If you sent the BTC to a valid but unowned address, the BTC would go there and be lost. … If you tried to send bitcoins to an invalid address, your transaction will not be valid and will not be processed by the network. Hence no bitcoin will have moved. All syntax-valid Bitcoin addresses exist already.
How often do Bitcoin addresses change?
We automatically generate a new address for you after every transaction you make or when funds are moved between your wallet and our storage system. This is done to protect your privacy, so that a third-party cannot view all other transactions associated with your account simply by using a blockchain explorer.