Key Difference – Ionic vs Covalent Compounds
Many differences can be noted between ionic and covalent compounds based on their macroscopic properties such as solubility in water,电导率,melting points and boiling points。这些差异的主要原因是它们的粘结模式的差异。因此，他们bonding patterncan be deemed as thekey difference betweenionic and covalent compounds.(Difference Between Ionic and Covalent Bonds) When ionic bonds are formed, electron(s) is donated by a metal and donated electron(s) is accepted by a non-metal. They form a strong bond due to the electrostatic attraction. Covalent bonds are formed between two non-metals. In covalent bonding, two or more atoms shareelectrons满足八位准规则。通常，离子键比共价键强。这导致其物理特性的差异。
What are Ionic Compounds?
Ionic bonds are formed when two atoms have a large difference in theirelectronegativityvalues. In the process of bond formation, the less electronegative atom losses electron(s) and more electronegative atom gains those electron(s). Therefore, resulting species are oppositely charged ions and they form a bond due to the strong electrostatic attraction.
Ionic bonds are formed betweenmetals and non-metals。In general, metals do not have manyvalence electronsin the outermost shell; however, non-metals have closer to eight electrons in the valence shell. Therefore, non-metals tend to accept electrons to satisfy the octet rule.
Example of ionic compoundis Na++ Cl–ànacl
Sodium(metal) has only one valence electron and Chlorine (non-metal) has seven valence electrons.
What are Covalent Compounds?
通过在两个或多个原子之间共享电子以满足“八位核规则”来形成共价化合物。这种键合类型通常在非金属化合物，相同化合物的原子或附近元素的原子中发现。两个原子具有几乎相同的电负性值不会从其价值外壳交换（捐赠 /接收）电子。相反，他们共享电子以实现八位配置。
共价化合物的示例are Methane (CH4), Carbon monoxide (CO), Iodine monobromide (IBr)
共价Bonding
What is the difference between Ionic and Covalent Compounds?
离子化合物和共价化合物的定义
Ionic compound:离子化合物的化合物cations and anionswhich are held together by ionic bonds in a lattice structure.
共价compound:共价compound is a chemical bond formed by the sharing of one or more electrons, especially pairs of electrons, between atoms.
Properties of Ionic and Covalent Compounds
物理特性
Ionic Compounds:
All ionic compounds exist as solids at room temperature.
离子化合物具有稳定的晶体结构。因此，它们具有较高的熔点和沸点。正离子和负离子之间的吸引力非常强。
| Ionic Compound | Appearance | Melting Point |
| NaCl – Sodium chloride | White crystalline solid | 801°C |
| KCl – Potassium chloride | White or colourless vitreous crystal | 770°C |
| MGCL2– Magnesium chloride | White or colourless crystalline solid | 1412 °C |
共价Compounds:
共价化合物以三种形式存在；作为固体，液体和气体在室温下。
Their melting and boiling points are relatively low compared to the ionic compounds.
| 共价Compound | Appearance | Melting Point |
| HCl-Hydrogen chloride | 无色气体 | -114.2°C |
| CH4-Methane | 无色气体 | -182°C |
| CCl4– Carbon tetrachloride | A colourless liquid | -23°C |
Conductivity
Ionic Compounds:Solid ionic compounds do not have free electrons; therefore, they do not conduct electricity in solid form. But, when ionic compounds are dissolved in water, they make a solution which conducts electricity. In other words, aqueous solutions of ionic compounds are good electrical conductors.
共价Compounds:Neither pure covalent compounds nor dissolved forms in water do not conduct electricity. Therefore, covalent compounds are poor electrical conductors in all phases.
Solubility
Ionic Compounds:大多数离子化合物都可溶于水，但它们不溶于non-polarsolvents.
共价Compounds:大多数共价化合物可溶于非极性溶剂，而不是在水中。
Hardness
Ionic Compounds:Ionic solids are harder and brittle compounds.
共价Compounds:通常，共价化合物比离子固体柔软。
Image Courtesy: “Covalent bond hydrogen” by Jacek FH – Own work.(CC BY-SA 3.0)viaCommons “IonicBondingRH11” by Rhannosh – Own work.(CC BY-SA 3.0)viaWikimedia Commons
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