You look at the properties of the elements around it and base your guess of off that.
the properties of a compound are not the same as the elements that form them.
Patterns in the elements’ properties. -Apex
I guess, the most fundamental is their valency. This dictates how many times it can bond to other elements. Elements with the same valency often share similar properties with other elements with the same valency. The Periodic Table is divided into 8 rows (and a D block). Each of these 8 rows have elements with similar properties, related to their valencies.
The properties of the compound will differ from the properties of the elements of which it is made.
The properties of the elements are changed.
he properties of salts are different from the properties of elements that go into making them
Elements in the same group have similar properties. The groups are made according to the properties of elements. Elements in a group have an equal number of valence electrons.
The properties of a compound are different from the properties of its individual elements. When elements combine to form compounds, the resulting compound can exhibit entirely new characteristics that are distinct from those of the individual elements.
what happens to the properties of elements when they react with each other element
These elements have similar chemical and physical properties.
It is helpful to organize things by characteristics because you can tell that certain elements are similar. For example if you knew nothing about the chemical or physical properties of (Rb) Rubidium, you could guess it has properties similar to (Cs) Cesium since they are in the same group. The common "Periodic Table" has many interesting forms. Search: "periodic table"
Mendeleev's periodic table allowed for the prediction of the properties of unknown elements by identifying gaps in the table where elements had not yet been discovered. By examining the properties of neighboring elements, Mendeleev was able to predict the properties of the missing elements and suggest their existence. His periodic table provided a framework for organizing elements based on their atomic mass and chemical properties, which allowed for the accurate prediction of the properties of undiscovered elements.