Chapter 6 The Structure of Matter Chemical Bonds

Chapter 6 The Structure of Matter

Chemical Bonds Forces that hold atoms together in a compound Remember: a compound is made up of 2 or more elements Chemical bonds can be broken & rearranged under certain conditions

Chemical Structure Arrangement of atoms in a substance Chemical bonds can bend, stretch, & rotate without breaking The structure determines the chemical properties of a compound

Chemical Bonds Atoms join to form bonds so each atom gets to a stable e- configuration Ionic Bonds Attraction between oppositely charged ions Formed between metals & nonmetals Formed by the transfer of electrons Na gives away an e- (becomes pos. ) & Cl takes the extra e(becomes neg. ) The new positive & negative ions attract each other

Chemical Bonds Covalent Bonds Atoms joined by covalent bonds share electrons Formed between nonmetal atoms Covalent compounds can be solid, liquid, gas Atoms may share more than 1 pair of e 1 pair = single bond 2 pair = double bond 3 pair = triple bond

Chemical Bonds Metallic Bonds between metal atoms

HOMEWORK Chemical Bonds WS Pg. 182 # 1 Pg. 190 # 1, 3, 5

Chemical Reactions Occur when substances go through chemical changes to form new substances Rearrange atoms Isoctane (C 8 H 18) and oxygen (O 2) react to form carbon dioxide (CO 2), water (H 2 O), & energy Reactant: Substance or molecule that participates in a chemical reaction C 8 H 18 & O 2 Product: Substance that forms in a chemical reaction CO 2 , H 2 O, & energy

Chemical Equations Uses symbols to represent a chemical reaction Shows relationship between reactants & products C 8 H 18 + O 2 -> CO 2 + H 2 O + energy

Chemical Reactions Energy must be added to break chemical bonds Endothermic Reaction: rxn that absorbs energy If in a beaker, beaker gets colder Forming new bonds releases energy Exothermic Reaction: rxn that releases energy If in a beaker, beaker gets warmer

Chemical Reactions Energy is always conserved during a chemical reaction Energy is never created nor destroyed Law of Conservation of Energy Chemical Energy released when a chemical compound reacts to produce new compounds

HOMEWORK Chemical Reactions WS Pg. 224 # 1 -3, 5