Chapter 6 Section 1 Notes

Electron Configuration A. Stable Electron Configuration a. When the highest occupied energy level of an atom is filled with electrons, the atom is stable and not likely to react. b. The noble gases have stable electron configurations with eight valence electrons. c. The chemical properties of an element depend on the number of valence electrons.

Electron Configuration d. A model of an atom that focuses on only the valence electrons is the electron dot diagram. e. An electron dot diagram is a model of an atom in which each dot represents a valence electron. The symbol in the center represents the nucleus. f. Orbital diagrams and Electron Configurations both show how the electrons fill the various orbitals in each energy level. (Refer to the Electron Configuration activity)

Electron Dot Diagram 1A2A3A4A5A6A7A8A HHe LiBeBCNOFNe NaMgAlSiPSClAr KCaGaGeAsSeBrKr

Ionic Bonding B. Ionic Bonding a. Elements that do not have a complete set of valence electrons tend to react. b. The goal of an element reacting is to achieve an electron configuration similar to that of a noble gas. c. Some elements achieve stable electron configurations through the transfer of electrons between atoms. Ex. 1) What happens to the electrons when sodium reacts with chlorine? An electron is transferred from each sodium atom to a chlorine atom. Each atom ends up with a more stable electron arrangement than it had before.

Ionic Bonding d. When an atom gains or loses an electron, the number of protons is no longer equal to the number of electrons. Therefore the charge of the atom is no longer neutral. e. An ion is an atom that has a net positive or negative electric charge. It is represented by a + or – sign. (Refer to example 1) f. An anion is an ion with a negative charge.

Ionic Bonding g. A cation is an ion with a positive charge. h. A chemical bond is the force that holds atoms or ions together. i. An ionic bond is the force that holds cations and anions together. 1. An ionic bond forms when electrons are transferred from one atom to another.

Ionization Energy C. Ionization Energy a. The amount of energy used to remove an electron from an atom. b. The lower the ionization energy, the easier it is to remove an electron from an atom. c. This energy decreases going down the periodic table and increases going across the periodic table from left to right.

Ionic Compounds D. Ionic Compounds a. Compounds that contain ionic bonds. b. A chemical formula is a notation that shows what elements a compound contains and the ratio of atoms or ions of these elements in the compound.

Ex. 1) Sodium Chloride

Ex. 2) Magnesium Chloride