specify ions, cations and anions predict the fee of an anion or cationbased ~ above the ar of the aspect in the routine table

In simple tasiilaq.netical reactions, the nucleus of each atom stays unchanged. Electrons, however, can be included to atoms by transfer type other atoms, shed by transport to various other atoms, or mutual with other atoms. The transfer and sharing the electrons amongst atoms administer the tasiilaq.netistry the the elements. Throughout the development of some compounds, atoms obtain or shed electrons, and type electrically fee particles called ions(Figure (PageIndex1); video clip (PageIndex1))


Figure (PageIndex1): (a) A salt atom (Na) has equal number of protons and also electrons (11) and is uncharged. (b) A salt cation (Na+) has actually lost an electron, therefore it has actually one an ext proton (11) than electrons (10), offering it an all at once positive charge, signified through a superscripted to add sign.

You are watching: Predict the charge of a beryllium ion

One have the right to use the regular table come predict even if it is an atom will form an anion or a cation, and also you can often predict the fee of the result ion. Atom of plenty of main-group metals lose sufficient electrons to leaving them through the same variety of electrons as an atom of the coming before noble gas. Come illustrate, an atom of one alkali metal (group 1) loses one electron and forms a cation v a 1+ charge; an alkaline planet metal (group 2) loses two electrons and also forms a cation with a 2+ charge, and also so on. For example, a neutral calcium atom, with 20 protons and 20 electrons, conveniently loses two electrons. This results in a cation v 20 protons, 18 electrons, and a 2+ charge. It has the same variety of electrons as atoms of the coming before noble gas, argon, and is symbolized Ca2+. The name of a metal ion is the very same as the name of the steel atom indigenous which it forms, for this reason Ca2+ is referred to as a calcium ion.

When atoms of nonmetal elements type ions, they normally gain enough electrons to offer them the same number of electrons as an atom of the next noble gas in the routine table. Atom of group 17 acquire one electron and form anions v a 1− charge; atom of group 16 obtain two electrons and kind ions v a 2− charge, and also so on. Because that example, the neutral bromine atom, v 35 protons and also 35 electrons, can gain one electron to provide it through 36 electrons. This outcomes in an anion through 35 protons, 36 electrons, and a 1− charge. It has actually the same number of electrons together atoms the the next noble gas, krypton, and also is symbolized Br−. (A discussion of the theory sustaining the favored standing of noble gas electron number reflected in this predictive rules because that ion formation is detailed in a later on chapter of this text.)

Note the usefulness that the periodic table in predicting likely ion formation and charge (Figure (PageIndex2)). Relocating from the far left to the best on the periodic table, main-group aspects tend to form cations through a charge equal to the group number. That is, team 1 elements type 1+ ions; team 2 elements kind 2+ ions, and also so on. Moving from the far right to the left top top the routine table, elements often type anions through a an unfavorable charge same to the number of groups relocated left native the noble gases. Because that example, group 17 aspects (one group left of the noble gases) type 1− ions; group 16 facets (two teams left) kind 2− ions, and so on. This trend have the right to be offered as a guide in countless cases, yet its predictive value decreases when relocating toward the center of the regular table. In fact, change metals and also some various other metals often exhibit variable charges that room not predictable by their location in the table. Because that example, copper can kind ions with a 1+ or 2+ charge, and also iron can type ions through a 2+ or 3+ charge.


Figure (PageIndex2): Some facets exhibit a constant pattern of ionic charge as soon as they form ions.

Example (PageIndex2): formation of Ions

Magnesium and nitrogen reaction to kind an ionic compound. Predict which forms an anion, which forms a cation, and the dues of every ion. Create the symbol for each ion and name them.


Magnesium’s place in the regular table (group 2) tells us that the is a metal. Metals type positive ion (cations). A magnesium atom must shed two electrons to have the same number electrons together an atom of the previous noble gas, neon. Thus, a magnesium atom will form a cation with two under electrons than protons and a charge of 2+. The symbol because that the ion is Mg2+, and it is dubbed a magnesium ion.

See more: What Type Of Plate Boundary Could Form A Mountain Chain Of Sedimentary Rock? ?

Nitrogen’s place in the periodic table (group 15) reveals that it is a nonmetal. Nonmetals form negative ions (anions). A nitrogen atom must gain three electron to have the same variety of electrons as an atom that the following noble gas, neon. Thus, a nitrogen atom will type an anion with three an ext electrons than protons and also a charge of 3−. The symbol for the ion is N3−, and it is called a nitride ion.