Is it true that the tricuspid valve is between the right atrium and ventricle, whereas the semilunar valve is between the left atrium and the ventricle?
The first part is correct. The tricuspid valve is between the right atrium and ventricle. However, the bicuspid (mitral) valve is found between the left atrium and ventricle.
The semilunar valve is in fact found in between both the pulmonary artery and right ventricle, as well as the aorta and left ventricle. The semilunar valves are essentially found where the blood is leaving the heart.