Chemical bonding

• Ion - atom or group of atoms that has an electrical charge.
• When electrons is transferred or shared between atoms, elements bond together molecularly.
• CHEMICAL SYMBOL -is a notation of one or two letters representing an element.
• CHEMICAL FORMULA - set of chemical symbols showing the elements present in a compound or a molecule and their relative proportions. ex . NaCl- Sodium Chloride
• Subscript- it is to indicate the number of atoms of an element in a compound.
• Coefficient –the number before the chemical formula. It is to indicate that there are more than molecule or ion.
• An atom is basically neutral (equal number of protons and electrons) but during the process of chemical bonding, atoms lose or gain electrons making that atom an ion
• Cation - are positive ions and are usually metal elements. It is a result of losing electrons.
• Anion -are negative ion and are usually non metal elements. It is a result of gaining electrons.
• Polyatomic ions Are groups of atoms (two or more covalently bonded atoms) which carry electrical charges as unit particles.
• Gilbert Newton Lewis ◦ Proposed that chemical bonds are formed between atoms because electrons interact with each other.
• elements are most stable when they have 8 electrons in their valence shell. This rule is known as octet rule.
• Octet rule - a chemical rule that reflects observation that atoms of main groups (family A) elements tend to bond in such a way that 8 electrons is present in its valence shell.
• Lewis Dot Symbol - consist of chemical symbol and dot around which dot is equal to its number of valence electrons.
• Chemical Bond - is an electrical attraction between the nuclei and valence electrons of an atom and which atoms binds atom together.
• Intramolecular force (inside) - is a force that binds together the atoms making up a molecule or a compound.
• Intermolecular forces (outside) - is a force that binds one molecule to another.
• Ionic Bonding- results from the transfer of one or more valence electrons from one atom to another.
• Formula unit- a pair cation and anion form during ionic bonding.
• Ionic Compound

  • Usually between metal and non-metal elements.
  • Dissolve easily in water and polar solvents.
  • Easily conduct electricity
  • Usually solid and tend to crystallize
  • Has high melting point.
• Covalent bond- when atoms share electrons forming a bond between atoms. ◦ It occurs between two non-metal elements. It occurs because 2 non-metal elements have similar tendency to gain electrons.
• Molecular compounds- the compounds that consist of atoms bonded together by sharing electrons.
• To represent chemical bonding Lewis Electron Dot Structure (LEDS) is used.
• Electronegativity - is a measure of the tendency of an atom to attract electrons towards itself.
• If it is based on electronegativity. Put the least electronegative element at the center and the most electronegative as the outside atom.