Bonding, Formulas, & Reactions

Bonding of Atoms Atoms can attach to other atoms by forming chemical bonds Bonds are created by gaining, losing, or sharing electrons 2 kinds of chemical bonds: Ionic Bonds Covalent Bonds Atoms bond to try to have a full outer shell of electrons

Ionic Bonds Atoms that lose or gain electrons become electrically charged…these are called ions EX. Sodium only has 1 electron in its outer shell, so it will lose that electron to become stable— but charged

Ionic Bonds When oppositely charged ions attract, they form a chemical bond called an ionic bond EX. Sodium and Chlorine

Covalent Bonds Atoms may also bond by sharing electrons rather than by exchanging them The chemical bond between atoms that share electrons is called a covalent bond EX. Water

Molecules & Compounds When 2 or more atoms bond, they form a particle called a molecule When atoms of different elements bond, they form molecules called compounds ALL COMPOUNDS ARE MOLECULES BUT NOT ALL MOLECULES ARE COMPOUNDS!

Formula A molecular formula represents the numbers and types of atoms in a molecule Ex. H2O Count the number of atoms in CH3 C = 1 H = 3 Total = 4 atoms

Chemical Reactions Chemical reactions form or break bonds between atoms, ions, or molecules, generating new chemical combinations There are 4 kinds of reactions: Synthesis Decomposition Exchange Reaction Reversible Reaction

Synthesis Reactions When two or more atoms (reactants) bond to form a more complex structure (product), the reaction is called synthesis Something is being made! A + B  AB

Decomposition Reactions If the bonds within a reactant molecule break so that simpler molecules, atoms, or ions form, the reaction is called decomposition AB  A + B

Exchange Reaction In exchange reactions, parts of two different molecules trade positions as bonds are broken and new bonds are formed AB + CD  AD + CB

Reversible Reaction Reversible reactions are reactions in which the product of the reaction can change back to the reactant.