Pure sodium is a highly reactive element. When placed in water, sodium will actually explode, producing flames and concussive forces.
Because their outermost energy level is only partially filled, some elements are highly reactive, I believe.
Synthetic elements can be highly reactive due to their unstable nature and tendency to decay into more stable forms through radioactive decay or by forming compounds with other elements. Some synthetic elements have very short half-lives, making them extremely reactive in the short time they exist.
The highly reactive non-metals are in the halogen group. They just need one more electron to fill the octet. Therefore they are highly reactive. For example fluorine and chlorine. And the highly reactive metals are placed in the first group (alkali metals). For example Sodium and potassium.
Highly reactive elements can be kept from reacting by holding them in containers that are made of elements that are very unreactive (or at least not reactive to the highly reactive elements they contain). Unfortunately, the 6 known stable inert elements exist at room temperature only in gas form, so do not make good containers; however, some substances such as glass are very resilient and their molecular structures tend to be stable and unreactive (which is why glass is a common material for beakers and other containers to hold a wide -- but not unlimited -- variety of chemicals).
Chlorine and fluorine, with fluorine more reactive. Some would also include oxygen. (The two remaining halogens are not gaseous at room temperature.)
Potassium is highly reactive, even explosive in some circumstances.
Yes sodium is very reactive metal.Just because of this it is kept in kerosene or some another oil because it is very reactive with oxygen and water.
The group 18 elements are the noble gases, which are extremely inert. Some of them, heavier than argon, do form highly reactive compounds principally with fluorine.
To keep highly reactive elements from reacting, they are often stored in inert gases such as argon or mineral oil. This helps prevent them from coming into contact with oxygen or water, which could lead to unwanted chemical reactions. Storage in a controlled environment can help maintain the stability of these elements.
There are many reactive elements. They show up more on the upper left of the Periodic Table. Some of these are plutonium, uranium, Mercury and lead.
Not all elements with one valence electron are highly combustible, but some are. Elements like lithium (Li) and potassium (K) with one valence electron can be highly reactive and flammable. However, elements like helium (He) and neon (Ne) with one valence electron are inert and not combustible.
Fluorine is highly reactive and corrosive, which can easily react with many materials, including metals. Teflon is a highly inert and non-reactive material, making it suitable for storing and handling fluorine safely without reacting with the container.