How reliable are the properties of group 1 and their compounds to predict their position in the periodic table?
Analyses extent to which properties of elements and their compounds may be predicted by knowing the position of the elements in the periodic table.
For group 1, they are fairly reliable. Group 1 is also called the alkaline metals. This is the group that starts with hydrogen, then lithium, sodium, potassium, rubidium, cesium, and francium. They all have one lone electron in their outer energy orbital, and predictably will donate that lone electron to satisfy the octet rule of electron orbitals. With the exception of hydrogen, and possibly lithium, they have to be isolated with a hydrocarbon immersion so as to separate them from the water vapor in Earths atmosphere, otherwise they react violently to produce strong bases. Starting with sodium, there is increasing violent chemical activity when combined with water. I watched a video recently where a sample of rubidum was dropped into a bathtub full of water, then a sample of cesium. The rubidium blew a hole in the side of the tub, and the cesium annihilated the entire tub! I shudder to think what a sample of francium would do. So the predictability factor for group 1 is fairly accurate, increasing virulence as you descend into the group.