Chlorine is an element and sodium chloride is a compound.

Answer

### Step-by-Step Text Solution:

1. **Definition of an Element**:
- An element is a pure substance that consists of only one type of atom. For example, chlorine (Cl) is an element because it is made up entirely of chlorine atoms.

2. **Characteristics of Elements**:
- Elements cannot be broken down into simpler substances by chemical means. They are the basic building blocks of matter.

3. **Definition of a Compound**:
- A compound is a substance formed when two or more different elements chemically combine in fixed proportions. Sodium chloride (NaCl) is an example of a compound.

4. **Composition of Sodium Chloride**:
- Sodium chloride is composed of two different elements: sodium (Na) and chlorine (Cl). When these two elements combine, they form the compound sodium chloride.

5. **Characteristics of Compounds**:
- Compounds have properties that are different from the individual elements that make them up. For instance, sodium is a highly reactive metal, and chlorine is a poisonous gas, but when they combine to form sodium chloride, they create a stable and edible substance (table salt).

6. **Conclusion**:
- In summary, chlorine is an element because it consists of only chlorine atoms, while sodium chloride is a compound because it is formed from the chemical combination of sodium and chlorine atoms.