1. High School Physical Science Week 8 Ionic and Covalent Bonding

2. Vocabulary Chemical bond, ion, ionic bond, crystal lattice

3. Bonding Chemical bonding is the joining of atoms to form new substances. A chemical bond is an interaction that holds two atoms together. A valence electron is an electron in the outermost energy level of an atom. Most atoms form bonds by gaining, losing, or sharing electrons until they have 8 valence electrons. Atoms of some elements need only 2 electrons to fill their outermost level.

4. Ionic Bonds An ionic bond is a bond that forms when electrons are transferred from one atom to another. During ionic bonding, the atoms become oppositely charged ions. Ionic bonding usually occurs between atoms of metals and atoms of nonmetals. Energy is needed to remove electrons from metal atoms. Energy is released when most nonmetal atoms gain electrons.

5. Ionic Compounds Ionic compounds have ionic bonds between ions of opposite charges. Ionic compounds are usually brittle, have high melting points, dissolve in water, and often conduct an electric current.

6. Naming Ionic Compounds 1.Start with the name of the first atom in the molecule. 2.Take the next atom in the molecule and replace its ending with an “ide” suffix. 3.Putting those two names together gives you the compound’s name. That is why NaCl is called Sodium chloride. It gets more complicated but for now stick with the rules.

7. Covalent Bonding In covalent bonding, two atoms share electrons. A covalent bond forms when atoms share one or more pairs of electrons. Covalently bonded atoms form a particle called a molecule. A molecule is the smallest particle of a compound that has the chemical properties of the compound.

8. Covalent Compounds Covalent compounds have covalent bonds and consist of particles called molecules. Covalent compounds have low melting points, don’t dissolve easily in water, and do not conduct electric current.

9. Naming Covalent Compounds You will be expected to have the following memorized because you will need to know the prefixes for naming covalent compounds. PrefixMeaningPrefixMeaning monoonehexasix ditwoheptaseven trithreeoctaeight tetrafournonanine pentafivedecaten

10. These prefixes are inserted before each name in the compound to indicate how many of each type of atom are the molecule. However if the prefix used on the first atom is “mono”, we drop it.

11. Example of naming a covalent compound CO 2 has the name carbon dioxide. Since there is only one carbon in the molecule we should use the name mono before carbon. But we drop mono and just say carbon. However we have to put a “di” prefix in front of oxygen because we have 2 oxygen atoms present. Just like naming the ionic compounds, we change the last atom’s name to an “ide” ending.

12. Metallic Bonding In metallic bonding, the valence electrons move throughout the metal. A bond formed by the attraction between positive metal ions and the electrons in the metal is a metallic bond. Properties of metals include conductivity, ductility, and malleability.