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Thus, anions (negatively charged ions) are larger than the parent molecule or atom, as the excess electron(s) repel each other and add to the physical size of the ion, because its size is determined by its electron cloud. Cations are smaller than the corresponding parent atom or molecule due to the smaller size of the electron cloud.
Relative radii of atoms and ions. The neutral atoms are colored gray, cations red, and anions blue. Ions may be larger or smaller than the neutral atom, depending on the ion's electric charge. When an atom loses an electron to form a cation, the other electrons are more attracted to the nucleus, and the radius of the ion gets smaller.
The hydrogen anion, with its loosely held two-electron cloud, has a larger radius than the neutral atom, which in turn is much larger than the bare proton of the cation. Hydrogen forms the only cation that has no electrons, but even cations that (unlike hydrogen) still retain one or more electrons are still smaller than the neutral atoms or ...
In the simplest case, the cation is a metal atom and the anion is a nonmetal atom, but these ions can be more complex, e.g. molecular ions like NH + 4 or SO 2− 4. In simpler words, an ionic bond results from the transfer of electrons from a metal to a non-metal to obtain a full valence shell for both atoms.
Cations are positively (+) charged ions while anions are negatively (−) charged. This can be remembered with the help of the following mnemonics. Cats have paws ⇔ Cations are pawsitive. [27] Ca+ion: The letter t in cation looks like a + (plus) sign. [28] An anion is a negative ion. (An egative ion ⇒ Anion). [29]
If an atom has more electrons than protons, then it has an overall negative charge and is called a negative ion (or anion). Conversely, if it has more protons than electrons, it has a positive charge and is called a positive ion (or cation). The electrons of an atom are attracted to the protons in an atomic nucleus by the electromagnetic force.
Ionic compounds containing hydrogen ions (H +) are classified as acids, and those containing electropositive cations [57] and basic anions ions hydroxide (OH −) or oxide (O 2−) are classified as bases. Other ionic compounds are known as salts and can be formed by acid–base reactions. [58]
The hydrogen anion, H −, is a negative ion of hydrogen, that is, a hydrogen atom that has captured an extra electron. The hydrogen anion is an important constituent of the atmosphere of stars, such as the Sun. In chemistry, this ion is called hydride. The ion has two electrons bound by the electromagnetic force to a nucleus containing one proton.