Is Calcium Flammable? (A comprehensive guide)

In this, article we will answer the following question: “Is Calcium Flammable?”, as well as other important matters about different calcium compounds.

Is Calcium Flammable?

As you probably expect, it depends. There are many calcium compounds, some are flammable, and others are not. But even when it does burn, the combustion reaction is very different from the usual burning of fuels.

What is calcium?

Calcium is a simple chemical element.

It is an alkaline earth metal that presents many forms.

Calcium is the fifth most abundant element in Earth’s crust and the third most common metal.

Pure calcium can hardly be found naturally. Normally it needs to be isolated. Its properties are very different from other calcium compounds.

The ion Calcium can be found in many foods, it’s harmless and is an important part of our diet. Without it, our bones would get weak and break.

Calcium Carbonate is the most common calcium compound found naturally. There also exists calcium oxide (quicklime). They’re both extensively used in the construction industry as an ingredient of concrete.

Other important types of Calcium are carbide, hydroxide, chloride, hypochlorite, sulfate, and calcium phosphate.

Basic Chemistry

Before explaining important points about Calcium, we first need to provide some basic information about Chemistry. 

We promise it won’t be too long or nerdy.

Chemistry is one of the major fields of Science. It is the scientific study of the properties and behaviors of matter.

In Chemistry, a “chemical” is literally anything in the universe that can be studied from the point of view of particles. Anything that exists in this world and has weight is made of atoms.


Atom is the smallest particle that forms a chemical element.

If we could zoom in on a piece of anything (yourself, a chair, water, the sun, a fridge, etc.), at some point we would encounter the smaller particle possible.

In fact, there are smaller particles but they are not important right now. And they are not ordinary.

The size of a typical atom is around 100 picometers (0,0000000001 meters). Even in science, we normally admit that atoms have a ball-like shape, so you can surely imagine them like little balls.

An atom is composed of basically 3 things: protons, neutrons, and electrons.

Every atom has a nucleus, a tiny spot in the middle of a ball that’s already very small. It contains almost all of the atom’s mass. Protons and neutrons are very firmly bonded together. They are the nucleus. 

These two fellas are not going to stay apart, no matter what we do to them, no matter how sharp your knife is. Unless you have a particle accelerator, a nuclear energy plant, or a banana (yes, they have a low level of nuclear radiation. But they’re totally safe).

Circulating around an atom we have the electrons, and this is where chemistry starts. Every chemical reaction happens with the electrons, only.

It’s important to say that atoms are species that are not ionized (didn’t lose or received other electrons). But having a neutral charge is not a synonym for stability, unlike common sense may make us think. 

All atoms of the known Universe are written in the periodic table.

The Periodic Table

We hope the last topic wasn’t too long or boring. We promise this will be quick.

The periodic table is simply a graphic arrangement of all the atoms in the known Universe, according to their characteristics. It is human-made.

There are four colors on it, it separates the atoms in specific overall properties. The red-pink block is made of alkali and alkaline earth metals, where our beloved Calcium (Ca) is placed.

The more you get down on the table, the heavier the atoms get.


You can see that there is a number on every atom. This is their proton numbers, the total amount of protons each has. This is the most important atom signature.

For example, the Calcium atom has 20 protons. If we had quantum tweezers (this ain’t a real thing) that work on a picoscopic scale (far smaller than the microscopic) and took one proton out, we would no longer be staring at a Calcium atom but at a Potassium (K) atom.

The Calcium atom

Calcium is a very ductile silvery metal. It has two electrons willing to join chemical bondings.

A very small piece of it could create a big fire if in contact with water.

This is the most interesting thing about alkaline earth metals, they burn in contact with water, instead of oxygen gas.

But the thing is, it’s still reacting with oxygen like happens in most burnings. Calcium is so crazy for giving away its two electrons (to oxide) that once it jumps into water (H2O), it breaks the water molecules.

Every atom of Calcium takes away one atom of Oxygen and one of Hydrogen (a hydroxide, OH). The remaining hydrogens have no choice but to bond with themselves, creating hydrogen gas. Its flammability will be assessed later.

Calcium is much more stable when it gives away its two electrons, hence why it’s found that way in nature.

Calcium compounds and flammability

When in water or aqueous means, calcium is in an ionic form (Ca+2). Pure calcium tends to be very reactive and interacts violently with water and other common compounds, so it’s very dangerous.

The calcium ion, although, doesn’t present any harm to humans and is mandatory in our diet. It also can’t ignite.

Pure calcium

Calcium (Ca) is a heavy alkaline earth metal. It can’t really get ignited, but the oxidation it promotes is highly energetic, as we will see.

When Ca comes in contact with air or oxygen, nothing happens. If we try to burn it, nothing happens (it will only melt when reaches about 800ºC).

So how does it catch fire?

The answer is: it doesn’t actually catch fire, not if we use the common meaning of the word. And it will only happen if in water.

But it does suffer oxidation, which is basically what combustion is. But instead of using a fuel source that generates carbon dioxide and water, it will generate Ca(OH)2 (calcium hydroxide) and hydrogen gas.

This reaction with water generates a lot of energy. This energy will help the hydrogen gas to react with the oxygen that’s already in the air, producing even more heat. You can see a video about it here.

We also can’t touch metallic Calcium (pure calcium) with our bare hands. The moisture naturally present in our hands can react with the substance and cause severe injuries.

Calcium oxide 

Calcium oxide (CaO), quicklime, or burnt lime is made by calcinating calcium carbonate. It’s used widely in the construction industry, especially in the formation of concrete.

This compound can’t burn, but it can still react with water and give rise to a lot of heat.

It’s a substance that can generate a lot of heat if in contact with water. If CaO is mixed with water and then bottled, the bottle will explode.

Since no flames rise from this chemical reaction, is not considered flammable but it’s hazardous.

See more about it here.

Calcium carbide

Also named Calcium acetylide. The molecule is made with one atom of Calcium for two of Carbon.

Formula: CaC2.

Is mainly used to produce acetylene, calcium cyanamide, and fertilizers.

It is used in carbide lamps.

The compound is considered highly flammable, having the highest flammability hazard according to the NFPA 704 (the fire diamond diagram).

You can find more specific information about it here.

Calcium hydroxide

Calcium hydroxide is a byproduct of the combustion reaction between pure calcium and water.

It’s already an oxidized compound, so there’s no risk of flammability involved in using it, and it won’t burn.

It’s a very corrosive substance. The biggest danger is if it gets in contact with the eyes or skin.

For more specific information, visit this site.

Calcium chloride 

It’s a type of salt. Has the formula CaCl2

It’s not a flammable substance but could give off toxic fumes or gases if in a fire.

You can check more specifics about it here.

Calcium hypochlorite

It’s used as a sanitizer and on water treatments, overall. 

Has the formula Ca(OCl)2.

It’s a very oxidizing, corrosive, and irritant substance that can be very harmful to humans and the environment but is not flammable.

Check out more about it here.

Calcium sulfate

Calcium sulfate (CaSO4) that’s used for many things, including: in the creation of building materials, as a desiccant, in medicine, and dentistry as an impression material.

It’s a product that can be irritating if inhaled but the effect is not acute. 

It’s not a flammable substance and it can’t burn.

See more about it here.

Calcium phosphate

Calcium phosphate is a family of materials and minerals that contains calcium ions together with (but are not limited to) phosphate anions.

It is present in foods and is used in the production of phosphoric acid, and fertilizers.

It also plays a very important role in our metabolism, and 99% of our skeleton is in the form of calcium phosphate salts.

Calcium phosphate compounds are not flammable, but some could be irritating.


Calcium can be flammable, it only depends on which form of calcium are we talking about. Pure calcium is very flammable and explosive, Calcium carbide is very flammable as well, and calcium oxide is not flammable but could unleash a lot of heat if in water. 

Calcium in the following forms is not flammable: hydroxide, chloride, hypochlorite, sulfate, and phosphate.

Many of these forms are strong oxidizers that could cause us harm. Some also generate toxic fumes upon heating, and others are irritating to the touch.

Frequently Asked Questions (FAQS): Is Calcium Flammable?

Is calcium in water bad for you?

No. The calcium in water is actually the ion Calcium, which we require in our diet. Calcium in water might be good for you.

Is calcium a mineral?

Yes. Calcium is much more commonly found as a mineral in nature. It’s also a mineral required in our diet. It’s not considered a vitamin because vitamins are organic, and this one is an inorganic compound.

Is quicklime dangerous?

Yes. If in contact with water, it could unleash a lot of heat, This heat could be enough to ignite fuel materials that are close by, and could also harm you directly. Never leave quicklime (calcium oxide) and water under pressure. 


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