Final answer:
The element not required for a valid contract is equal consideration between parties, although consideration must be present. All other options listed are essential elements of a valid contract.
Step-by-step explanation:
The requirement that is NOT a part of a contract is that equal consideration is required between the involved parties. While it is true that for a contract to be valid, consideration must be present, it does not necessarily have to be equal. The other listed elements, including competent parties, a legal purpose, and offer and acceptance, are all essential components of a valid contract.
Competency ensures that all parties have the legal capacity to enter into a contract. A contract's legal purpose ensures its content adheres to the law, while offer and acceptance establish mutual assent to the contract terms. Societal economic growth relies on the security provided by a legal system to enforce such contracts, which instills confidence in individuals or firms to use their property, trade, or sell it effectively.