atom.)

For a neutral lithium atom:
- Atomic Number (Z) = 3 (number of protons)
- Atomic Mass (A) ≈ 7 (approximately, based on the periodic table)

Using the formula:
\[
\text{Number of Neutrons} = \text{Atomic Mass (A)} - \text{Atomic Number (Z)} = 7 - 3 = 4
\]

So, lithium has:
- 3 protons
- 3 electrons
- 4 neutrons

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5. Filling in the Diagram

Now, let’s fill in the missing parts of the diagram:

#### Subatomic Particles Table
| Subatomic Particle | Charge | Mass | Location in Atom |
|--------------------|--------|------|------------------|
| Electron | -1 | ~0 | Outside the nucleus (in electron shells) |
| Proton | +1 | 1 | Nucleus |
| Neutron | 0 | 1 | Nucleus |

#### Electron Shells
| Atom Shell Number | Electrons It Can Hold |
|-------------------|-----------------------|
| 1 | 2 |
| 2 | 8 |
| 3 | 18 |

#### Finding Neutrons
"To find the number of neutrons in an atom, you need Atomic Mass (A) & Atomic Number (Z)."

#### Lithium Information
- Atomic Symbol: Li
- Atomic Number: 3
- Number of Neutrons: 4 (as calculated above)

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Final Answer

The completed diagram should look like this:

- Subatomic Particles Table:
- Electron: Charge = -1, Mass = ~0, Location = Outside the nucleus
- Proton: Charge = +1, Mass = 1, Location = Nucleus
- Neutron: Charge = 0, Mass = 1, Location = Nucleus

- Electron Shells:
- Shell 1: 2 electrons
- Shell 2: 8 electrons
- Shell 3: 18 electrons

- Finding Neutrons:
- Need Atomic Mass (A) & Atomic Number (Z)

- Lithium Information:
- Atomic Symbol: Li
- Atomic Number: 3
- Number of Neutrons: 4

Thus, the final boxed answer is:
\[
\boxed{4}
\]