3.3 Interactions of Matter Bonding
Chemical Compounds Add to your notes! • Formed by the interactions of individual atoms. • Electrons found in the outermost energy level dictate what kind of bonding will occur. • A chemical compound is a group of atoms held together by chemical bonds. • Compounds are represented by chemical formulas. • Examples of chemical formulas: • NaCl – table salt • H2O – water • NH3 – ammonia • C6H12O6 - glucose
Counting Atoms If there are no numbers, there is only one atom of each element present. Ex: LiBr Li: 1 Br: 1 If there is a number and only one element, there are that many atoms of that element. Ex: O2O: 2 If there are multiple elements and a number, there are that many atoms of the element the number is beside. There are only 1 of each of the other elements. Ex: CaSO4Ca: 1 S: 1 O: 4 If there are parenthesis, the number corresponds to all elements inside the parenthesis. Ex: Si(OH)4Si:1 O: 4 H: 4 If there are parenthesis with a number inside of the parenthesis, distribute (by multiplying) the number outside the parenthesis to the elements inside the parenthesis. Ex: Ca(NO3)2 Ca: 1 N: 2 O: 6
Atoms have Energy Remember this? • Each energy level can hold a certain number of electrons. • First level: 2 electrons • Second level: 8 electrons • Third level: 8 electrons • Fourth level: 10 electrons
Why do Atoms bond? • When the outermost energy level of an atom contains the maximum number of electrons, the level is full, or complete. • In order to achieve stability, an atom will either gain, lose or share electrons. (an atom will bond with another atom if the bonding gives both atoms complete outermost energy levels.
Ionic Bonds • Transfer of electrons from one atom to another • Ions are formed when an ionic bond occurs.
Covalent Bonds • chemical bond formed by the sharing of electrons • The shared electrons are in the outermost energy level of both atoms at the same time. • produces a strong bond- most chemicals found in living organsims are held together by covalent bonds • Can be single, double, or triple • Depends on the number of electrons shared in the bond