Lewis structures show molecular bonding and lone pairs of electrons. Introduced by Gilbert N. Lewis in 1916. Uses chemical symbols and lines to represent bonded atoms. Hydrogen can only form two-electron bonds
Valence measures an atom's combining capacity in chemical compounds. Valence is determined by the number of chemical bonds an atom typically forms. Double bonds count as two, triple as three, quadruple as four. Hydrogen typically has valence 1, oxygen 2, nitrogen 3, carbon 4
Double bonds involve four electrons between atoms, unlike single bonds' two. Most commonly found between carbon atoms in alkenes. Can exist between different elements like carbonyl groups. Alexander Butlerov introduced double bonds in chemical notation
CCl4 is a tetrahedral compound with a central carbon surrounded by 4 chlorine atoms. Carbon has 4 lone electrons, chlorine has 7 electrons. Carbon shares its 4 outer electrons with chlorine atoms
Electronegativity measures an atom's ability to attract electrons in bonds. Higher electronegativity means stronger electron attraction. Electronegativity increases from top right to bottom left in periodic table
Carbon and chlorine form a covalent compound by sharing electrons. Total valence electrons are 32 (4 from carbon, 4 from each chlorine). Carbon is placed as the central atom due to its low electronegativity