Highly unreactive elements that will not chemically combine include:
Platinum (Pt)
Gold (Au)
Helium (He)
Argon (Ar)
Krypton (Xe)
Neon (Ne)
The first two are unreactive because they are at the bottom of the metals reactivity series. The rest are unreactive because they are part of the inert gases.
Second answer: Platinum and gold do react, but sparingly. Helium is the only one of the inert gases that has been shown never to react. The others form compounds (admittedly quite unstable ones).
Argon is a noble gas and is typically unreactive due to its stable electronic configuration. It does not readily react with other elements at normal conditions.
Helium is inert and does not readily react with other elements, including fluorine. Fluorine is a highly reactive element and will readily react with many other elements, but not with helium due to its stable electron configuration.
Silicon is a non-metal element that is not very reactive. It usually forms covalent bonds rather than ionic bonds with other elements. It reacts with oxygen at high temperatures to form silicon dioxide, but it does not readily react with most other elements at room temperature.
Group 1 and Group 2 elements are highly reactive and easily lose electrons to form stable compounds with other elements. This reactivity makes them unlikely to exist freely in nature. They quickly react with other elements to achieve a stable electron configuration.
Noble gases, group 18 on the periodic table, do not react readily with other elements due to their stable and full outer electron shells. This leads to low reactivity and makes them chemically inert.