Presentation on theme: "Chemical Bonds The strong attraction between atoms or ions."— Presentation transcript:
Chemical Bonds The strong attraction between atoms or ions
Types of Chemical Bonds We will study 4 types of chemical bonds: Ionic Bonds Bonds between metals and non-metals Electrons are transferred Covalent Bonds Bonds between two non-metals Electrons are shared Metallic Bonds Bonds between two metals Intermolecular Bonds Bonds between molecules
Chemical Reactivity Some chemicals are reactive and some are not Name the most reactive metal on the periodic table:____________________ Name the most reactive non-metal on the periodic table:____________________ Name the non-reactive gases on the periodic table:___________________________
Chemical Reactivity Why are the noble gases not reactive? ____________________________________ ____________________________________ Draw the Bohr model of the outer valence shell of Neon:
Chemical Reactivity If the noble gases are not reactive due to their outer shell configuration, then the alkali metals and halogens must be very reactive because: ______________________________________
Chemical Reactivity Draw the Bohr model outer shell valence configurations for sodium and fluorine: SodiumFluorine If sodium loses its one valence electron, will it have a full outer energy level? _______ If fluorine gains one valence electron, will it have a full outer valence energy level? ________
Chemical Reactivity Does having a full outer valence electron configuration make an atom more stable? Why? OCTET RULE: atoms will form bonds to achieve a stable, noble gas electron configuration (usually 8 electrons, however, remember that helium has only 2 valence electrons)
Chemical Reactivity Why doesn’t sodium try to gain seven more electrons rather than giving one away? ______________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ Why can fluorine gain electrons?
Chemical Reactivity Please note: Hydrogen can gain or lose an electron Helium is stable because its valence shell is full with only two electrons (it only has 2 protons). Lithium (three protons) and Beryllium (4 protons) will also be stable with only two electrons in their valence shell.
General Information About Bonds Chemical bonds have stored (potential) energy Energy must be absorbed to break a chemical bond Energy is released during bond formation
Ionic Bonds When a metal atom transfers electrons to a non-metal atom, an IONIC BOND is formed The two atoms are attracted by their opposite charges http://www.teachersdomain.org/asset/lsps07_int_chembonds/
Ionic Bonds Do the two atoms in the previous slide have fuller outer octets? Does this make sodium chloride stable or unstable?
Bond Character An ionic bond occurs when the electronegativity difference between its atoms is 2.0 or greater. Example: Electronegativity of Sodium:___________ Electronegativity of Chlorine:___________ Difference in Electronegativity___________ Based on the above information, is this an ionic bond?_______________
Ionic Bond Summary 1. Formed by the ___________________of electrons. 2. Form when a ___________________ion and _____________________ion attract each other. 3. Have an electronegativity difference of _________or more.
Ionic Salts Atoms in an ionic compound tend to arrange themselves in specific orderly patterns (crystalline structures) and form salts
Ionic Salts Salts are Hard and Brittle Crystals are arranged in repeating patterns, which form layers Each cation is positioned next to an anion The attractive force between these oppositely charged ions make it very strong It takes a lot of energy to break these bonds
Properties of Ionic Substances (salts) MEMORIZE THE FOLLOWING!!! 1. All are solid at room temperature. 2. Are hard and brittle; should not break easily. If it does break, it is into smaller crystals. 3. Have high melting and boiling points. 4. Ionic compounds that are melted will conduct electricity. 5. Ionic compounds dissolved in water will conduct electricity. 6. Will dissolve in polar compounds.