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The diversity of the material world is produced by different ways in which atoms can join together.
Chemical bonding involves the outer electrons of each atoms.
Bonding in the elements
Bonding in the elements
KEY TERM
ION: a charged particle; an atom that has lost or gained elecrons
The DIATOMIC MOLECULES (O2 or H2) are made up of individual atoms moving almost independently of each other are the noble gas (Group VIII).
METALLIC ELEMENT are held together by metallic bonding, which results in metallic lattice.
NON METALLIC ELEMENTS are held together by covalent bonding or exist as separate atoms (the noble gas). Covalent bonding results in simple molecules or giant molecular lattices.
Bonding in metals
Bonding in metals
Metals atoms are more easily to lose electrons than gain them. So they become positive ions. In doing so, they achieve a more stable arrangement, usually the one of the nearest noble gas.
Metals atoms are more easily to lose electrons than gain them. So they become positive ions. In doing so, they achieve a more stable arrangement, usually the one of the nearest noble gas.
The positive ions are packed together, surrounded by a "sea" of free electrons that form a kind of electrostatic "glue".
All metals conduct electricity thanks to the movement of electrons through the structure, carrying electricity.
Bonding in non-metals
Bonding in non-metals
FEATURE OF COVALENT BONDING:
The bond is formed by the sharing of a pair of electrons between two atoms.
Each atom contribuites one electron to each bond.
Molecules are formed from atoms linked together by covalent bonds.
Many non-metals form diatonic molecules as hydrogen molecules, which consist of two atoms bonded together by sharing their electrons.
Others instead, form bonds in order to gain a share of 8 electrons in their outer shell, as you can see in the image (H2O).
N.B.: oxygen and nitrogen are formed when more electrons have to be used in bonding if the atoms are to gain a share of 8 electrons.
O2 are held together by a double bond
N2 are held together by a triple bond
Chemical bonding in compounds
Chemical bonding in compounds
Non-metals + metals (called GIANT IONIC STRUCTURE )are held together by IONIC BONDING, where electrons are transferred from an atom to another producing oppositely charged particles known as ions.
Non-metal + non-metal compounds are held together by COVALENT BONDING, which results in SIMPLE MOLECULES which make up the compounds
-In some elements and compounds (C and SiO2) covalent bonding can result in the formation of GIANT COVALENT LATTICES.
Metal + non-metal compounds are held together by IONIC BONDING between negative and positive ions.
-In ionic bonding the ions are held together by ELECTROSTATIC FORCES of attraction, forming GIANT IONIC LATTICE.
Covalent compounds
Covalent compounds
As in elements also in compounds exist multiple covalent bonds. For example, CO2 is held together by a double bond. Moreover, is the electron arrangement by which depends the acid and the base properties.
Ionic compounds
Ionic compounds
Carbon Dioxide (CO2)
Ammonia (NH3)
Hydrogen chloride (HCl)
Water (H2O)
COMMON FEATURES:
The number of positive charges on a metal ion is equal to the number of electrons lost.
The number of negative charges of a non-metal ion is equal to the number of electrons gained.
In both cases the ions formed have a more stable electron arrangement, usually that of the noble gas nearest to the element concerned.
ionic (electrovalent) bonds result from the attrition between oppositely charged ions.
Ionic compounds are stronger than covalent compounds.
The electrons involved in the formation of ions are those in the outer shell of the atoms.
Metal atoms lose their outer electrons to become positive ions. In doing so they achieve the more stable electron arrangement of the nearest noble gas.
Generally, atoms of non-metals (except hydrogen) gain electrons to become negative ions. Again, in doing so, they achieve the more stable electron arrangement of the nearest noble gas.
Ionic group
Ionic group
Ionic groups are made up of atoms covalently bonded together. All of these groups, a part of ammonium ion that is positively charged, are negatively charged because they have gained electrons to make a stable structure.
ADDITIONAL SOURCE
ADDITIONAL SOURCE
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