When was the ion formed

Compounds formed from positive and negative ions are called ionic compounds. Individual atoms can gain or lose electrons. When they do, they become monatomic ions. When atoms gain or lose electrons, they usually gain or lose a characteristic number of electrons and so take on a characteristic overall charge. Table 3. There are several things to notice about the ions in Table 3. First, each element that forms cations is a metal, except for one hydrogen , while each element that forms anions is a nonmetal.

This is actually one of the chemical properties of metals and nonmetals: metals tend to form cations, while nonmetals tend to form anions. Second, most atoms form ions of a single characteristic charge.

Thus, if you commit the information in Table 3. A few elements, all metals, can form more than one possible charge. Unfortunately, there is little understanding which two charges a metal atom may take, so it is best to just memorize the possible charges a particular element can have. Note the convention for indicating an ion. The magnitude of the charge is listed as a right superscript next to the symbol of the element.

An element symbol without a charge written next to it is assumed to be the uncharged atom. Naming an ion is straightforward. If the element has more than one possible charge, the value of the charge comes after the element name and before the word ion. In print, we use roman numerals in parentheses to represent the charge on the ion, so these two iron ions would be represented as the iron II cation and the iron III cation, respectively.

For a monatomic anion, use the stem of the element name and append the suffix -ide to it, and then add ion.

This is similar to how we named molecular compounds. Chemical formulas for ionic compounds are called ionic formulas. A proper ionic formula has a cation and an anion in it; an ionic compound is never formed between two cations only or two anions only.

The key to writing proper ionic formulas is simple: the total positive charge must balance the total negative charge. Because the charges on the ions are characteristic, sometimes we have to have more than one of a cation or an anion to balance the overall positive and negative charges.

It is conventional to use the lowest ratio of ions that are needed to balance the charges. Each ion has a single charge, one positive and one negative, so we need only one ion of each to balance the overall charge. When writing the ionic formula, we follow two additional conventions: 1 write the formula for the cation first and the formula for the anion next, but 2 do not write the charges on the ions.

The formula Na 2 Cl 2 also has balanced charges, but the convention is to use the lowest ratio of ions, which would be one of each. By convention, the formula is MgO.

To balance the charges with the lowest number of ions possible, we need to have two chloride ions to balance the charge on the one magnesium ion.

Rather than write the formula MgClCl, we combine the two chloride ions and write it with a 2 subscript: MgCl 2. What is the formula MgCl 2 telling us?

There are two chloride ions in the formula. Although chlorine as an element is a diatomic molecule, Cl 2 , elemental chlorine is not part of this ionic compound. The water contains excessive amounts of cations such as iron and calcium. Ions are charged substances that have formed through the gain or loss of electrons.

Cations form from the loss of electrons and have a positive charge while anions form through the gain of electrons and have a negative charge. Cations are the positive ions formed by the loss of one or more electrons. The most commonly formed cations of the representative elements are those that involve the loss of all of the valence electrons.

The electron arrangement of the sodium ion is now the same as that of the noble gas neon. Consider a similar process with magnesium and aluminum.

For representative elements under typical conditions, three electrons is usually the maximum number that will be los.

Representative elements will not lose electrons beyond their valence because they would have to "break" the octet of the previous energy level which provides stability to the ion. Anions are the negative ions formed from the gain of one or more electrons. When nonmetal atoms gain elections, they often do so until their outermost principal energy level achieves an octet.

For fluorine, which has an electron arrangement of 2, 7 , it only needs to gain one electron to have the same electron arrangement as neon.

Forming an octet eight electrons in the outer shell provides stability to the atom. The electron arrangement of the fluoride ion 2, 8 will also change to reflect the gain of an electron. Under typical conditions, three electrons is the maximum that will be gained in the formation of anions. Since ions form from the gain or loss of electrons, we can also look at the number of subatomic particles protons, neutrons, and electrons found in an ion.

Therefore, sodium tends to lose an electron to become more stable. On the other hand, chlorine tends to gain an electron to become Cl —. Chlorine naturally has 17 electrons but it would be more stable with 18 electrons 2 in its inner most shell, 8 in its second shell, and 8 in its valence shell.

Therefore, chlorine will take an electron from another atom to become negatively charged. Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:. Skip to main content. Atoms, Molecules, and Ions.

Search for:. Ions form when atoms lose or gain electrons to obtain a full outer shell:. Metal atoms lose electrons from their outer shell when they form ions:.

For elements in groups 1, 2 and 3, the number of electrons lost is the same as the group number. The outer shells of non-metal atoms gain electrons when they form ions:.