Chemical bonding project

1. Chemical bonding By: Karla Gonzalez 4 th

2. W hat is a chemical bond? The force the holds two atoms together They may form by the attraction between a positive nucleus and negative electrons or the attraction between a positive ion and a negative ion Types of bonds: ionic, covalent, and metallic

3. Ionic bonds Ionic bonds form when two oppositely charged ions attract They’re composed of one cation (metal) and one anion (nonmetal) High melting and boiling points Good insulators (solids) Hard and brittle When dissolved in water to form and aqueous solution they conduct electricity

4. Ionic bonds: energy the energy produced from ionic compounds is always exothermic The energy required to separate one mole of ions is referred as the lattice energy The more negative the lattice energy the stronger the force of attraction

5. a covalent bond forms when two atoms share electrons They generally occur between elements that are close to each other Majority form between nonmetallic elements A molecule is formed when two or more atoms bond covalently Covalent bonds

6. Single, double, and triple covalent bonds Single bonds : is when a single pair of electrons is shared Single bond Double bonds : occurs when two pairs of electrons are shared to obtain a noble gas configuration Double bond Triple Bonds : is formed when three pairs of electrons are share between two atoms Triple bond

7. Sigma vs. pi bonds sigma Is when the electron pair is shared in an area centered by the two atoms The atomic orbital of both atoms overlap end to end pi Is formed when parallel orbitals overlap to share electrons Always accompanies a sigma bond when forming double and triple bonds

8. Covalent bonds: energy As the number of shared electron pairs increases, bond length decreases The shorter the bond length, the stronger the bond Strength of covalent bonds The amount of energy required to break a covalent bond is called bond dissociation energy The bond dissociation energy is always a positive value Indicates the strength of the bond Has a direct relationship to the bond energy The shorter the bond length, the greater the amount of bond energy needed to separate the elements

9. Metallic bonds A metallic bond is the attraction of a metallic cation for delocalized electrons The electrons of both elements mix to form a sea of electrons The electrons are not held by any atoms so they can move easily from one atom to the other They are often referred as delocalized electrons The high boiling and melting points as well as why metals are good conductors is because the electrons can move freely between the atoms

10. alloys is a mixture of elements that have metallic properties The properties of the alloys are different from those of the elements they contain Two types of alloys: substitutional and interstitial E nergy Metallic bonds do not require a lot of energy to break As the number of delocalized electrons increases so do the properties of hardness and strength

11. Resources Dingrado, Laurel, Gregg V. Kathleen, Hainen Nicholas, Wistrom Cheryl. Chemistry matter and change. New York, New York: McGraw-Hill companies, inc., 2002 www.visionlearning.com www.wikipedia.com