not reactive
All the synthetic elements on the Periodic Table appear after Uranium (atomic no. 92). These are the only synthetic elements.
Yes, all synthetic elements are man made.
Electronegativity is a measure of the reactivity; see the link below.
inertness, non-reactivity
Depends on the elements with which they are reacting with.
The capacity of elements to displace hydrogen can be determined based on their position in the reactivity series. Elements higher in the reactivity series can displace hydrogen from compounds of elements lower in the series. For example, metals like magnesium and zinc can displace hydrogen from water because they are higher in the reactivity series.
The reactivity is increasing goinng down in the group.
Synthetic or man-made elements. Obviously synthetic sounds significantly cooler.
Ununbium, also known as element 112, is a synthetic element with very limited information about its reactivity. However, being a member of group 12 in the periodic table, it is predicted to have similar reactivity to other elements in the same group, such as mercury and copernicium.
einsteinium,......
Carbon
Radioactive