Forming ionic compounds
Shiny element that is a good conductor of electricity and heat, and which forms basic oxides.The smallest part of an element that can exist. have only a few Subatomic particle, with a negative charge and a negligible mass relative to protons and neutrons. in their outer shell whereas Element that is a poor conductor of electricity and heat, and which forms acidic oxides. atoms have lots of electrons in their outer shell. This means that metals tend to react with non-metals. When a metal reacts with a non-metal, electrons transfer from the metal to the non-metal. This creates oppositely charged Electrically charged particle, formed when an atom or molecule gains or loses electrons.:
- metal atoms lose electrons to form positive ions (An atom or group of atoms that have lost electrons and become positively charged. Most cations are formed from metals.)
- non-metal atoms gain electrons to form negative ions (An atom or group of atoms that have gained electrons and become negatively charged. Most anions are formed from non-metals.)
The strong A force of attraction between particles with opposite charges. of attraction between the oppositely charged ions hold them together. A small separate A collection of two or more atoms held together by chemical bonds. like water only contains three atoms. However, an An ionic compound occurs when a negative ion (an atom that has gained an electron) joins with a positive ion (an atom that has lost an electron). contains millions of ions, arranged in a regular 3D pattern. This arrangement is called a The structure of ionic compounds formed from millions of oppositely charged ions in a 3 dimensional arrangement..
Dot and cross diagrams
A dot and cross diagram models the transfer of electrons from metal atoms to non-metal atoms. The electrons from one atom are shown as dots, and the electrons from the other atom are shown as crosses.
Example - sodium chloride
When sodium reacts with chlorine, one electron is transferred from the sodium atom to the chlorine atom. This creates a positive sodium ion and a negative chloride ion.
For every sodium ion in sodium chloride there is one chloride ion.
Ionic compounds have no overall charge. The atoms must react in the correct ratio. This is shown in the dot and cross diagram.
Example - sodium oxide
When sodium reacts with oxygen the oxide has a charge of -2. Each sodium ion has a charge of +1.
The slideshow shows dot and cross diagrams for the ions in sodium chloride, magnesium oxide and calcium chloride.
Image caption, 1. Ionic bonding in sodium chloride
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