Compounds
Compound
- a substance formed when two or more elements combine chemically in fixed ratios.
- The compound has different properties than the elements that combine to form it
Chemical Bonding
- the combining of atoms of elements to form new substances
- occurs according to certain rules determined by the structure of the atom
The electron arrangement of the outer energy level
of an atom determines whether or not it will form bonds
When the outer energy level is full (usually 8 electrons in outer energy level)
the atom is inert (stable or unreactive) ( I like to think of it as "happy :)" )
- To obtain stability ("get happy :)"), elements will do one of the following
- gain electrons
- lose electrons
- share electrons
Types of bonds
- Ionic Bonds
- formed by transfer of electrons
- one atom loses electrons, another atom gains electrons
- charged particles Ions are formed
- the atom losing electrons is now a positive ion
- the atom gaining electrons is now a negative ion
- the oppositely charged particles are then attracted to each other
- this attraction gives them great stability
- because of this, ionic compounds have high melting points
- occurs when a metal and a nonmetal react to from a compound
- Covalent Bonds
- bonding in which electrons are shared
- by sharing electrons each atom fills up its outer energy level
- both nuclei are attracted to the electrons that are being shared
- covalent bonding results in the formation of a molecule
- most covalent compounds have low melting points
- covalent bonding generally occurs between two nonmetals
- Metallic Bonds
- Bonding that occurs between atoms of metals
- the positive nuclei of atoms are surrounded by mobile electrons
that are all attracted by the nuclei at the same time
- the electron sea accounts for the properties of metals:
- malleability (can be flattened into sheets)
- ductility (can be drawn into thin wires)
- high melting point
- conductivity (conducts heat and electricity)
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