Yes, an earnest money deposit is required when you purchase a property. It does not have to be submitted though until you have an accepted offer. It just depends how it is written on the contract. A Realtor can advise you as to how much to put down.
Not sure what property you are inquiring, however most property purchases do require a deposit when making an offer. The amount may differ from property to property and what type of property it is. A buyer agents should be able to guide you with what you need,.