Free Printable Atomic Structure Worksheets - Free Printable

Atomic Structure Worksheet Solution and Explanation

#### 1. Using the periodic table, write the name of the element next to each atom.

The images provided show electron configurations for different atoms. Let's analyze them:

- First Atom:
- The nucleus has 2 protons (indicated by the black dots in the center).
- There are 2 electrons orbiting the nucleus.
- This corresponds to Helium (He), which has an atomic number of 2.

- Second Atom:
- The nucleus has 8 protons.
- There are 8 electrons orbiting the nucleus.
- This corresponds to Oxygen (O), which has an atomic number of 8.

- Third Atom:
- The nucleus has 17 protons.
- There are 17 electrons orbiting the nucleus.
- This corresponds to Chlorine (Cl), which has an atomic number of 17.

Answers:
- First Atom: Helium (He)
- Second Atom: Oxygen (O)
- Third Atom: Chlorine (Cl)

---

#### 2. Draw the following atoms.

We need to draw the electron configurations for Hydrogen, Boron, and Helium.

- Hydrogen (H):
- Atomic number = 1
- 1 proton in the nucleus
- 1 electron in the first shell (1s orbital)

Drawing:
```
[●] // Nucleus with 1 proton
● // 1 electron in the 1s orbital
```

- Boron (B):
- Atomic number = 5
- 5 protons in the nucleus
- Electron configuration: 1s² 2s² 2p¹
- 2 electrons in the 1s orbital
- 2 electrons in the 2s orbital
- 1 electron in the 2p orbital

Drawing:
```
[●●●●●] // Nucleus with 5 protons
● // 1s orbital (2 electrons)
● // 2s orbital (2 electrons)
● // 2p orbital (1 electron)
```

- Helium (He):
- Atomic number = 2
- 2 protons in the nucleus
- Electron configuration: 1s²
- 2 electrons in the 1s orbital

Drawing:
```
[●●] // Nucleus with 2 protons
●● // 1s orbital (2 electrons)
```

---

#### 3. Fill in the blanks.

The diagram shows an oxygen atom with its atomic number, symbol, and atomic mass. We need to fill in the blanks and answer the questions.

- Oxygen (O):
- Atomic number = 8
- Symbol = O
- Atomic mass ≈ 15.999

Diagram:
```
8
┌───┐
│ O │
└───┘
15.999
```

What parts of an atom does the atomic number represent?
- The atomic number represents the number of protons and number of electrons in a neutral atom.

How do you figure the number of neutrons?
- The number of neutrons is calculated using the formula:
\[
\text{Number of neutrons} = \text{Atomic mass (rounded to the nearest whole number)} - \text{Atomic number}
\]

---

#### 4. Fill in the blanks for Carbon (C) and Potassium (K).

We need to determine the number of protons, electrons, and neutrons for Carbon and Potassium.

- Carbon (C):
- Atomic number = 6
- Atomic mass ≈ 12.003
- Number of protons = Atomic number = 6
- Number of electrons = Atomic number = 6
- Number of neutrons = Atomic mass (rounded to 12) - Atomic number = 12 - 6 = 6

- Potassium (K):
- Atomic number = 19
- Atomic mass ≈ 39.098
- Number of protons = Atomic number = 19
- Number of electrons = Atomic number = 19
- Number of neutrons = Atomic mass (rounded to 39) - Atomic number = 39 - 19 = 20

Answers:
- Carbon (C):
- Number of protons = 6
- Number of electrons = 6
- Number of neutrons = 6

- Potassium (K):
- Number of protons = 19
- Number of electrons = 19
- Number of neutrons = 20

---

Final Answer:

\boxed{
\begin{aligned}
&\text{1. Helium (He), Oxygen (O), Chlorine (Cl)} \\
&\text{2. Drawings as explained above} \\
&\text{3. Atomic number represents protons and electrons. Neutrons = Atomic mass - Atomic number} \\
&\text{4. Carbon: Protons = 6, Electrons = 6, Neutrons = 6; Potassium: Protons = 19, Electrons = 19, Neutrons = 20}
\end{aligned}
}