* Chemical Bonds: When elements combine, they form chemical bonds. This involves the sharing or transfer of electrons, which dramatically alters the way atoms interact with each other.
* New Arrangement of Atoms: The atoms in a compound are arranged in a specific, fixed ratio. This arrangement, along with the chemical bonds, determines the compound's properties.
* Emergent Properties: The properties of a compound emerge from the interactions of its constituent atoms. These properties are often not predictable from the properties of the individual elements alone.
Examples:
* Sodium (Na) and Chlorine (Cl):
* Sodium is a soft, silvery metal that reacts violently with water.
* Chlorine is a poisonous, yellowish-green gas.
* When they combine, they form sodium chloride (NaCl), which is table salt. Salt is a white, crystalline solid that is essential for human life and has very different properties from its constituent elements.
* Hydrogen (H) and Oxygen (O):
* Hydrogen is a highly flammable gas.
* Oxygen is a colorless gas that is essential for respiration.
* When they combine, they form water (H₂O), a liquid that is essential for life and has very different properties from its constituent elements.
Key Point: Chemical compounds are not simply mixtures of elements. They are entirely new substances with their own unique properties.
