An element reacts with another element by sharing electrons. The elements keep sharing electrons until both elements have a full outer shell.
Chemical activity
Measure of its chemical reactivity.
For example halogens and sulfur reacts with silver.
Magnesium on heating reacts with oxygen and halogens but it also reacts with nitrogen.
New compounds can form through single replacement, double replacement, decomposition, synthesis, or combustion. Single replacement is where a compound reacts with an element and the element replaces one of the other elements within the compound. Double replacement is where a compound reacts with another compound and one element from each compound swaps places with the other element from the other compound to form brand new compounds. Synthesis is where two elements react with each other to form a compound. Decomposition is where a compound breaks into the elements that form it. Combustion is where oxygen combines with another compound to produce CO2 and H2O.
Ba looses its two electrons to form Ba 2+ ion and then it reacts with other elements to form compounds.
Potassium does not react at all with some elements such as helium, but when it reacts, it always forms a positive ion.
Any element in column 1 of a wide form periodic table has exactly one valence electron and reacts with other elements.
Chlorine reacts violently with a large number of elements.
Chemical activity
It barely reacts with other elements, just like gold. That is why it is considered a rare element.
Measure of its chemical reactivity.
Xenon reacts directly with fluorine only.
Alkaline earth metals
No, potassium is an extremely reactive metal that reacts very easily with other elements.
Chlorine
I reacts in order to get a filled valence shell of electrons.