How Many Protons Does Calcium Ion Have?

This blog will answer the question of how many protons a calcium ion has. It will also cover in-depth what calcium is, how many protons and electrons it has, the role calcium plays in the human body, and some frequently asked questions about the same topic.

How Many Protons Does Calcium Ion Have?

Ca2+  represents that a calcium ion has 20 protons and 18 electrons. The 2+ charge in the superscript indicates that there is a loss of two electrons, i.e. 2-2 = 18. As indicated, when atoms form ions, they either lose or gain electrons. 

When there is no change in the number of protons and neutrons, it is known as a nucleus, which remains intact. When there is a loss of electrons, it produces a positively charged ion, also known as a cation. When there is a gain of electrons, it produces a negatively charged ion, also known as an anion. 

What are protons, electrons, and neutrons?

Let’s recap some of the basics. Atoms are the smallest units in which matter can be divided, without any release of electrically charged particles. In a way, an atom is considered to be the basic building block in chemistry. An atom is also considered to be the smallest unit of matter that consists of its chemical characteristics or elements.

In the centre of the atom are protons and neutrons which make up the nucleus. Electrons surround this nucleus. Protons are known to have a positive charge, whereas electrons have a negative charge. The power of the charge in protons and electrons is the same in size, but they are the opposite. Neurons have no charge, they are neither positive nor negative. Protons and electrons attract each other, as opposite charges tend to attract. 

What is the role of Calcium in the Human Body?

Calcium Cation, also known as an ion, is the metabolically-active portion of calcium and is not bound to proteins. It is known to be circulating in the blood. In the human body, calcium cation has the role of human metabolite and is a cofactor.

In the body, calcium ions are mediated into cytoplasm and organelles through calcium channels. These calcium ions are heavily involved in the regulation of biological functions of the body including muscle contractions, heart contractions, the transmission of neural messages, memory as well as learning (Berridge et al., 2000).

Calcium ions are also involved in the formation and development of embryos, cell division as well as differentiation. It metabolises cell energy and is involved in the expression and regulation of genes. If there are abnormalities in the calcium channels,  it causes dysregulation in calcium homeostasis and can result in diseases (Berridge et al., 2000).

Research has found the role of calcium ions in the regulation of vascular functioning in the human body (Liu et al., 2019). Calcium is considered to be one of the body’s electrolytes amongst others known as sodium, magnesium, etc. electrolytes are minerals which carry an electric charge the moment they are dissolved in the blood, or other body fluids. However, it is interesting that most of the body’s calcium is not charged.

Most of the body’s calcium is said to be stored in the bones (99% of it). However, muscle cells as well as the bloodstream also contain calcium. Calcium, in the human body, is essential for the following: 

  • Forming of bone and teeth
  • Successful muscle contraction
  • Ensuring normal functioning of enzymes
  • Reducing blood clotting
  • Maintaining normal heart rhythm

The body is in precise control of the amount of calcium in the cells and blood. It moves calcium out of bones into the bloodstream whenever required, to maintain the steadiness of calcium in the blood. Hence, when people do not consume enough calcium, the body mobilises too much calcium from the bones into the blood, which results in the weakening of the bones. Thus, people need to consume around 1,000 to 1,500 mcg of calcium a day.

Calcium in the blood is regulated by the parathyroid hormone and calcitonin. 

Four parathyroid glands which are located around the thyroid gland in the neck produce the parathyroid hormone. When there is a decrease in the calcium level in the blood, the parathyroid glands start producing more parathyroid hormone and vice versa. The functions of the parathyroid hormone are:

  • It leads to the kidneys to excrete less calcium in the urine
  • It causes the digestive tract to absorb more calcium
  • It also leads to the kidneys activating vitamin D which then enables the digestive tract to absorb more calcium.

Calcitonin is produced in the human body by the cells of the thyroid gland. The function of calcitonin is to lower (only slightly) the calcium level in the blood by slowing the breakdown of bones. 

When there is too little calcium in the blood, a condition known as hypocalcemia is diagnosed. Whereas, in the case of too much calcium in the blood, hypercalcemia is diagnosed.


In conclusion, Calcium Ion has 20 protons. Since it has 18 electrons, it is referred to as Ca+2. 

Frequently Asked Questions: How many Protons Does Calcium Ion Have?

What is calcium?

Calcium is a chemical element. It is one of the alkaline-earth metals in group 2 of the periodic table. Calcium is an abundant metallic element found in the human body as well as the earth’s crust. The compounds of calcium are widely distributed.

What are the particles involved in making up an atom?

Protons, neutrons, and electrons make up an atom.

What is a calcium ion called?

The calcium ion is called Ca2+. This means it has more protons than electrons, specifically two fewer electrons. This means the calcium ion is not stable. Calcium is a pure element is a grey metal. 

How do you write calcium?

Calcium is represented as ‘Ca’.

How does Calcium become balanced?

Ca2+ indicates that calcium has a positive charge of 2. This means, calcium can accept 2 more electrons. After this, calcium will be balanced, or have zero charges.

What is an ion?

An ion is referred to as a charged atom or molecule. Ions are charged because the number of electrons and protons it has are not in equal numbers. 

Are all atoms ions?

In essence, ions are atoms or molecules that have either gained or lost one or more of their electrons. Hence, they either have a net positive or negative charge. A consensus is that all atoms can be ions, but not all ions are atoms. 

Are electrolytes ions?

Yes, electrolytes are an example of ions. These include chloride, calcium, potassium, magnesium, and sodium ions which are essential to health. 

Out of protons, electrons, and neutrons, what is in the centre of the atom?

In an atom, protons and neutrons are in the centre. However, hydrogen is the only atom that has no neutrons usually. The nucleus of hydrogen atoms is made up of just 1 proton. One or even two neutrons are observed in only about a small percentage of hydrogen atoms. When atoms of the same element have different numbers of neutrons, they are referred to as isotopes.

Can you eat pure calcium?

Eating pure calcium is not a good idea. Even though the body needs a good amount of calcium, eating raw metal is not the way to go forward with it. Pure calcium reacts strongly and negatively with water and hence can be detrimental to the human tongue and oesophagus. 

Are all atoms of the same size?

Yes, all atoms are usually the same size, irrespective of whether they have 3 or 90 electrons. 50 million atoms of any solid matter when lined up in a row would be around 1 cm or 0.4 inches in measure. 


Berridge, M. J., Lipp, P., and Bootman, M. D. (2000). The Versatility and Universality of Calcium Signalling. Nat. Rev. Mol. Cel. Biol. 1 (1), 11–21. doi:10.1038/35036035

Liu L, Guo M, Lv X, Wang Z, Yang J, Li Y, Yu F, Wen X, Feng L and Zhou T (2021) Role of Transient Receptor Potential Vanilloid 4 in Vascular Function. Front. Mol. Biosci. 8:677661. DOI: 10.3389/fmolb.2021.677661

Piste, Pravina & Sayaji, Didwagh & Avinash, Mokashi. (2012). Calcium and its Role in Human Body. Int J Res Pharm Biomed Sci. 4. 2229-3701. 

Zhang P, Zhang C-B, Chen Z and Liu X-Y (2022) Editorial: The Role of Calcium Channels in Human Health and Disease. Front. Mol. Biosci. 9:834108. DOI: 10.3389/fmolb.2022.834108